FAQ Finder

Yes. In this case, the sample needle must be connected to the two systems via T-piece or both injectors must be installed in series.

First case: If a determination is started on the first system, the sampler is reserved for this system and the other system cannot access it. As soon as the sampler has completed its tasks, it can be released via the "Time program command" "Release". It can now be accessed by the second system. In this case too, the sampler is released after it has completed all its steps and is now available for the next request from one of the two systems. In cases of two injectors connected in series, each of the sample loops can be filled simultaneously or independently of one another.

This is to do with the inherited rights of Windows. Windows automatically puts into the %PROGRAMFILES% directory (e.g., C:\Programs) the group CREATOR-OWNER with the relevant rights. If a new subdirectory is now set up the logged on user will automatically be entered with the rights defined for the above-mentioned group. If you don’t like this, then remove the CREATOR OWNER group. In pre-existent directories the user logged on during the setup of the directory must also be removed.

• 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.

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 measuring head is not correctly locked in place on the measuring head arm: Allow the measuring head to snap into place; you need to hear it click.

The sealing rings have aged or are defective: Please contact us.

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.

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.

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.

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.

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.

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.

Databases can be manually backed up under "Database manager". This can also be used to restore a backup copy of a database.

Every database can also be backed up automatically. This setting is in "Database manager" under "Properties" of the respective database.

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.

Find more information in our Software Center.

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

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.

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.

Method using injection of different sample volumes using partial filling of the sample loop by a Dosino.

A multipoint calibration can be carried out with one standard solution. The injection volume can be adjusted for the sample. MiPT can be used for concentration ranges between µg/L and mg/L. Sample volumes between 2 and 200 µL can be reproducibly injected using a 250 µL sample loop.

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.

A. No sample was added. If requested, add the required sample quantity.

B. The sample does not contain any brightener. Make sure that the sample is fresh. The brightener will volatilize over time.

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

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.

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.

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

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

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).

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.

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.

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.

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.

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 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.

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.

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

The potentiostat integrated in the Metrohm CVS instruments can easily measure the smallest current with a high degree of precision. For this reason, it is also possible to get precise measurement results with smaller platinum electrode tip diameters. In a few exceptional cases, the method parameters need to be adjusted.

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.

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

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%).

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".

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.

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.

tiamo backs up all data in a database − there is no intermediate storage of files.

Files are only created by means of the commands EXPORT (mdet, xml, csv, slk) or REPORT (pdf). This data, however, is secondary data, i.e., copies of the original determination.

The data that ends up in the determination database never undergoes intermediate storage and is thus protected against changes.

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.

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).

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).

Metrohm offers service agreements tailored to your requirements. These range from standard maintenance with a priority response time to full support with an all-inclusive package and a guaranteed response time.

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

 

Solid samples must be broken up before they are weighed into the reaction vessel. The particle size should be as uniform as possible.

Samples of this type are not mixed by the air flow during the determination. Only a small sample amount should be used to avoid a nonhomogeneous temperature distribution within the sample. We recommend selecting the sample amount in such a way that the base of the reaction vessel is covered evenly. A sample amount of 0.5 g is frequently used.

We also recommend using shorter air tubes for PVC (140 mm, order number 6.2418.120) with solid samples.

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.

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).

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

• 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.

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).

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

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)

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

Leading reagent manufacturers offer certified water standards for titer determination. We recommend the use of certified standards. They are simpler to handle, because larger sample volumes can be added here than with titer determination using distilled water.

Standard solutions can be obtained with the water contents 10.0 ±0.1 mg/g and 5 ±0.2 mg/mL, although the latter is not certified.

The possibility also exists of carrying out the titer determination with distilled water or with disodium tartrate dihydrate.