FAQ Sökare

Select the determinations of this standard in the "Database" as well as all determinations of samples that are to be recalculated. In the "Determinations" menu, select "Reprocessing…" or click the corresponding icon. Select the affected standard in the "Reprocessing table" and open the reprocessing of sample data by double-clicking or via "Edit">"Edit line". Correct the "sample type" and then select "Apply" and "Close". Select "Reprocessing" and then the option "From the standards of the reprocessing table". All the determinations are recalculated using the parameters of the selected line. If the result of the reprocessing is satisfactory, save the reprocessed determinations by closing the reprocessing window with "OK". The procedure for further problems during "Reprocessing" is described in the online help under "How to proceed?".

As a temporary solution, you can replace the bridge electrolyte with a water-free electrolyte, e.g., c(LiCl) = 2 mol/L in ethanol.

We recommend a completely water-free reference electrode for permanent application. Both the reference system and the electrolyte vessel are filled with a water-free electrolyte. For this purpose, the internal reference system is also available dry with no electrolyte. The order number for this is 6.0728.010. The bridge electrolyte vessel 6.1245.010 is compatible with this.

c(tetrabutylammonium chloride) = 0.1 mol/L in acetonitrile, for example, is a suitable reference electrolyte. The electrolyte used for the application can be used as the bridge electrolyte. You must bear in mind that the electrode has a different reference potential with this reference electrolyte than with c(KCl) = 3 mol/L.

Caution! Reference systems with an LL Ag/AgCl system (6.0728.x30) are not suitable for use with acetonitrile.

The following error message appears: «Printing error (017-117); an error has occurred during printing. Check the printer, the determination, or the report template». So far, this has always been because the paper tray in the printer was empty.

Here you will find the ordering information for the individual parts of your Multi-Mode Electrode pro (MME pro).

Here you will find the ordering information for the individual parts of your Multi-Mode Electrode (MME).

At room temperature (approx. 20 °C) and normal pressure (approx. 1000 hPa), mercury metal is liquid. The toxicity depends on the chemical and physical state of the mercury. Metallic liquid mercury is used in polarography/voltammetry.

Metallic liquid mercury

Metallic liquid mercury is relatively harmless. «If mercury is swallowed most of it passes through your body and very little is absorbed. If you touch mercury for a short period of time a small amount may pass through your skin, but not enough to harm you.» [1]. However, the problem is that metallic mercury evaporates at room temperature at a rate of 0.056 mg/(h·cm2) [2]. By comparison, the evaporation rate for water is 10 mg/(h·cm2) at room temperature [3]. Mercury vapors are absorbed through the lungs very easily and can cause both acute and chronic poisoning. For this reason, mercury should never be stored in the open and, if any drops are spilled, they must be collected immediately.

Mercury(I) salts

The sparingly soluble, inorganic mercury(I) compounds have low toxicity when taken up orally (but not through the skin!).

Mercury(II) salts

Mercury(II) compounds are more readily soluble and therefore much more toxic. Toxicity to fish: LC50 – Oncorhynchus mykiss (rainbow trout) – 0.016 mg/L – 96 h [4].

Mercury vapors

Mercury vapor, which is already formed at room temperature, is highly toxic: vapor with a mercury concentration exceeding the TLV (threshold limit value) or OEL (occupational exposure limit value) causes chronic poisoning after prolonged breathing for 5 to 8 hours per day. The limit values vary depending on the country and range between 20 and 100 µg/m3 of air [5][6][7][8]. Despite the large number of laboratories involved in polarographic/voltammetric work, sensible and proper handling has ensured that not one single case of mercury poisoning has been reported to date. The real Hg concentrations measured in the laboratory atmosphere are consistently far below the TLV.

Organic mercury compounds

Organic mercury compounds are very toxic. Dimethylmercury is an extremely toxic form of organic mercury, and very small exposures can cause severe and irreversible delayed neurotoxicity, including death. Dimethylmercury is thought to be metabolized to methylmercury prior to crossing the blood-brain barrier. Dimethylmercury is quickly absorbed through intact skin, and it will penetrate latex or polyvinyl gloves. It is highly volatile, will readily evaporate, and can be inhaled [9].

 

[1] Mercury Quick Facts – Health Effects of Mercury Exposure, Agency for Toxic Substances and Disease Registry, www.atsdr.cdc.gov/mercury/docs/healtheffectsmercury.pdf

[2] United Nations Environment Programme (UNEP), Code of Practice Mercury Housekeeping, https://www.unep.org/resources/report/code-practice-mercury-housekeeping

[3] F. Asdrubali, A scale model to evaluate water evaporation from indoor swimming pools, Energy and Buildings, 41 (2009), 311–319

[4] Material safety data sheet for mercury(II) chloride, https://www.merckmillipore.com/CH/de/product/msds/MDA_CHEM-104419

[5] Occupational Safety and Health Administration standards related to mercury, https://www.osha.gov/mercury/standards

[6] Technische Regeln für Gefahrstoffe 900 – Arbeitsplatzgrenzwerte http://www.baua.de/de/Themen-von-A-Z/Gefahrstoffe/TRGS/TRGS-900.html

[7] Bundesamt für Gesundheit – Quecksilber – Factsheet Quecksilber, https://www.bag.admin.ch/dam/bag/de/dokumente/chem/themen-a-z/factsheet-quecksilber.pdf.download.pdf/factsheet-quecksilber_de.pdf

[8] European Commission, Brussels, BiPRO 16 April 2010, Requirements for facilities and acceptance criteria for the disposal of metallic mercury, http://ec.europa.eu/environment/chemicals/mercury/pdf/bipro_study20100416.pdf

[9] John Risher, Ph.D., Rob DeWoskin, Ph.D. 1999, Agency for toxic substances & disease registry. Toxicological Profile for Mercury. 1999. http://www.atsdr.cdc.gov/toxprofiles/tp46.pdf

The induction time measured using the Rancimat cannot be used to directly calculate shelf life.

An important reason for this is that the experiments are structured differently. Measurements using the Rancimat are generally made at temperatures between 100 °C and 130 °C. In addition to accelerating the oxidation process, these temperatures can cause side reactions which do not occur when samples are stored under normal conditions. For example, volatile antioxidants may be driven out or antioxidant compounds may form (e.g., Maillard reaction). Furthermore, in measurements with the Rancimat, air is continuously fed through the sample, whereas it is generally stored in closed containers.

Consequently, the induction time determined using the Rancimat only gives an indication which must be correlated with the actual shelf life of a sample using storage tests.

Determinations are not stored as individual files, but in a database. They can, however, be exported from the database and stored as *.idet files. The *.idet files can be imported into other MagIC Net databases. The version of the receiving MagIC Net must be the same or higher.

The exact volume of the measuring solution is less significant when determining the induction time, as only the relative change in conductivity is evaluated.

The working electrode needs to be cleaned. Carry out a conditioning procedure in pure VMS. If applicable, the electrode needs to be cleaned.

A "batch" is a collection of different "Determinations" within a database.

The assignment of determinations to a "batch" can be carried out when entering the sample data at the workplace. An existing or a new batch name can be chosen. In the first case, the determinations are added to the selected "batch", and in the second case, a new "batch" is created. In the database, it is also possible to create or delete a "batch" or to add existing determinations to a "batch".

These determinations can be simply filtered out of the whole set of determinations using the batch names. The batch assignment is used for fast viewing of data that belong together. There are also further options, such as filters, etc., to find data.

The maximum batch size is 500 determinations. If an attempt is made to add more determinations, these will be ignored. New determinations are normally stored in the "Database". No data is lost.

If a "Batch" is deleted, only the links of the determinations to the "Batch" are deleted, but no data.

In the event of network interruptions, client enquiries to the database (Determination Start, Report, Database, and Export commands) are held until the database is accessible again (without time limit). Device processes are not affected − they continue to run.

After recalculation the result disappears from the view. This is not a bug, but can occur if the database view has been filtered. After recalculation the view is updated, thus a result can «disappear». In this case, the filter must be reset or changed.

The example methods are saved as *.imet files during installation in a subdirectory of the program directory.

If such an example method is to be used, it must be imported using "Method manager" into a "Method group". If this method is to be used directly with the existing IC system, the same devices and module names must be used. If "Common variables" are used in the method, they must be created first under "Configuration".

Devices, intelligent modules, and components are automatically detected by MagIC Net and registered under "Configuration". As soon as a new component is detected, a window appears in which the individual details can be adjusted.

Non-intelligent components and accessories can be registered manually in the appropriate category. This allows monitoring of all parts in the IC system that must be maintained or replaced at regular intervals.

During measurement, sample components may be absorbed by the plastic. This occurs in particular when measuring biodiesel and can cause the cover to expand. An important measure for counteracting this is to heat the cover after cleaning (see Cleaning after the determination). If heating the cover still does not enable a seal to be formed with the reaction vessel when it is closed, the cover must be replaced.

The database remains the same size as before. The freed-up space is now occupied by new data records, so the size of the database does not increase until the freed-up space has been filled again.

The "Time program" in the "Method" consists of at least one "Main program". This defines the chronological sequence of the analysis run (sampler commands, injection, start of data acquisition, etc.). Subprograms can be inserted to prevent the "Time program" becoming too complex or to allow functions that are independent of the sample.

The subprograms can be linked to "Conditions" that are used to decide whether they are to be started or skipped. For example, a subprogram can be created that is only executed for determinations used for calibrating the method.

The Metrohm CO2 Suppressor (MCS) requires CO2-free air. This means that the aspirated ambient air has to be precleaned using a CO2 adsorption cartridge. The CO2 adsorption cartridge must be replaced when approx. three quarters of the material has turned a violet color or at least once per year.

CVS measurements are temperature-dependent. Strong temperature fluctuations (+/- 4 °C) should be avoided to get reliable analysis results.

The CVS measuring instrument used should not be near the air outlet.

During the measurement, the temperature of the measuring solution should be kept constant. If a warm or hot bath sample is transferred into the measuring vessel, then the temperature should be adjusted. If necessary, it is possible to work with a measuring vessel with thermostat jacket (see image) and an external thermostat/cryostat. For more information, download our technical poster.

8.000.6027        Temperature dependence of CVS determinations (technical poster)

The client ID can be changed via Setup Routine and [Modify].

Metrohm does not recommend any mechanical treatment of platinum RDEs, e.g., by polishing with aluminum oxide!

The gas flow does not have a significant effect on the end result as long as it is ensured that the sample can be mixed well and the cooling effect is compensated for by correctly determining the temperature correction.

Technical poster

8.000.6081 (Determination of the oxidative stability of biodiesel (fatty acid methyl esters, FAME))

Only the visible databases are represented for selection in the window. As you can choose your own settings for the visibility of each database under the access rights for the databases, tiamo must first open all databases. With a lot of databases this takes longer, though the time is greatly dependent on server performance.

No, harmful indicators are not used.

The background conductivity is defined by the eluents and the suppression reaction. This means that the eluent composition may be incorrect or suppression is incomplete. If suppression is used, make sure that the suppressors (MSM and MCS, if present) are connected correctly. Check the flow of the regeneration solution and the rinsing solution.

The tubes of a peristaltic pump are a consumable with a limited service life and should be replaced at regular intervals (approximately every 2 months if used continuously).

There are two different positions for attaching the tube. The position should be changed once a month.
The pressure of the tubing cartridge must not be too high: Increase the pressure incrementally until you can see that the liquid is flowing. Then increase the pressure with the contact pressure lever by a further two increments.

Use 3-stopper pump tubings with a longer service life: 6.1826.3X0 and 6.1826.4X0.

Inline Filters must be used for regeneration and rinsing solutions and must be replaced every three months or if the backpressure is too high.

All dosing units used should be rinsed with distilled water in order to prevent a possible crystallization of metal salts.

The contact pressure of the tubing cartridge is set too low: Set the contact pressure of the tubing cartridge in accordance with the sample changer manual.

The pump time of the peristaltic pump is increasing: The pump tubing of the peristaltic pump has aged or is defective and should be replaced.

The PEEK sample needle on the Sample Processor is positioned more than 0.5 mm from the bottom of the sample vial: Position the PEEK sample needle in accordance with the information in the manual.

A. The electrodes are not well conditioned. Please perform a conditioning procedure on the electrodes.

B. The temperature is instable.

Increased baseline noise can be caused by various components:

• The eluent is not sufficiently degassed: Make sure that the connectors of the eluent degasser are tightly connected.

• The eluent path has a leak: Check the connections.

• The high-pressure pump has contaminated valves: Clean or replace the pump valves.

• The high-pressure pump has defective piston seals: Replace the piston seals and, if necessary, the pistons.

• The pulsation absorber is not connected or is defective: Connect or replace the pulsation absorber.

• MCS – The CO2 cartridge is exhausted: Replace the CO2 cartridge.

• MCS – The vacuum pump is faulty: Please contact Metrohm Service.

Prepare the eluents with degassed and CO2-free ultrapure water. Dissolved CO2 can affect the pH and thus also the retention times.

If the drift during pretitration (conditioning) is too high after the addition of fresh working medium, then this is a sign that the titration cell is not protected sufficiently against humidity. Replace the molecular sieve and the septum. Also check to see whether all of the O-rings/PTFE sleeves are in proper condition.

MISP method for automatic sample extraction, e.g., extraction of ions from (bio)diesel.

	Sample size for 5 mL buret
Type of standard	Titrant 1	Titrant 2	Titrant 5
Water standard 10 mg/g	0.05–0.45 g	0.1–0.9 g	0.25–2.25 g
Na tartrate 156.6 mg/g		0.006–0.057 g	0.03–0.27 g
Water 1000 mg/g	–	–	~ 0.02 g
Water	–	–	~ 20 µL

 

	Sample size for 10 mL buret
Type of standard	Titrant 1	Titrant 2	Titrant 5
Water standard 10 mg/g	0.1–0.9 g	0.2–1.8 g	0.5–4.5 g
Na tartrate 156.6 mg/g	0.02–0.057 g	0.013–0.115 g	0.03–0.287 g
Water 1000 mg/g	–	~ 0.015 g	~ 0.025 g
Water	–	~ 15 µL	~ 25 µL

 

	Sample size for 20 mL buret
Type of standard	Titrant 1	Titrant 2	Titrant 5
Water standard 10 mg/g	0.2–1.8 g	0.4–3.6 g	1–9 g
Na tartrate 156.6 mg/g	0.02–0.175 g	0.026–0.23 g	0.065–0.58 g
Water 1000 mg/g	–	0.02–0.035 g	0.02–0.09 g
Water	–	15–35 µL	15–90 µL

Volumetric Karl Fischer Titration cell:

 

Coulometric Karl Fischer Titration cell:

 

Platinum electrode tips with a glass shaft can be operated up to a maximum temperature of 50 °C.

Platinum electrode tips with a PEEK shaft can be operated up to a maximum temperature of 40 °C.

Similar to MiPCT, but with additional Inline Matrix Elimination.

The platinum electrode tip can be immersed for a few seconds in concentrated nitric acid to oxidize a metal coating which has accidentally been applied. If after another measurement foreign metal should be found on the surface again, then the method parameters and electrode connectors need to be checked.

The following manufacturers offer KF reagents:

Honeywell:
www.hydranal-honeywell.com

Sigma-Aldrich:
http://www.sigmaaldrich.com/analytical-chromatography/titration/karl-fischer-titration.html

Basic eluents can absorb CO2 from ambient air, which alters their pH value. This affects the retention times. Adsorption of CO2 can be prevented with a CO2 adsorber.

The solvent keeps flowing into the titration vessel after the addition, without the «addition» key being pressed.
Set the solvent bottle up in such a way that the fluid level in the bottle is lower than in the titration vessel.

Solvent is added simultaneously during aspiration.
The drying tube in the titration vessel is blocked:

• Enlarge the hole on the drying tube cover to at least 2 mm
• Refill the drying tube, do not pack too tightly, possibly remove some of the molecular sieve.

The pump conveys no fluid.
Press the «addition»/«aspiration» key more strongly.

• In most cases the bottle attachments are not screwed tightly enough to the reagent and waste bottles
• Check all connections for leak-tightness
• Check whether the 803 Ti Stand is set up correctly

GLP (Good Laboratory Practice) requires, among other things, periodic checking of the analytical instruments for their reproducibility and correctness on the basis of Standard Operating Procedures (SOPs). It is recommended that the instruments are qualified on a regular basis

For more information please contact us.

It is difficult to make a general statement concerning how often the molecular sieve should be replaced, because this is dependent on the humidity in the laboratory. Our experience has shown us that replacement every six weeks is appropriate in the presence of medium humidity. An increase in drift indicates that the leak-tightness of the cell should be inspected and that the molecular sieve should possibly be replaced.

Tip: Write the date on which you have last replaced the molecular sieve on the glass of the drying tube. In this way, you will always know when the next replacement is due.

A check box ("Stop hardware when sample table has finished") is located at the bottom right of the run window of the sample series.

If this check box is checked, the device is stopped automatically. This setting is stored for each workplace. Different systems running at different workplaces on one computer can thus be set up differently.

The 800 Dosino was not attached correctly:

• Remove the 800 Dosino and attach it again.
• Check whether the 800 Dosino is correctly attached.
• Disconnect the CVS measuring instrument from the power supply and connect it again.
• If necessary, contact Metrohm Service.

The bridge electrolyte forms an electrical bridge between the measuring solution and the reference electrode. In many cases a strongly acidic measuring solution is used in CVS analysis. Over time, the acid may also reach the bridge electrolyte and thereby change the reference potential. This is why changing the bridge electrolyte every day is recommended. The reference electrodes filled with KCl gel are maintenance-free, which means that no electrolyte needs to/may be changed.

Always use only ultrapure water (Grade I, 18.2 MOhm at 25°C) for eluents, dilutions, and all other solutions that will be used for IC.

Eluents must always be prepared with analytical grade chemicals (i.e., with at least purity grade "p.a." or "analytical grade").

Freshly prepared eluents must always be microfiltered (0.45 µm filter) and then degassed with N2, He, or in a vacuum or with an inline degasser. If possible, a CO2 absorber should be used for basic eluents and eluents with a low buffer capacity.

The database comprises a directory with subordinate files and subdirectories. The database directory name is used in tiamo as a database name.

It is recommended that you repeat annually the testing of the instruments used for determining water content according to the Karl Fischer method. If an instrument is in continuous use, then more frequent testing intervals may be called for, e.g., every 6 months or even every 3 months. Unscheduled validations are called for when one or more components of the titration system have been replaced.

MISP method to add a known quantity of ions to a sample during preconcentration.

Typical application: check of recovery rates in a preconcentration system.

One reason for peak broadening is additional dead volume. This can occur if the capillary connections are not optimal and with old separation columns. Check the connections. If the dead volume is in the column head, the separation column can be operated for a certain time in the opposite direction (provided that this is permitted according to the column leaflet), otherwise the separation column must be replaced.

A further reason could be contamination of the guard column and/or the separation column. Replace the guard column. If the separation column is contaminated, regeneration (according to the column leaflet) may help. Otherwise, the separation column must also be replaced.

For volumetric KF titration, a general distinction is made between one-component and two-component reagents:

One-component reagent		Two-component reagent
Working medium	Titrant	Working medium	Titrant
Methanol	Alcohol*/DEGEE** Base SO2 Iodine	Iodine Alcohol*	Alcohol* Base SO2
Advantages: A larger amount of solubility promoters can be added		Advantages: Stable titer, because reactive components are separated Quick reaction thanks to optimum pH value in the working medium
Disadvantages: Titer decreases approximately 5% per year in the closed bottle		Disadvantages: Limited water capacity

* Methanol or ethanol
** Diethylene glycol monoethyl ether

Reagents for coulometric KF titration contain iodide. The suitable reagent needs to be selected in accordance with the type of generator electrode (with or without diaphragm). For more information on the different types of coulometric KF reagents please refer to the manufacturers of KF reagents.

Here you will learn what is to be done if the reference electrode ever dries out.

The 6.0728.x40 reference system cannot be regenerated if it dries out. The electrode must be replaced.

Dried-out KCl gel cannot be removed from the electrolyte vessel. The electrolyte vessel must be replaced.

Once the gel filling of the electrode 6.0730.x00 has dried up, the gel reference electrode is irrevocably damaged and must be replaced!

MISP method for filtration of sample solutions prior to injection.

The sample is fed past the filtration membrane. A pump is used to filter a small fraction of the sample stream through the membrane (partial vacuum) for subsequent analysis. The remainder of the sample stream flows into the waste container and simultaneously rinses the filtration membrane. This minimizes formation of a filter cake and thus a possible blockage of the membrane pores. Inline Dialysis can be used as an alternative if the samples are too heavily contaminated.

Typical applications: all samples that have to be filtered, e.g., natural waters (surface water, groundwater, wastewater, etc.).

Accessories

The following accessories are generally used to determine the thermostability of PVC:

• 6.1429.040 Reaction vessel short (150 mm)
• 6.2418.120 Air tube PVC (140 mm)
• 6.1428.107 Measuring vessel (polystyrene)
• 6.1816.010 Silicone tubing

All the accessories required for more than 100 determinations are included in the scope of delivery of the 895 Professional PVC Thermomat. 

Standard method parameters
Sample amount	0.5 g
Measuring solution (water)	60 mL
Sample temperature	200 °C
Gas flow (air)	7 L/h
Evaluation	Stability time Conductivity change 50 µS/cm

A. It is usually sufficient to clean the platinum pins of the electrode with a soft paper tissue. However, you should take care to ensure while doing so that the platinum pins are not pressed together. They should always be parallel to one another.

B. In volumetric KF titration, the antidiffusion valve on the buret tip should be checked.

See the photo: good buret tip in comparison with defective buret tips

C. Check if you are using the recommended parameters:

Volumetric KF titration

 

	Ethanol-containing reagents	Methanol-containing reagents
Polarization current Ipol	20 µA	50 µA
Endpoint indication at	500 mV	250 mV

Coulometric KF titration

	Ethanol-containing reagents	Methanol-containing reagents
Polarization current Ipol	10 µA	10 µA
Endpoint indication at	20 mV	50 mV

D. A further cause of overtitration could be that the initial solution no longer contains sufficient methanol or ethanol. In such a case it is worthwhile to renew the cell solution and/or to check whether too much solubility promoter has been used. Read for more details in the following FAQ: «How often must the KF working medium be replaced?».

See table: Solubility promoters for volumetric and for coulometric titration

Volumetric KF titration

Solvent	Percentage	Samples
Formamide	max. 50%	Sugar samples, salts
Chloroform	max. 70%	Oil, grease
Long-chain alcohols	max. 50%	Oil, grease
Xylene, toluene	max. 70%	Crude oils with tars

Coulometric KF titration

Solvent	Percentage	Samples
Formamide*	max. 20%	Sugar samples, salts
Chloroform**	max. 30%	Oil, grease
Long-chain alcohols**	max. 30%	Oil, grease
Xylene, toluene**	max. 30%	Crude oils with tars

 
* Only with generator electrode without diaphragm.
** Use generator electrode with diaphragm if the amount of solubility promoter is higher than 10%.

Additional measures:

E. Increasing the stirring rate.
F. Check whether the platinum pins of the electrode are immersed completely in the cell solution.
G. Check whether the correct reagents were combined: if the titrant of the two-component reagent is used with methanol, the KF reaction cannot take place, because no SO2 is available for the reaction. (Only volumetric KF titration.)

Results may be too high for the following reasons:

Cause	Remedy
Side reaction	Read for more details in the following FAQ: «How to recognize a side reaction? How to prevent side reactions?»
The sample is hygroscopic	Here we recommend optimizing the sampling and the sample storage as well as working speedily during the determination.
The sample is inhomogeneous	Increase the sample size. Homogenize the sample prior to the determination.
Overtitration	Read for more details in the following FAQ: «Overtitration took place, i.e., the titrated solution is dark yellow to brown instead of light yellow. How to prevent this?»
Only for volumetric KF titration:
The titer has changed since the last determination	Redetermine the titer.
Air bubbles in the tubing	Flush the tubing system using the Preparation/«Prep» command.
Non-leak-tight tubing system	Check for crystals in the tubing system. Check whether tubing is connected tightly. Check tubing connections.

The dosing units used should be disassembled and thoroughly cleaned at 14-day intervals.

A different reference electrode yields a different reference potential and therefore a different zero-point on the potential axis. Method parameters are always given relative to the reference potential. To be able to measure using the Ag/AgCl reference electrode, you just need to adjust all potentials by the potential difference between the reference electrode described and the Ag/AgCl reference electrode.

The table shows the potentials of some common reference electrodes measured against a standard hydrogen electrode.

Reference electrode	Potential compared to SHE (standard hydrogen electrode at 25 °C)
Ag/AgCl, c(KCl) = 3 mol/L	+207 mV
Ag/AgCl, c(KCl) = 1 mol/L	+236 mV
Hg/Hg2Cl2, c(KCl) = sat. (SCE – saturated calomel electrode)	+241 mV
Hg/Hg2Cl2, c(KCl) = 1 mol/L (NCE – normal calomel electrode)	+280 mV
Ag/AgCl, c(KCl) = 0.1 mol/L	+291 mV

The figure shows the signal “shift” resulting from different reference potentials. 

MISP method to remove the unwanted cationic matrix from the sample.

The sample is injected into a stream of transfer solution (generally ultrapure water). In the sample preparation module, the cations are removed from the sample and replaced by H+, Na+, or other non-critical cations (same reaction as in suppression). The analyte ions are retained by the preconcentration column and then injected for analysis.

Typical applications: Removal of heavy metals from galvanic samples.

In exceptional cases, the evaluation algorithm cannot calculate results with the "Nonlinear regression technique" curve type. You should be able to solve the problem by selecting the "Linear Interpolation" curve type.

You can find video sequences and more information to assist you with the maintenance and care of your Metrohm IC system here:

Product Help: IC Maintenance

All connections between the injector, column, and detector must be as short as possible and absolutely leak-proof. Furthermore, they should have the smallest possible dead volume. We recommend PEEK capillaries with an inner diameter of 0.25 mm for these connections. The PEEK capillary downstream of the detector block must not have any constrictions (the measuring cell is designed for a backpressure of up to 5 MPa = 50 bar). In order to ensure an optimum backpressure, it must not be shortened.

Yes. tiamo runs in a protected Java environment. If possible, the requirements in the installation instructions should be met.

In cases of samples with low solubility, one of the following procedures is recommended:

A) Use of a solubility promoter

Volumetric KF titration

Solvent	Percentage	Samples
Formamide	max. 50%	Sugar samples, salts
Chloroform	max. 70%	Oil, grease
Long-chain alcohols	max. 50%	Oil, grease
Xylene, toluene	max. 70%	Crude oils with tars

Coulometric KF titration

Solvent	Percentage	Samples
Formamide*	max. 20%	Sugar samples, salts
Chloroform**	max. 30%	Oil, grease
Long-chain alcohols**	max. 30%	Oil, grease
Xylene, toluene**	max. 30%	Crude oils with tars

* Only with generator electrode without diaphragm.
** Use generator electrode with diaphragm if the amount of solubility promoter is higher than 10%.

B) Titration at a higher temperature

Temperature	Samples
40 °C / 50 °C	Vegetable samples, salts, fat-containing samples, food samples

C) Mechanical pretreatment

• Homogenizer
• Mortar
• Lab mill (cooled)

These procedures can also be combined with each other. Detailed information as to which procedure is suitable for which sample can be found in the Metrohm KF monograph.

Undersized peak areas often indicate that the sample quantity is too small.

• There is a leak in the sample path: Check the sample path.

• The sample path is blocked: Check whether the sample is flowing during filling of the sample loop. If the sample flow rate is too low or zero, check the settings and then look for the blockage in the sample path and remove it.

• The sample loop is not completely filled: Adjust the transfer time.

• There are gas bubbles in the sample: Use the sample degasser.

• The MCS (CO2 suppressor) is not connected: Connect the MCS and check the CO2 cartridge.

• The high-pressure pump has contaminated valves: Clean or replace the pump valves.

• The high-pressure pump has defective piston seals: Replace the piston seals and, if necessary, the pistons.

Select the determinations of these standards in the "Database" as well as all determinations of samples that are to be recalculated.

In the "Determinations" menu, select "Reprocessing…" or click the corresponding icon.

Select one of the standards in the "Reprocessing table" and correct the entries in the component table. Clicking "Update" applies the changed parameters to the selected determination. The peaks in the chromatogram are now correctly labeled.

Select "Reprocessing" and then the option "From the standards of the reprocessing table". All the determinations are recalculated using the parameters of the selected line.

If the result of the reprocessing is satisfactory, save the reprocessed determinations by closing the reprocessing window with "OK".

Select the determinations of these standards in the database.

In the "Determinations" menu, select "Reprocessing…" or click the corresponding icon.

Select the standard with the required calibration; this is generally the last determination.

To reprocess, select the option "Of the marked determination".

If the result of the reprocessing is satisfactory, save the reprocessed determinations by closing the reprocessing window with "OK".

The procedure for further problems during "Reprocessing" is described in the online help under "How to proceed?".

This can happen if the two PCs do not have the same time zone and summer time / winter time settings. The precise global time is displayed. If it is 12 noon in Bern, then it is 6 a.m. in New York.

This should not actually be the case, but if this situation does occur there are very differing reasons.

The tiamo database path should be defined as an exception in the virus scanner, so that this path is not scanned. Furthermore, no backups should be created when you want to use the system.

The more databases there are, the longer it will take to open the «Open database» dialog or the database manager. The reason is that all databases first have to be opened and all the information (e.g., size) has to be read out before everything is displayed.

Use of powerful hardware, e.g., a RAID-5 system, is always recommended.

There should be at least enough sample in the reaction vessel so that the air tube is still submerged in the sample at the end of the measurement. That is the case for a volume of approximately 2 mL and above.

There should only be as much sample in the reaction vessel so that the entire sample fits in the heated section of the heating block. That is the case for a volume of up to approximately 12 mL.
In most applications, between 3 and 7.5 g of the sample are used.

• A side reaction is taking place. Read for more details in the following FAQs: «How to recognize a side reaction?», «How to prevent side reactions?»
• The cell is not leak-tight. In this case carry out the following measures: replace molecular sieve, O-rings/PTFE sleeves, and septum.
• There are deposits on the indicator electrode. Read for more details in the following Installation FAQ: «How to clean the indicator electrode?»

1. Check the sample size.
2. Check whether the titer and concentration of the titrants are correct.
3. Check the calculation formula in the method. Is the correct equivalence point used for the calculation?
4. Check the endpoint recognition criteria (ERC). An ERC that is too small can result in an incorrect equivalence point. 
5. Check that the anti-diffusion tip is functioning correctly.
6. Check the stirring direction. The titrant should not be stirred directly onto the electrode, but rather away from it.

Jumps in the measurement curve are generally caused by gas bubbles adhering and suddenly detaching from the conductivity measuring cell. This tends to occur during longer measurements and if the sample gets into the measuring cell via the gas phase and settles in the conductivity measuring cell there. Individual or a combination of various countermeasures can be taken to improve the curve shape.

• Take measurements at a higher sample temperature to reduce measuring time.
• Take measurements at a lower sample temperature so that less of the sample evaporates, meaning that less of the sample can precipitate on the conductivity measuring cell.
• Use long reaction vessels (250 mm, 6.1429.050) with a long air tube (248 mm, 6.2418.130). The upper part of the reaction vessel located outside the instrument serves as a condensation trap, therefore reducing the amount of sample that can get into the measuring vessel.
• Using the oil separator (6.2753.200). The oil separator functions according to the principle of a cyclone separator and is mounted between the reaction vessel and the measuring vessel. It reduces the amount of sample that gets into the measuring vessel.

No chloride is contained in the VMS: Check the preparation of the VMS and modify if necessary.

• AOCS Cd 12b-92 «Sampling and analysis of commercial fats and oils: Oil Stability Index»
• ISO 6886 «Animal and vegetable fats and oils – determination of oxidation stability (accelerated oxidation test)»

A "Timer" is available in MagIC Net. This can be used to define single or recurrent "Tasks" that are to be started at a certain time or date/time.

The available "Actions" are: "Start equilibration", "Start sample table", and "Stop devices". This can be used, e.g., to start the IC system early enough in the morning so that the system is already equilibrated when work is started.

• High-quality and high-purity mercury is needed for polarography, minimum w(Hg) = 99.999%.
• Only fresh, clean, and dry mercury must be used in polarography.
• Do not reuse mercury.
• If applicable, remove the black oxide layer from the mercury prior to use.

MIDT can be used to automatically dilute the sample according to a preset dilution factor.

A Dosino is used for handling the liquids. In addition to automatic calibration using one standard solution, logical dilutions can also be carried out. This means that MagIC Net checks whether all the results lie within the calibration range. If this requirement is not met, dilution is triggered once again, followed by injection with an adjusted dilution factor.

iColumns are intelligent Metrohm IC separation columns. They are equipped with a column head that is fitted with a microchip. The head is used to secure the column to the appropriate holder in the IC instrument. The system immediately reads out all the column information, such as type, dimensions, number of injections, date of first use, etc.

The 800 Dosino is a universal tool for Liquid Handling. It can be used not only for simple transfer of solutions, but also for dosing quantities with a µL accuracy. Typical applications include sample transfer, MSM regeneration, rinsing, eluent preparation, Dose-in Gradient, and accurate sample dosing for sample preparation techniques such as MiPT, MiPCT, MIDT, etc.

If a method is reloaded, the statistics series will be reset. A method is also reloaded if you reload the same method, even though it is the same method. The method is also reloaded if you switch from the Single Determination tab to the Determination Series tab or vice versa.

The original method of regenerating the MSM is based on feeding the regenerating solution using a peristaltic pump. It is also possible to use a Dosino that is specially reserved for this purpose. Dosino Regeneration uses a defined volume of regeneration solution for each procedure. This allows control of the volume and prevents it running empty.

The sample has been contaminated before the sample was injected. Check the sampling procedure and the cleanliness of the sample vessels.
Carry-over from the previous sample has occurred. Increase the rinsing and transfer times.

In the past, there was a possibility to "package" the program 'BackupServer.exe' as service with Windows on-board resources: (Instsrv.exe and Srvany.exe). However, these tools are no longer provided by Microsoft since Windows 10 / Windows Server 2008.

It is possible to convert the application 'BackupServer.exe' as a service with specially designed commercial programs.  The program "FireDaemon Pro" was used successfully with several Metrohm customers, including in the pharmaceutical sector:

https://www.firedaemon.com/firedaemon-pro

There are several other commercial suppliers on the internet providing such solutions.

After successful conversion of the 'BackupServer.exe' as a service, please note:

• The requirements for the backup (access rights, sufficient memory space, firewall settings) must be met
• Start the service and manually create an initial backup
• With each repair of tiamo, please check afterwards if 'BackupSever as a service' is still working

In the event of problems, there is often a mismatch of the stipulated rights.

The Metrohm Suppressor Module (MSM) has 3 suppressor compartments that are in turn used for suppression, are regenerated or are rinsed. To ensure that each new chromatogram is recorded under comparable conditions, every analysis is carried out with a freshly regenerated suppressor compartment. The change-over from one suppressor compartment to the next is carried out automatically between the chromatograms. Operation of the Suppressor Module requires a peristaltic pump or a Dosino (Dosino Regeneration) to transport the regeneration solution to the suppressor compartment. In the usual STREAM process, the detector effluent is used to rinse the regenerated suppressor compartment. Alternatively, ultrapure water can also be used as the rinsing medium (via a Dosino or a peristaltic pump). The suppressor should always be regenerated against the eluent flow direction. Therefore, you must install the suppressor in accordance with the labeling on the connecting piece. The Metrohm Suppressor Module must never be switched over when dry because it may jam. The capacity of the suppressor compartments depends on the eluent and flow rate and is exhausted after about 1–2 hours or even earlier. If there are extended pauses between the individual measurements, we recommend using the Autostep function of MagIC Net that automatically changes over the MSM, e.g., at intervals of 10 min.

The determinations (raw data, evaluation, method, calibration, etc.) are stored in a database. If a determination is reprocessed and saved again, a new version is created that retains all of the original data.

The original version can be reactivated at any time. Irrespective of the MagIC Net settings, the current and the original versions or all saved versions are available. In the latter case, each of the older versions is updated.

The data chip of the dosing unit is mechanically damaged or impaired by chemicals:

• Remove the dosing drive and attach it again.
• Clean the data chip and the contact surfaces.
• Have the data chip replaced by Metrohm Service.

Adjustments and changes made in "Reprocessing" for a series of determinations are only valid for these determinations after closing with "OK".

If these changes are to be applied to the current method, they must be saved in the "Reprocessing" window.

Automatic preparation of eluents for continuous IC analyses over several weeks. The 941 Eluent Production Module is used to produce eluents "as required".

If the separation properties of the separation column have greatly deteriorated, it can be regenerated in accordance with the manufacturer's instructions. The regeneration conditions for columns supplied by Metrohm are given in the accompanying column leaflet or in the Column Catalog.

The separation column should be regenerated only if rinsing with a strong eluent does not improve the separation properties.

The driving axle is defective and needs to be replaced.

Because PTFE capillaries are soft, do not tighten the screws too much. If the capillaries are nonetheless pinched, cut off the first few millimeters with a capillary cutter. Do not operate the suppressor in a dry condition! If the background conductivity is too high, check the flow rates of the regeneration solution and the rinsing solution.

Contact problem at the driving axle (6.1204.x10 or 6.1204.x20): Remove any abrasion residue from the driving axle. If necessary, replace the driving axle.

We do not recommend the use of a screen saver.

It is difficult to make a general statement. The frequency of titer determination depends on a variety of different factors:

• leak-tightness of the titration system
• selection of the titrant
• humidity in the laboratory
• changes in room temperature
• requirements regarding exactness of the result

In principle, we recommend that titer determination should be carried out daily in the presence of high requirements concerning exactness. If no relevant changes are found, then the frequency can be reset to weekly. It should be noted that in general the titer of one-component reagents drops faster than that of two-component reagents.

To prevent contamination of the Suppressor Module by foreign particles and bacterial growth, it is necessary to install the 2 µm Inline Filter (6.2821.120) contained in the scope of delivery between the peristaltic pump and the inlet capillaries of the Suppressor Module.

All MagIC Net versions incorporate a comprehensive user management that enables operation in full compliance with these rules and regulations. The minimum conformity settings can be activated with one mouse click.

Yes.

The molecular sieve can be regenerated at 300 °C in the drying oven. The regeneration time is at least 24 hours. The molecular sieve is then placed in a desiccator for cooling down and afterwards stored in a glass bottle with an airtight seal.

• Brochure: Mercury Handling Guidelines
• http://en.wikipedia.org/wiki/Mercury_poisoning
• https://www.who.int/teams/environment-climate-change-and-health/chemical-safety-and-health/health-impacts/chemicals/mercury
• http://www.epa.gov/mercury/
• http://ec.europa.eu/environment/chemicals/mercury/index_en.htm

There are two kinds of databases: configuration databases (ConfigDB) and determination databases.

They can easily be copied (e.g., onto CD-ROM for backup purposes) and restored at the new location.

However, please note the following: If the databases are opened, they are blocked for processing (deleting, overwriting, copying, etc.). ConfigDB is always opened by the tiamo services (Metrohm tiamo Admin Server and Metrohm tiamo server) − the other databases are opened only if tiamo or a backup is running.

Therefore, tiamo must be closed, and the backup server and the tiamo services must be stopped before you carry out any file operations. Bear in mind that for normal users the paths made available by tiamo (backup and restore) should be used.

The tiamo installer carries out adaptations for the following directories:

• %ALLUSERSPROFILE%\Application Data\Metrohm (with Windows 2000 and XP this directory is typically to be found here: C:\Documents and Settings\All Users\Application Data\Metrohm),
• %PROGRAMDATA%\Metrohm (Vista or higher: this directory is typically to be found here: C:\Program Data\Metrohm)

Namely as follows:

• The owner of the directory \Metrohm (and subordinate directories) is the administrator group.
• Full rights to the directory \Metrohm (and subordinate directories) for the following user groups: Administrators, SYSTEM, Power Users, Users, and Guests.

The aim of this adaptation is for a Metrohm directory to exist under the profile directories that all users can access. This is where the log files, temporary files, exported and archived audit trails, and, depending on settings, the actual databases and their backups are stored. This shows that tiamo can only work if each user can access this data.

The electrolyte vessel can be filled with any electrolyte that is a good conductor. If potassium interferes with the determination, you can use NaCl, for example, instead of KCl. However, you should not change the electrolyte in the internal reference system. Using a different electrolyte here instead of c(KCl) = 3 mol/L changes the reference potential. This is also the case if you are using a different concentration of KCl.

The room temperature and/or the solution temperature are not constant: The room and solution temperature should be kept stable during the measurements (± 4 °C).

The reference potential is drifting away: Maintenance of the reference electrode should be carried out in accordance with the electrode leaflet.

The measuring vessel and the electrodes have been contaminated with organic additives. Thoroughly rinse the measuring vessel and the electrodes and use fresh VMS.

A. The electrodes were lifted out of the measuring solution when the sample was added. Please use the pipette opening for sample addition.

B. The temperature is instable.

This entry is not made until correct and complete backup has been executed.

Current sample data under "Single determination" and "Determination series" can be checked with the "Run test for determination(s)" (green check mark or under the "Tools" menu). This checks whether the sample data are complete, whether the required devices and components are available, and whether the method is plausible.

Specifications always apply incl. subfolder and only with NTFS as the file system.

• Modify right for SYSTEM users for the data and backup directory (it suffices for operation of the database, but backup can no longer be performed with it – for this you also need Write rights for the logged-on user {see further below}).

• Modify right for logged-on user for
   - %ALLUSERSPROFILE%\Application Data\Metrohm (2000, XP) and %PROGRAMDATA%\Metrohm (Vista, 7) (for the user groups Guests, Users, System, and Administrators this is taken care of during installation). With Vista / Windows 7 the path is C:\Users\All Users\Metrohm.
  - All directories used by tiamo (Data, Backup, Import, Export, PDF Reports, etc.)
  - Desktop

• Read & Execute right: logged-on users need these rights for the tiamo folder

• No special rights in the registry

NB: The SYSTEM user does not in every instance have the requisite rights on the network drive (e.g., with Novell networks). Backups in particular are often and preferably carried out on network drives! NB: Windows Explorer can be opened from tiamo (e.g., Audit Trail). This is important for customers who do not have access to Windows Explorer. The following chapters are also important in this context: “Which adaptations and changes does the tiamo installer carry out during installation?” and “After installation user rights were different, in that the user logged on during installation has full (or special) rights.” under Installation (see below).

The electrolyte vessel can be filled with any electrolyte that is a good conductor. If KNO3 interferes with the determination, you can use diluted H2SO4, for example, instead of c(KNO3). However, you should not change the electrolyte in the internal reference system. If another electrolyte is used here instead of c(KCl) = 3 mol/L, then the reference potential changes. This is also the case if you are using a different concentration of KCl.

Possible cause: fault in the electrode setup

1. Check whether the electrode is connected to the correct measuring input and that the electrode is properly assigned in the titration method.
2. Check whether the sensor and/or measuring interface is functioning correctly – for example, by calibrating the sensor or titrating a standard substance.
3. Check the electrode cable by moving it during a measurement and/or titration.
4. Check whether there are other significant electrostatic influences in the measuring area.

Possible cause: error in the application

1. Check whether the electrode in use is suitable for this application.
2. Check whether the stirring rate is adequate. As a general rule, it should be as high as possible. However, try to avoid the formation of a vortex during stirring.
3. Check whether there are any air bubbles in the measuring vessel and/or on the sensor during photometric titrations.

Temperature correction serves to compensate for cooling caused by the gas flow and to offset heat lost when heat is transferred between the heating block and the reaction vessel. 

This value can either be taken from a table or can be determined using the software wizard «Determine temperature correction ...» using the optional accessory for determining temperature correction (6.5616.100 or 6.5616.110). 

We recommend that you determine the precise temperature correction value, especially if results from different instruments are to be compared. Detailed information on determining the temperature correction can be found in the software help and the instrument manual.

Use the foam barrier (6.1451.010). This prevents the foam from getting into the transfer tubing.

Note! You must ensure that the foam barrier is fitted in the upper half. The foam barrier can melt if it is too deep in the heating block during the measurement.

Commands requiring Read or Write access to databases (both determination and configuration databases) are only executed if the database is accessible.
If the database (the server) is not available, e.g., if the line is overloaded, tiamo will wait until the connection is restored. Thus, no data will be lost.

Dismantle the dosing unit as described in the manual for the "807 Dosing Unit" and clean the parts with ultrapure water. If a dosing unit is not being used, rinse it with ultrapure water and drain it.

Video: How to clean the dosing unit

Conditions enable MagIC Net to make decisions automatically. They can be used to decide, e.g., whether a subprogram is executed or skipped.

Variables can also be compared and, depending on the result, different processes can be triggered. This allows a decision, e.g., on the basis of a comparison of the peak areas of the sample and a standard whether a sample has to be diluted further and then analyzed again.

Operating the Multi-Mode Electrode or the Multi-Mode Electrode pro and deaerating the measuring solution require high-purity nitrogen of quality 4.5 (w(N2) = 99.995%) or 5.0 (w(N2) = 99.999%).

"Common variables" are variables (number, texts, date/time) for determinations that must be stored externally (outside the determination), e.g., a counter that has to be applied to the next determination.

"Common variables" have an initial value. This is read out by a determination and can thus be used. The content of a "Common variable" can be changed and then stored again in a determination. The new value is then available for the next determination.

The balance should have a minimum resolution of 0.1 mg.

A default database, "MagIC Net", is created during the installation of MagIC Net. If nothing is changed, the determinations are stored in this database by default.

However, in case of large data volumes, we recommend storing them in different databases. You can freely choose how to organize your determinations (e.g., according to date, project, etc.). The "Method" specifies the target database in which the determinations obtained with this "Method" are to be stored.

Databases can be created, renamed, or deleted under "Database manager".

If Liquid Handling of the sample solution is carried out with a 800 Dosino, care must be taken to prevent any sample from entering the cylinder of the dosing unit. This is achieved by installing a transfer tubing with an appropriate volume upstream of the 800 Dosino and using only ultrapure water as the transfer solution. If the 800 Dosino is only used to fill the sample loop, it must be placed downstream of the injector so that the sample is aspirated through the sample loop. This avoids the risk of any carryover.

There are various ways of determining limits of detection. In the case of a linear calibration, MagIC Net calculates the limit of detection for each component from the calibration function. The value of the limit of detection is provided as a variable (LDTCCONF95). The formula for calculating the limit of detection is given in the online help of MagIC Net.

To operate the Multi-Mode Electrode and the Multi-Mode Electrode pro reliably, a constant nitrogen pressure between 1.0 and 1.2 bar (14.5 and 17.4 psi) is required.

Crystals have formed (in the dosing cylinder, on the valve disk or in the capillary):

• Check the flow path.
• Rinse the dosing unit and the connected tubing and capillaries (prepare function) when the measuring system is not in use.
• Clean the dosing unit at least every two weeks.

Global − the following data is global, i.e., visible in all clients: methods, determinations, export templates, report templates, audit trails, sample tables.

Client-specific − the following data is client-specific, i.e., only visible in the client in question: configurations, views, ID text templates, sample allocation tables.

NB: The data, including client-specific data, is always stored in the database on the server.

The recovery rate can be calculated if a determination of the sample type "Spiking" is carried out after the "Sample".

The concentrations of the spiking solution are defined in the method. More than one spiking solution can be defined.

There is a leak in the system. Please check all connections.

There are a number of possible reasons for a pressure increase in the system. First of all, find out the location of the pressure increase. The best way to do this is to remove one system component at a time from the flow path, starting from the eluent outlet, and check the measured pressure difference. The component causing the pressure increase must then be serviced or replaced. Typical components that can cause a high backpressure are:

• The Inline Filter (6.2821.120): The filter disk (6.2821.130) can be replaced.

• The guard column: Replace the guard column.

• The separation column: Regenerate the separation column according to the column leaflet (should be carried out only if the separation or peak shapes are affected as well). Note: Separation columns should always be operated with a guard column. Samples should always be microfiltered.

• The injector: If the increased backpressure is caused by the injector, you should have it cleaned by a Metrohm Service technician.

The solutions should be protected from direct sunlight. If possible, the solutions should be stored in glass vessels. Unless specified otherwise, additives should be stored at room temperature.

The working electrode needs to be cleaned. Carry out a conditioning procedure in pure VMS. If applicable, the electrode needs to be cleaned.

The conductivity of the deionized water should not exceed 20 µS/cm. If the value measured at the start of the measurement is higher than this, it is indicative of a problem with the conductivity measuring cell. This is generally caused by the electrode being contaminated with sample residue. To avoid this, the measuring vessel and the conductivity measuring cell should be cleaned thoroughly after each determination (see Cleaning after the determination).

Our electrode finder helps you to find the ideal electrode for your titration in just a few clicks.

Go to the electrode finder

In the safety settings, under «Logoff» the option «No processing of workplaces in the BUSY status» must be ticked.

The following prerequisites must be met for the backup function to work:

• BackupServer.exe must be running (check in Task Manager).
• On the server (tiamo multi license) or on the client (tiamo full or light license) a user with appropriate rights must be logged on and remain in Windows.
• This user plus the system user need at least Modify rights for the backup and database directories.
• In the backup directory there must be sufficient space free to create a new copy of the database. The old backup will not be deleted unless this copy has been created. tiamo will thus temporarily need more space.
• The firewall settings must be correct (see «General»).

The reference electrode is not yet equilibrated: After maintenance of the reference electrode, wait for at least 20 min before starting a measurement.

The platinum electrode tip is contaminated: Condition the working electrode in pure VMS.

The platinum electrode tip has been used for a very long time: Immerse the platinum electrode tip in c(NaOH) = 0.5 mol/L for approx. 10 min and then thoroughly rinse with distilled water. Replace the platinum electrode tip if necessary.

The VMS is contaminated: Check whether the reagents are clean. Only reagents with degree of purity "analytical grade" or better should be used.

The water quality is poor: Use distilled water, type-II grade (ASTM D1193-91) or higher.

The measuring solution is contaminated by diffusion: No infeed tubing other than the four-way micro dosing tip (6.1824.000) may be immersed in the measuring solution.

The electrode surface of the Ultra-Trace electrode can be regenerated with the special polishing set, art. no. 6.2802.020.

The cell constant of the conductivity measuring cell used in the Rancimat lies between 1.0 and 1.2 cm-1. For measurements in which the induction time is to be determined, more precise calibration is not required, as only the relative change in conductivity is evaluated in the case of the induction time.

If, however, the stability time is to be determined, in which the absolute change in conductivity is evaluated, we recommend that you determine the cell constants. You can find more detailed information on working with calibrated conductivity measuring cells and determining the cell constants in the manuals for your instrument and the software used.

The columns may only be used in the flow direction. A guard column should always be used. This must be replaced at regular intervals (in the case of a Metrosep RP 2 Guard, only the filter and the frit may need to be replaced). To increase the service life of a separation column, check, e.g., the quality of the chemicals used, the water, and sample preparation (e.g., filtered or dialyzed samples).

The electrolyte vessel can be filled with any electrolyte that is a good conductor. If chloride interferes with the determination, you can use KNO3, for example, instead of KCl. However, you should not change the electrolyte in the internal reference system. Using a different electrolyte here instead of c(KCl) = 3 mol/L changes the reference potential. This is also the case if you are using a different concentration of KCl.

The temperature is the measuring parameter that has the greatest effect on the end result (induction time, stability time). If the temperature is not prescribed by a standard, the sample temperature should be selected in such a way that the result lies between 4 and 10 hours.
As a general rule:

• If the sample temperature is increased by 10 °C, the induction time halves.
• If the sample temperature is decreased by 10 °C, the induction time doubles.

Technical poster

8.000.6081 (Determination of the oxidative stability of biodiesel (fatty acid methyl esters, FAME))

A Method is used to define what, how, and when something is carried out and determined.

In MagIC Net, the method is composed of four windows.

"Devices" shows all instruments and modules used in the method along with their parameters. Clicking on the corresponding icon opens the parameters of this component so they can be adjusted.The "Analysis" is also created in this window. "Hardware assignment", "Data acquisition", and "Accessories" are defined here. The window "Evaluation – Components" has the sections Integration, Analysis Components, Standards, Calibration, and Results. Under "Results", it is possible to define "User-defined results", "Statistics", "Monitoring", etc. The third method window, "Time program", defines the exact analysis run. This defines all steps that the IC system or MagIC Net must execute. A time program can comprise a few consecutive steps or complex interleaving of subprograms. The fourth window shows the last chromatogram with the current calibration.

Both the Multi-Mode Electrode and the Multi-Mode Electrode pro can be operated using a maximum of 6 mL mercury (roughly equal to 81.2 g). This amount is sufficient for approx. 200000 drops.

Separation columns that are not being used must always be sealed and filled in accordance with the manufacturer's instructions before being stored. If there is no information available, the separation column should be stored in a refrigerator at 4–8°C

The electrode cable has accidentally been jammed in the measuring head cover or a cable contact has been bent: On the 894 Professional CVS you can replace the electrode cable set (see 894 Professional CVS manual). On the 797 VA Computrace this needs to be handled by Metrohm Service.

You can prepare your own standard solutions from the appropriate salts or you can buy them directly from a chemicals supplier.

Please check that the pH value of the solutions is suitable for the respective separation columns. Standards and reagents especially for ion chromatography can be found for example here

All Metrohm Service technicians must undergo extensive service training and are certified by specially qualified trainers. Metrohm Service technicians have a corresponding service pass that is valid for two years.

Results may be too low for the following reasons:

 

Cause	Remedy
Side reaction	Read for more details in the following FAQ: «How to recognize a side reaction?», «How to prevent side reactions?»
The sample is inhomogeneous	Increase the sample size. Homogenize the sample prior to the determination.
The sample dissolves incompletely	Read for more details in the following FAQ: «What can I do to improve the release of water?»
The pretreatment of the sample is not optimal.	Read for more details in the following FAQ: «What to do to improve the release of water?»
Titer is incorrect (volumetric KF titration)	Redetermine the titer with certified standards.
Titration stops too soon	Reduce Stop Drift or work with a relative Start Drift.
The sample gives off water even during sample preparation	Here we recommend optimizing the sampling and sample storage, as well as rapid working during the determination sequence.

Trend within the results

One reason for decreasing water contents in a series may be that the solvent is exhausted and must be replaced. Decreasing water contents within a series can also occur with samples which give off water during sample handling. Here we recommend optimizing the sampling and sample storage, as well as rapid working during the determination sequence.

A further possible reason for apparently decreasing water contents within a series in volumetric Karl Fischer titration is that the buret has not been prepared. The titrant in the cylinder and in the tubing is exposed to humidity, which can result in increased titrant consumption at the beginning of a series.
Increasing water contents within a series can occur with hygroscopic samples. Here we recommend optimizing the sampling and sample storage, as well as rapid working during the determination sequence.

Tip: You can recognize very quickly whether your sample is either releasing water, is hygroscopic, or unproblematic by determining the water content of the sample immediately and then leaving the sample to stand in a beaker in the laboratory air and determining the water content again after 10, 30, and 60 minutes.

Up-to-date information on the compatibility of MagIC Net with the individual Windows™ versions can be found in the Metrohm Software Center.

This effect is not uncommon. It is caused by degradation products in the bath sample. With successful determination of recovery in a "check standard", the method can be checked at any time.

We advise against mechanical treatment of platinum electrodes, e.g., by polishing with aluminum oxide!

If a titrator with Dosing Unit is not used for several days, then it is best to empty the Dosing Unit with the «Empty» command. In this way, you will avoid the formation of crystals in the Dosing Unit, the tubing, and the buret tip (antidiffusion valve).

If work is being done with an Exchange Unit, then you should immerse the buret tip in methanol in order to avoid crystallization. To accomplish this, you can either fill the storage vessel with methanol or continue to leave the buret tip in the closed cell filled with working medium, where it is immersed in the working fluid.

The Exchange Unit, the tubing, and the buret tip should all first visually inspected for crystals before the system is returned to operation. If crystals are present, then the tubing should be flushed with methanol or ethanol and then dried afterwards.

If no crystals are visible, then a small amount of reagent should nevertheless be dosed in order to check whether crystals have formed in the flat stopcock of the Exchange Unit. If reagent escapes from the flat stopcock, then the Exchange Unit must be disassembled and cleaned (see manual for the Exchange Unit).

Afterwards, flush the Exchange Unit by means of the Preparation/«Prep» command in order to make it ready for operation again.

With local installations (light and full) such problems can occur if the processor load is constantly high (>80%). This situation, however, is unusual, and therefore the on-site administrator should check why the processor is so overloaded. Normally the processor workload is >10%, with load peaks in between.

With a multi system the reasons for this may vary: server load very high, the network is unstable, above all under load (low response times), the network connection has briefly been interrupted.

The cables are not connected or not connected correctly:

• Connect the cables in accordance with the instructions in the manual.

The tubing connections are leaking:

• Check the tubing connections and tighten, if necessary.

The rinse and/or waste canister are sealed air-tight:

• Loosen the caps on the canisters a little or remove them.

The peak type of each component peak is determined with a result variable (type). The peak type can be displayed using a user-defined result. The peak type is written as a combination of two or more letters. The first two letters describe the start and end of the peak. A two-letter output shows that the peak was integrated automatically. In case of manual integration, the next letter is an M (e.g. BBM, DBHM, etc.).

Most likely, the VMS in the measuring vessel is contaminated. The contamination might have been caused by the chemicals used but also by organic additives.

The analytical quality attainable with Metrohm IC chiefly depends on the separation of the ions of interest on the deployed column.

When buying an IC column, you should make sure that it provides sufficient separation for the intended analytical samples. You can assess this using the reference chromatograms in the Column Catalog.

If problems should occur during your analyses, the first step is always to check the quality of the column and record a standard chromatogram. Compare the data on the column leaflet, e.g., retention factors, selectivity, number of plates, and resolution, with your own measurements.

Further information on handling IC separation columns is given in the brochures supplied with the column, in the Column Catalog, or in our column finder.

Column Finder

Yes. See also «The more data there is, the slower tiamo becomes», under Databases in general.

Statistics functions are available in the method for multiple injections. They can be used to calculate the mean value, the absolute and relative standard deviation as well as the minimum and maximum value of a "Result".

The problem can be rectified as follows: Go to the Windows system properties and select «System performance». Then select the «Expand» tab and click on [Settings]. The «Performance options» dialog will then be displayed. Select the «Visual effects» tab and deselect the «Show window content when dragging» checkbox.

The dosing units available for the 800 Dosino have volumes of 2 mL, 5 mL, 10 mL, 20 mL, and 50 mL. Since the 800 Dosino doses the total volume in 10,000 increments, the unit with the smallest possible volume should generally be used to obtain the highest possible accuracy.

We recommend the following:

• Eluent preparation: 50 mL dosing unit
• MIDT: 10 mL dosing unit
• MiPCT, MiPCT-ME: 5 mL dosing unit
• MiPuT, MiPT, suppressor regeneration: 2 mL dosing unit

Dirty platinum pins can be cleaned with an abrasive agent such as Alox (polishing set, art. no. 6.2802.000) or toothpaste. Afterwards, they should be rinsed with ethanol or methanol. It is often sufficient to wipe off the indicator electrode with a soft paper tissue. This is particularly important when the electrode was immersed previously in an overtitrated solution, because deposits can form there that are not visible but nevertheless lead to overtitrations. If the sample itself adheres to the electrode, clean it off, either with an appropriate solvent or mechanically. Clean the platinum pins on the indicator electrode with a soft paper tissue and take care to ensure that the pins do not become deformed (pressed together) while doing so. They should always be parallel to one another.

Calibration method for very small concentration ranges (ng/L to µg/L) using a standard solution with a higher concentration that is easier to manage. This requires an additional injector and a preconcentration column.

This means that the eluent flow rate is not constant. Possible reasons for this are

• A leak in the eluent path: Eliminate the leak.

• A blockage in the eluent path: Eliminate the blockage.

• Gas bubbles in the eluent: Degas the eluent and check the connectors of the eluent degasser.

• The high-pressure pump has contaminated valves: Clean or replace the pump valves.

• The high-pressure pump has defective piston seals: Replace the piston seals and, if necessary, the pistons.

The "User administration" has three predefined user groups ("Administrators", "Users", and "Removed users").

The only predefined user under "Administrators" is "Admin1". The first-time login as "Admin1" does not require a password. Assignment of a password is then prompted automatically afterwards. Administrators have full access permissions for all functions of MagIC Net, particularly for the exclusive editing of user management. The creation of a second administrator access is recommended so that, if one administrator is unintentionally deleted, the user management can still be edited.

Additional "Groups" can be created in addition to the existing group of "Users". The access permissions, signature permissions, and display standards can be freely assigned to these "Groups". Users created within these groups have the permissions assigned to the group. When a user is created, a start password must be assigned. This is a single-use password so that the user can log in once. The user is then prompted to change his or her password.

Detailed information on the maintenance work described below is given in the manual for your instrument.

Aspiration filter: The aspiration filter should be replaced if it is discolored or at least every three months. Contaminated aspiration filters can lead to pressure and baseline fluctuations.

IC pump: The piston, seals, and valves should be serviced at least once a year.

Inline Filter: The Inline Filter should be replaced if the backpressure increases or at least every three months.

Pulsation absorber: Maintenance is not possible. Defective pulsation absorbers must be replaced.

6-way injection valve: If there are problems with the precision, check the installation of the sample loop. More extensive maintenance should be carried out by a service technician.

Suppressor (MSM, MSM-LC, MSM-HC): If the capacity drops or a high backpressure builds up, the Suppressor Module must be regenerated, cleaned, or replaced.

Detector block (conductivity detector): A blocked inlet capillary can be shortened by a few millimeters. Backflushing with the high-pressure pump may also help. Caution: The pressure must be < 5 MPa. The detector block must not be opened under any circumstances.

Detector cell (amperometric detection): The working electrode can be cleaned and polished as described in the manual. The reference electrodes are maintenance-free. The Ag/AgCl reference electrode must be replaced at regular intervals.

Databases containing a large number of determinations can become very large.

We thus recommend setting up a database management to limit the number and the size of the databases in MagIC Net. Thus databases can be created based on, e.g., weeks, months, projects, sample types, etc.

Databases that are currently not needed can be backed up and deleted from MagIC Net. The data remain as backup copies and can be restored at any time.

MISP method to remove the matrix (unwanted substances in the sample) from the analyte.

The sample is injected into a stream of transfer solution (generally ultrapure water). The analytes are retained on the preconcentration column, and the matrix is then removed using an additional transfer solution. The analytes are injected after this cleaning.

Inline preconcentration is a method in which the analyte is retained on a short column (the preconcentration column).

This preconcentration column is installed on the injector instead of the sample loop. When the injector is switched over, the preconcentrated analytes are sent to the separation column. Preconcentration is mainly used for very low concentrations (ng/L to µg/L range). It enables preconcentration of analytes from large sample volumes. A Dosino (e.g., with a 5 mL dosing unit) can be used in MiPCT setup for preconcentration of 44,000 µL of the sample solution, an automatic multipoint calibration using one standard solution, or a logical adjustment of the sample volume. This covers a concentration range of the samples of 1:1,000,000 (ng/L to mg/L).

If the air tube is always positioned in the same way, the reproducibility of the results improves.

Fitting without foam barrier
If you do not use a foam barrier, we recommend that you position the air tube in such a way that the bottom end does touch the glass wall of the reaction vessel. 

Fitting with foam barrier (6.1451.010)

If you use a foam barrier, the position of the air tube is fixed.

Note! You must ensure that the foam barrier is fitted in the upper half. The foam barrier can melt if it is too deep in the heating block during the measurement.

Accessories

The following accessories are generally used to determine the oxidation stability of biodiesel (B100) and biodiesel blends:

• 6.1429.050 Reaction vessel long (250 mm)
• 6.2418.130 Air tube long (248 mm)
• 6.1428.030 Measuring vessel (glass)
• 6.1839.000 Iso-Versinic tubing

All the accessories required for 100 determinations are included in the scope of delivery of the 893 Professional Biodiesel Rancimat.

 

Standard method parameters
Sample amount	7.5 g
Measuring solution (water)	60 mL
Sample temperature	110 °C
Gas flow (air)	10 L/h
Evaluation	Induction time Automatic (2nd derivative) Optional (manual): tangential method

The electrode surface of glassy carbon electrodes can be regenerated by polishing with aluminum oxide.

The method and the export and report templates are stored in the determination in addition to the data.

Possible cause: fault in the electrode setup

1. Check whether the electrode is connected to the correct measuring input and that the electrode is properly assigned in the titration method.
2. Check whether the sensor and/or measuring interface is functioning correctly – for example, by calibrating the sensor or titrating a standard substance.

Possible cause: fault in the dosing system

1. Check all tubing connections for leaks.
2. Check the buret tip for any signs of blockage.
3. Check the system for air bubbles in the dosing cylinder and/or in the tubing connections.

Other causes

1. Check whether the electrode type in use is suitable for the application.

• MagIC Net Basic: This version is included in the scope of delivery of the 833 Basic IC plus.
• MagIC Net Compact: Version with one license for a sampler and either a Compact IC instrument, a detector, or a data channel (771 IC Interface).
• MagIC Net Professional: Version with one license for any number of devices at four workplaces on one computer.
• MagIC Net Multi: Client/server application with 3 licenses. Additional licenses can be purchased.

1. Check the sample size.
2. Check whether the titer and concentration of the titrants are correct.
3. Check the calculation formula in the method. Is the correct equivalence point used for the calculation?
4. Check the system for air bubbles in the dosing cylinder and/or in the tubing connections.
5. Check whether the stirring rate is adequate. As a general rule, this should be as high as possible. However, try to avoid the formation of a vortex during stirring.
6. Check whether the titration might be too quick. You can use the titration parameters “signal drift” and “min./max. waiting time” to adjust the titration rate.
7. Check whether the sensor is still suitable for the titration. Sensors that are old or dirty can result in longer response times.

The data is always (even with local installations, i.e., light or full) transmitted unencoded via a TCP/IP interface.

The auxiliary electrode can be immersed for a few seconds in concentrated nitric acid to oxidize an accidentally applied metal coating. If after another measurement foreign metal should be found on the surface again, then the method parameters and electrode connectors need to be checked.

The best thing is to create a RAM-Init. on the KF Coulometer.
If this is not possible, then you should reset all process-related settings (under Config) to the default values (Autostart off, Silo off, Start Delay off, all Monitoring to off).

It is advisable to condition the electrodes at least once a day before you start work.

The error is occurring because effective copying is failing.

• In the determination directory, there is a file or a directory with the same name as the intended name for the restored database.
• A directory with the name of the restored database could not be set up. (The BackupServer is possibly not started as a result of insufficient rights of the user logged onto the server.)

For the following devices (with mainboard series 16 to 21) updating of firmware using tiamo 2.x is not possible:

• 814 with firmware up to and including 5.814.0023
• 815 and 864 with firmware up to and including 5.815.0024
• 855 with firmware up to and including 5.855.0012

tiamo 1.x and FlashBurn (devices updated with FlashBurn) are not affected. The following firmware versions take the error into consideration, i.e., as from this version updating of firmware is again possible:

• 814 from version 5.814.0024
• 815 and 864 from version 5.815.0025
• 855 from version 5.855.0013

With tiamo 2.3, however, this problem has largely been rectified.

• Use of so-called K-reagents with samples that contain ketones and aldehydes.
• Methanol-free reagents when the sample reacts with the methanol of the reagent.
• When the sample causes a pH shift to the acid range, buffering can be accomplished with solvent and imadazole.
• When the sample causes a pH shift to the alkali range, adding approx. 5 g salicylic acid or benzoic acid to the working medium helps to adjust the optimum pH range for the KF reaction.
• To suppress the side reaction, peroxides can be titrated under cold conditions, e.g., at –20 °C to –60 °C (set Ipol to 5 µA).
• If the sample (e.g., motor oil) contains various substances that react directly with the KF reagent, then a KF oven will be of help.

You will find more detailed information as to which procedure is suitable for which sample in the Metrohm KF monograph.

Auxiliary, reference, and working electrodes should be stored in distilled water. Storage in VMS is not recommended. If the measuring system is not used for an extended period (>24 h), then the reference electrode should be stored separately in c(KCl) = 3 mol/L. The other electrodes can also be stored dry.

No, the platinum electrode tip may not be treated in an ultrasonic bath. This will irreversibly damage the electrode.

With manual evaluation, the EP is set in the corresponding coordinates selected (in this example the y1 axis represents ERC and the x axis represents volume). In the graph view of the determination, this EP is only visible if ERC has been selected as the y1 axis and volume as the x axis. Because the reading is usually selected as the y1 axis, the manually set EP «disappears» (is not displayed).

If the sample cannot be weighted directly into the reaction vessel, it must be melted carefully in the water bath beforehand.

The temperature of the water bath should only be slightly above the melting point of the sample. If the sample is heated too much, it may change in ways that could affect the end result. The sample amount corresponds to the amount that is also used for liquid samples.

For regulatory reasons, registered users cannot be deleted. An administrator can set the user to "inactive" (no access permission) or to "removed".

Users with a "removed" status are shifted from the original group into the "Removed users" group and no longer have access permission.

The solutions used are pipetted manually: The solution can be added with 800 Dosinos with dosing units to obtain reproducible results.

The solutions are not added through the pipette opening: During a measurement the solutions should only be added through the pipette opening.

As a general rule, the auxiliary electrode is maintenance-free and does not require any special cleaning. If you want to mechanically clean the platinum pin, then you can also polish the surface. Make sure that you do not rotate the platinum pin while doing so because otherwise the internal contact may break.

To protect the column against foreign particles that could affect the separating efficiency, we recommend microfiltration of the eluents (0.45 µm filter) and aspiration through the aspiration filter.

Contaminants caused by abraded particles from the piston seals of the high-pressure pump can be avoided by fitting an Inline Filter between the pump and the injection valve.

You can use easily replaceable guard columns to protect the actual separation column and greatly extend its service life.

Samples must be free of particles before they are injected. We recommend filtering all sample solutions through a 0.45 µm filter. Furthermore, Metrohm Inline Ultrafiltration or Dialysis can also protect the column against unwanted components in the sample.

To ensure that MagIC Net operates reliably, all energy-saving functions must be switched off.

The reaction vessels and air tubes are disposable and should not be cleaned and reused. This is because:

• Removing sample residue is extremely time-consuming and therefore costly.
• Cleaning procedures that are typically applied damage the glass. The altered glass surface impairs the reproducibility and accuracy of the results.
• Poorly cleaned reaction vessels lead to scattered and, in some cases, even incorrect results.

A. The reference electrode needs to be maintained. See also Reference electrode.

B. The baseline has not been set correctly. The baseline needs to be defined identically for each addition.

Because with tiamo 2.X the USB driver versions 1.5 to 2.4 are reset, problems with the following software types may ensue (device recognition):

• PC Control 1.0, 2.0, 3.0, 4.0, 4.1 (5.0 not affected)
• Mix Control 1.0, 1.1 (1.2 not affected)
• tiamo 1.0, 1.1, 1.2, 1.2.1 (1.3 not affected)
• MagIC Net 1.0 (1.1 not affected)
• FlashBurn up to 3.1 (3.2 not affected)
• iService 1.0 (1.1 not affected)
• VA 797 version 1.0, 1.1, 1.2, 1.3 (1.3.1 not affected)

To make sure that these software types to continue to work correctly the user must be told to delete the file metr_770.dll in the directory %InstallationPath%\bin (of this affected software). If after installing tiamo 2.x you install one of the above softwares or repair an installation, you must subsequently again delete the file metr_770.dll in the directory %InstallationPath%\bin as above.

It is not possible to repair the driving axle. The driving axle is a consumable and needs to be replaced at regular intervals. Driving axles with a mercury contact are supplied in a bag under protective nitrogen atmosphere. We recommend keeping the storage time of driving axles with a mercury contact as short as possible.

MISP method for inline removal of particles, large molecules, oil droplets of emulsions, etc. from the sample solution prior to injection.

The "Stopped Flow" dialysis method, patented by Metrohm, is based on the diffusion of analyte ions from the sample stream into a stationary acceptor solution. The sample continues to flow through the cell during the dialysis period. Consequently, the sample concentrations in the dialysis cell always remain constant. Equilibrium between the sample and the acceptor solution is attained for practical purposes within a few minutes.

This means that the concentrations of sample ions are almost identical in both solutions. Since there is no pressure difference during dialysis, the driving force is purely diffusion. Thus the risk of blocking the membrane pores is even lower than for Inline Ultrafiltration.

Typical applications: heavily contaminated waste waters, dairy products, fruit juices, emulsions.

• EN 14112 «Fatty acid methyl esters (FAME) – Determination of oxidation stability (accelerated oxidation test)»
• EN 15751 «Automotive fuels – Fatty acid methyl ester (FAME) fuel and blends with diesel fuel»
• EN 16568 «Automotive fuels – Fatty acid methyl esters (FAME) fuel and blends with diesel fuel – Determination of oxidation stability by rapidly accelerated oxidation method at 120 °C»

All kinds of user groups (e.g., administrators, laboratory managers, laboratory technicians, etc.) can be defined in the user administration of MagIC Net.

Each of these groups can be individually assigned access permissions, signature permissions, and other options. Thus every group can be assigned access to precisely those functions that they really need.

 

If the method specifies a Dosino or a device that is connected to a Dosino, a query appears as to whether the Dosino should also be added to the method.

If the answer is yes, the name and use will be queried.

If you select "Suppressor Dosino", the Dosino can be used exclusively for "Dosino Regeneration". In this case, the Dosino is labeled in the diagram with an "S".

If you add a 941 Eluent Production Module, then you can define the Dosinos connected to it as "Eluent Dosinos". "Eluent Dosinos" are labeled with an "E".

Dosinos without a label ("S" or "E") are freely available for Liquid Handling tasks and are always selected as simple Dosinos.

If a Dosino is already defined in a method, it cannot be redefined. In this case, you must remove the Dosino from the method and then add it again as a new device. After you have defined the MSB connector, you can select its use.

 

There is a "Sample table test" available for the sample tables.