Applikationer

This article demonstrates the utility of portable Raman spectroscopy as a versatile tool for process analytical technology (PAT) for raw material identification, in-situ monitoring of reactions in developing active pharmaceutical ingredients (APIs), and for real-time process monitoring. Raw material identification is done for verification of starting materials as required by PIC/S and cGMP, and can be readily done with handheld Raman. Portable Raman systems allow users to make measurements to bring process understanding and also provide proof of concept for the Raman measurements to be implemented in pilot plants or large-scale production sites. For known reactions which are repetitively performed or for continuous online process monitoring of reactions, Raman provides a convenient solution for process understanding and the basis for process control.

Although the process of building, validating and using a method is well-defined through software, the robustness of the method is dependent on proper practice of sampling, validation, and method maintenance. In this document, we will detail the recommended practices for using the multivariate method with NanoRam-1064. These practices are recommended for end users who are in the pharmaceutical environment, and can expand to other industries as well. This document aims to serve as a general reference for NanoRam-1064 users who would like to build an SOP for method development, validation and implementation.

Raman spectroscopy’s use for process analytics in the pharmaceutical and chemical industries continues to grow due to its nondestructive measurements, fast analysis times, and ability to do both qualitative and quantitative analysis. Spectral preprocessing algorithms are routinely applied to quantitative spectroscopic data in order to enhance spectral features while minimizing variability unrelated to the analyte in question. In this technical note we discuss the main preprocessing options pertinent to Raman spectroscopy with real applications examples, and to review the algorithms available in B&W Tek and Metrohm software so that the reader becomes comfortable applying them to build Raman quantitative models.

In this poster a convenient direct injection suppressed ion chromatographic method for determining chloride and sulfate in denatured ethanol samples according to ASTM D7319 is presented.

Quality and process control of biofuels require straightforward, fast and accurate analysis methods. Ion chromatography (IC) is at the leading edge of this effort. Traces of anions in a gasoline/ethanol blend can accurately be determined in the sub-ppb range after Metrohm Inline Matrix Elimination using anion chromatography with conductivity detection after sequential suppression. While the analyte anions are retained on the preconcentration column, the interfering organic gasoline/bioethanol matrix is washed away.Detrimental alkali metals and water-extractable alkaline earth metals in biodiesel are determined in the sub-ppm range using cation chromatography with direct conductivity detection applying automated extraction with nitric acid and subsequent Metrohm Inline Dialysis. Unlike high-molecular substances, ions in the high-ionic strength matrix diffuse through a membrane into the low-ionic water acceptor solution. In biogas reactor samples, low-molecular-weight organic acids stem from the biodegradation of organic matter. Their profile allows important conclusions concerning conversion in the anaerobic digestion reaction. Volatile fatty acids and lactate can be accurately determined by using ion-exclusion chromatography with suppressed conductivity detection after inline dialysis or filtration.

The analytical challenge treated by the present work consists in detecting sub-ppm quantities of bromide, sulfate, aliphatic monocarboxylic acids and several alkaline earth metals in the presence of very high concentrations of sodium and chloride. Bromide, sulfate, acetate and butyrate can be reliably determined by suppressed conductivity detection. Due to matrix effects, propionate can only be detected qualitatively. This drawback can be overcome by coupling the ion chromatograph (IC) to a mass spectrometric (MS) detector. This results in reduced matrix interferences and significantly enhanced sensitivities. The cations magnesium, barium and strontium are determined by non-suppressed conductivity detection.

Several testing methods such as the determination of the acid and the iodine numbers in biodiesel as well as the quantification of sulfate and chloride in bioethanol are described.

Commercially available fuels are complex mixtures of hundreds of different hydrocarbons. For the calibration of the test engines or advanced experimental and computational research they are modeled by means of multicomponent surrogate mixtures that adequately represent the desired physical and chemical characteristics. By definition, every octane and cetane number corresponds to a specific mixing ratio of primary reference fuels (PRFs). Based on this information, the tiamoTM controlled automatic dosing device prepares the surrogate mixtures. The setup drastically minimizes time-consuming and error-prone manual preparation steps and the contact with hazardous solvents. Additionally, precise and accurate results are displayed on customizable reports that fully comply with all current GLP and GMP requirements.

The presence of copper in fuel ethanol blends has gained considerable attention, since Cu2+ catalyzes oxidative reactions in gasoline leading to a deterioration of olefins and the formation of gum. Anodic stripping voltammetry (ASV), one of the most sensitive and accurate techniques for trace-metal analysis, has been demonstrated for the determination of Cu(II) in ethanol/gasoline blends without any sample pretreatment. Copper ions are first electrodeposited onto the surface of a hanging mercury drop electrode (HMDE) before the amalgamated copper is quantitatively stripped (anodically dissolved), a current-voltage curve being recorded.Experimental conditions such as deposition time and potential as well as the suitable electrolyte and reference electrode were determined in preliminary experiments. For synthetic samples spiked with Cu2+ (5…100 µg/L), recovery rates between 96 and 112% were obtained. The copper-spiked E85 sample provided a recovery of 100%. The relative standard deviations for Cu2+ concentrations of 5 µg/L and above were 8.0 and 5.5% respectively. Using a preconcentration time of 60 s at -0.7 V versus Ag/AgCl, a linear range of 0…500 µg/L with a detection limit of 2 µg/L was obtained.

This poster provides an overview of ion chromatographic methods combined with inline sample preparation for the determination of anions and water-extractable cations in biofuels. In addition, the determination of the oxidation stability is described.

The thermometric titration method presented here permits a simple and direct determination of the total acid number (TAN) in petroleum products. It is an invaluable alternative to current manual and potentiometric methods. Thermometric titration uses a maintenance-free temperature sensor that does not require rehydration and is free of fouling and matrix effects. The procedure requires minimal sample preparation. Results agree closely with those from the potentiometric titrimetric procedure according to ASTM D664, but the thermometric titration method is far superior in terms of reproducibility and speed of analysis, with determinations being complete in approximately one minute.

This poster describes the water determination in different biodiesel samples via direct coulometric titration, the Karl Fischer oven method and an automated KF pipetting system.

Carbonyl compounds (CC) occur in many products, such as bio-oils and fuels, cyclic and acyclic solvents, flavors and mineral oils. Carbonyl compounds can be responsible for the instability of these products during storage or processing. Especially pyrolysis bio-oils are known to cause issues during storage, handling and upgrading. This bulletin describes an aqueous and a non-aqueous analytical titration method for the determination of carbonyl compounds by potentiometric titration.

The determination of the lead content in engine fuels has gained considerable importance since the introduction of the catalytic converter technique. Even small contents of lead interfere with the effectiveness of the catalysts or may destroy them. On the other hand, there are still many vehicles on the roads which run on leaded fuel (addition of tetraalkyl lead). Here also the knowledge of the lead content is of interest.With reference to DIN 51769 and ASTM 0-1269 a simplified procedure for the determination of lead in petrochemical products is described. The products are digested with HCl and the lead compounds are converted to lead(II) chloride. After extraction with water, the inverse voltammetric Pb determination is carried out.

This Application Bulletin gives an overview of the volumetric water content determination according to Karl Fischer. Amongst others, it describes the handling of electrodes, samples, and water standards. The described procedures and parameters comply with the ASTM E203.

This bulletin contains two parts. The first part gives a short theoretical overview while more details are offered in the Metrohm Monograph Conductometry. The second, practice-oriented part deals with the following subjects:Conductivity measurements in general; Determination of the cell constant; Determination of the temperature coefficient; Conductivity measurement in water samples; TDS – Total Dissolved Solids; Conductometric titrations;

Potentiometric titration is an accurate method for determining chloride content. For detailed instructions and troubleshooting tips, download our Application Bulletin.

This Bulletin describes the potentiometric determination of hydrogen sulfide, carbonyl sulfide, and mercaptans in gaseous and liquid products of the oil industry (natural gas, liquefied petroleum gas, used absorption solutions, distillate fuels, aviation gasoline, gasoline, kerosene, etc.). The samples are titrated with alcoholic silver nitrate solution using the Ag Titrode.

This Application Bulletin gives an overview of the coulometric water content determination according to Karl Fischer.Amongst others, it describes the handling of electrodes, samples, and water standards. The described procedures and parameters comply with the ASTM E1064.

As the determination of the exact content of individual glycerides in fats and oils is difficult and time-consuming, several fat sum parameters or fat indices are used for the characterization and quality control of fats and oils. Fats and oils are not only essential for cooking, they are also an important ingredient in pharmaceuticals and personal care products, such as ointments and creams. Consequently, several norms and standards describe the determination of the most important quality control parameters. This Application Bulletin describes eight important analytical methods for the following fat parameters in edible oils and fats:Determination of water content in accordance with the Karl Fischer method; Oxidation stability in accordance with the Rancimat method; Iodine value; Peroxide value; Saponification value; Acid value, free fatty acids (FFA); Hydroxyl number; Traces of nickel using polarography; Special care is taken to avoid chlorinated solvents in these methods. Also, as many of the mentioned methods as possible are automated.

This Application Bulletin describes the determination of water in non-explosive and non-flammable gaseous samples using the coulometric Karl Fischer method. This method is ideal for very low water contents.

The bromine number and bromine index are important quality control parameters for the determination of aliphatic C=Cdouble bonds in petroleum products. Both indices provide information on the content of substances that react withbromine. The difference between the two indices is that the bromine number indicates the consumption of bromine in gfor 100 g sample and the bromine index in mg for 100 g sample.This Application Bulletin describes the determination of the bromine number according to ASTM D1159, ISO 3839, BS2000-130, IP 130, GB/T 11135 and DIN-51774-1. The bromine index determination for aliphatic hydrocarbons is described according to ASTM D2710, IP 299, GB/T 11136 and DIN 51774-2. For aromatic hydrocarbons the determination of the bromine index is described according to ASTM D5776 and SH/T 1767. UOP 304 is not recommended for the determination of the bromine number or bromine index because its titration solvent contains mercuric chloride.

The determination of the physical and chemical parameters as electrical conductivity, pH value, p and m value (alkalinity), chloride content, the calcium and magnesium hardness, the total hardness, as well as fluoride content are necessary for evaluating the water quality. This bulletin describes how to determine the above mentioned parameters in a single analytical run.Further important parameters in water analysis are the permanganate index (PMI) and the chemical oxygen deman (COD). Therefore, this Bulletin additionally describes the fully automated determination of the PMI according to EN ISO 8467 as well as the determination of the COD according to DIN 38409-44.

This Bulletin, using practical examples, indicates how the user can achieve optimum pH measurements. As this Bulletin is intended for actual practice, the fundamentals - which can be found in numerous books and publications - are treated only briefly.

Only coulometric Karl Fischer titration can determine low water contents with sufficient accuracy.This Application Bulletin describes the direct determination according to ASTM D6304, ASTM E1064, ASTM D1533, ASTM D3401, ASTM D4928, EN IEC 60814, EN ISO 12937, ISO 10337, DIN 51777, and GB/T 11146. The oven technique is described according to ASTM D6304, EN IEC 60814, and DIN 51777.

Generally speaking, the gas extraction or oven method can be used for all samples which release their water when they are heated up. The oven method is indispensable in cases in which the direct volumetric or coulometric Karl Fischer titration is not possible, either because the sample contains disruptive components or because the consistency of the sample makes it very difficult or even impossible to transfer it into the titration vessel.The present Application Bulletin describes automatic water content determination with the aid of the oven technique and coulometric KF titration, using samples from the food, plastic, pharmaceutical and petrochemical industry.

The presented titration system can be used for the fully automated determination of the hydroxyl number (HN) according to ASTM E1899 and EN ISO 4629-2. The method allows, the determination of polyols and oxooils without boiling under reflux or other sample preparation and is therefore a big benefit for laboratories that have to cope with a high sample throughput.The standards EN 15168 and DIN 53240-3 relay on the same analysis method as in ASTM E1899.

This bulletin describes a procedure to determine the bromine index (BI) using coulometric titration. The bromine index is the fraction of reactive unsaturated compounds (mostly C=C double bonds) in hydrocarbons encountered in the petrochemical industry. The double bonds are split with the attachment addition of bromine.

The determination of the acid number plays a significant role in the analysis of petroleum products. This is manifested in the numerous standard procedures in use over the world (internal specifications of multinational companies, national and international specifications of ASTM, DIN, IP, ISO, etc.). These procedures differ mainly in the composition of the used solvents and titrants.This bulletin describes the determination of the acid number in petroleum products by applying different types of titration.The potentiometric determination is described according to ASTM D664, the photometric according to ASTM D974 and the thermometric titration according to ASTM D8045.

This Application Bulletin shows the determination of the total base number in petroleum products by applying different titration types according to various standards.

MATi 4 (Metrohm Automated Titration) is a configured system for automated water content determination in liquid samples using coulometric Karl Fischer titration. The maximum sample volume is 5 mL. Up to 160 samples are filled in glass vials and sealed with lids. This ensures that the water content in the samples remains constant. The samples are aspirated and transferred into the coulometric cell through a needle. The tiamo™ software controls the system.

This Application contains information regarding titer determination in Karl Fischer titration, in particular regarding the water standard suitable for a titer determination and for the correct handling of the same.Titer determination for Karl Fischer titrants is indispensable, because the titer is subject to changes caused by the humidity in the air. The frequency of the determination depends on the titrant and the tightness of the system.The titer has the unit mg/mL in Karl Fischer titration. The value calculated in a titer determination indicates how many milligrams of water react on one milliliter of titrant.

This Application Bulletin describes the determination of the total acid number in various oil samples by catalytic thermometric titration as per ASTM D8045.

Determination of traces of lithium, sodium, ammonium, potassium, calcium, and magnesium in ethanol using cation chromatography with direct conductivity detection after Metrohm Inline Matrix Elimination.

Determination of traces of lutetium, ytterbium, thulium, erbium, terbium, gadolinium, samarium, neodymium, praseodymium, cerium, and lanthanum using cation chromatography with direct conductivity detection.

Determination of potassium, magnesium, and calcium in biodiesel using cation chromatography with direct conductivity detection applying automated extraction and subsequent Metrohm Inline Dialysis.

Determination of traces of lutetium, ytterbium, thulium, erbium, terbium, gadolinium, samarium, neodymium, praseodymium, cerium, and lanthanum using cation chromatography with gradient elution and UV/VIS detection after post-column reaction with Arsenazo III.

Determination of lithium, sodium, ammonium, potassium, manganese, calcium, magnesium, strontium, and barium in an offshore effluent using cation chromatography with direct conductivity detection.

In natural gas production, the removal of contaminants, and in particular acidic gases such as H2S and CO2, is exceptionally important. These acidic gases are removed in the amine wash through chemical treatment with amines or alkanol amines. This application shows a convenient and precise analysis with the separation of various amines and standard cations on a column of the Metrosep C 6 - 250/4.0 type with subsequent direct conductivity detection.

N-methyldiethanolamine and piperazine are used in scrubber solutions, e.g., in the natural gas process. Testing this type of samples by ion chromatography requires a good resolution and the separation of amines from standard cations. The separation is achieved on a Metrosep C 4 - 150/4.0 column applying direct conductivity detection.

Before the liquefaction process of the natural gas, carbonate and hydrogen sulfide need to be removed through a scrubber solution containing piperazine and N-methyl diethanolamine (MDEA). The concentration ratio of the two components is determined by ion chromatography on a Metrosep C 4 - 150/4.0 column applying direct conductivity detection.

Abrasive machining of e.g., metal parts requires a cooling lubricant. Their purpose besides cooling and lubrication is to inhibit corrosion. Amines are added to the emulsion to keep the pH high. In the actual application, DCHA and MDCHA have to be analyzed besides other amine components and inorganic cations. To avoid oil contamination on the IC system, Inline Dialysis is applied. The detection is performed by direct conductivity detection.

Bicine (2-(Bis(2-hydroxyethyl)amino)acetic acid) is a corrosive component. It has to be avoided in acidic gas sweetening solvents. These solvents are based on organic amines. Bicine is amphoteric, holding a carboxylic and an amine group. Under the applied conditions, the amine groups are at least partially protonated and therefore may be separated by cation chromatography. The detection mode is direct conductivity detection.

Natural liquefied petroleum gas (LPG) is a mixture of hydrocarbon gases (e.g. propane and butane), but it also contains acidic contaminants (e.g. carbon dioxide or hydrogen sulfide). These gases need to be scrubbed from the petroleum gas as they are highly corrosive. This purification step, referred to as «sweetening», is often performed by using alkaline amine solutions. Thereby the amine solution absorbs the acidic gases, while the raw LPG is neutralized. To guarantee that amine residues in the sweetened gas do not influence the gas quality, the amines in the final LPG are determined by scrubbing the gas with acetic acid as described in UOP 936-96. The recent method enables the quantification of the amines dimethylamine (DMA), diethylamine (DEA), dipropylamine (DPA), and dibutylamine (DBA) by separation from standard cations.

Isopropylamine and dicyclohexylamine are used as emulsifiers and need to be determined in emulsions along with standard cations. However, emulsions must not be injected directly into the ion chromatograph as the organic components may damage the ion exchanger stationary phase in the separation column. Inline Dialysis as sample preparation is the perfect tool for such samples. The ions of interest are separated from the organic phase by diffusion through the hydrophilic membrane, thus protecting the column. Full automation makes the analyses even easier and more efficient for the user.

Harmful industrial flue gases like H2S and CO2 cause corrosion of pipes and damage the environment. Adding the correct amount of amines in scrubber solutions, e.g. ethanolamines and methylamines, will neutralize these gases («gas sweetening»). Non-suppressed cation analysis with direct conductivity detection is a straightforward and robust technique for the quantification of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA) via ion chromatography. Thanks to the high capacity of the Metrosep C 6 column, large volumes can be injected without compromising the peak shapes. The analytical technique can be used at laboratory scale but also for process analysis.

Determination of chloride and sulfate (non-quantified) in a high-viscosity oil sample using combustion digestion and subsequent anion chromatography with conductivity detection following sequential suppression.Keyword: pyrohydrolysis

This Application Note looks at the determination of fluorine and sulfur in certified liquefied gas using Metrohm Combustion IC. Sequential determinations proceed in parallel to a certain extent: While the absorption solution of a sample that has already been combusted is being analyzed with IC, the combustion of the next sample is already underway.Keyword: pyrohydrolysis

Paraffin and lubricating oils are yielded from the wax fraction of raw oil distillation. The chloride content of both should be low. This Application Note describes chloride determination after inline combustion. Although it does not happen in this application, this method can also be used to quantify the sulfur content.Keyword: pyrohydrolysis

This Note addresses the determination of the fluorine and chlorine content of a liquefied gas sample (LPG, Liquid Petroleum Gas), i.e. halogens in a mixture of propane and butane. Fluorine originates from perfluorobutane and chlorine from methyl chloride. LPG/GSS modules are used to introduce 50 µL of sample into the combustion system. The halogens released during combustion are determined using ion chromatography with intelligent partial loop injection technique following Inline Matrix Elimination.Keyword: pyrohydrolysis

Palm oil is a vegetable oil that is used not only in the food industry but also for the manufacture of soaps and body care products. It is furthermore an important raw material for the generation of biodiesel. Depending on the degree of refinement, palm oil can be red, reddish or even colorless in appearance. The carotenes responsible for the color are removed during refinement and the oil becomes increasingly clear. In this Note, the chlorine and sulfur content of various palm oils are determined using Combustion IC.Keyword: pyrohydrolysis

ASTM D7994 - 17 describes the determination of fluorine, chlorine, and sulfur in liquefied petroleum gas (LPG) by oxidative pyrohydrolytic combustion followed by ion chromatography. A synthetic butane sample is analyzed. 50 µL of the sample is injected into the combustion system using the LPG Module. The combustion products are analyzed by IC applying intelligent Partial Loop Injection Technique after Inline Matrix Elimination.

The content of organic chloride in crude oil is determined according to ASTM D8150 in the naphtha fraction after distillation. The naphtha fraction is washed with caustic and water, respectively, to remove hydrogen sulfide and inorganic halides. Here, the determination of organic chloride after inline combustion is presented. Although the sulfur content was of no interest in this application, the same setup allows sulfur quantification.

Crude oil typically contains no organic halides. These are introduced at production sites, in pipelines, or in storage tanks. These components produce HF, HCl, and other acids in reforming and hydro-treating processes, leading to corrosion and catalyst poisoning. Speciation of the halides is an important parameter to measure in order to trace the contamination source. The current specifications expect to find less than 2 mg/kg organic chlorine in crude oil. Sulfur in crude oil could be quantified on the fly. Due to the specific request in this application, only the halogens are determined.

Sulfur species are critical contaminants in ammonia gas. They can cause high-temperature sulfidation of metals, form aggressive complexes with other elements, or react subsequently in processes where the ammonia gas is used. The concentration of such impurities tends to be very low, but they may not exceed critical levels of 0.5 mg/L. Although this level is very close to the system blank of the Combustion IC system, the setup can be used to prove that such critical limits are not exceeded.

Corrosion refers to a process that involves deterioration or degradation of metal. The most common example of corrosion is the formation of rust on steel. Most corrosion phenomena are of electrochemical nature and consist of at least two reactions on the surface of the corroding metal.

Electrochemical methods provide an alternative to traditional methods used to determine the rate of corrosion. For example, corrosion rates, the rates at which a specimen corrodes, can be calculated from simple electrochemical measurements like a linear sweep voltammetry (LSV).

Polarization resistance (Rp) can quantify the corrosion resistance of metals as an alternative to Tafel analysis. Its methodology and practical use as described in ASTM G59 are discussed.

Electrochemical impedance spectroscopy or EIS has been used effectively to measure the polarization resistance for corrosion systems and for the determination of corrosion mechanisms.

A corrosion inhibitor is a substance that reduces the corrosion rate of a metal. A corrosion inhibitor is usually added in a small concentration to the corrosive environment. This application note shows how Metrohm Autolab instruments can be used to check the quality of inhibitors.

This Application Note is based on the ASTM standard G150, developed to test the resistance of stainless steel, and otheralloys related to stainless steel, on pitting formation at elevated temperature. This is achieved by determining the potential-independent critical pitting temperature (CPT), defined as the lowest temperature at which pitting evolution occurs. The CPT experiment consists of applying a potential to the specimen while the cell temperature is raised and recording the current.

In this Application Note, stepwise dissolution measurement (SDM) is applied to aluminum samples coated with different materials, in order to gain insights in corrosion protection. The combination of the Autolab PGSTAT204 with the 1 L Autolab corrosion cell and the NOVA software provides the suitable setup to perform SDM and other corrosion experiments.

In this Application Note, EIS is applied on three coated aluminium samples, before and after the stepwise dissolution measurement (SDM). This technique has been reviewed in the Application Note AN-COR-08.

Corrosion of metals is a problem seriously affecting not only many industrial sectors, but also private life, resulting in enormous costs. In this application note, the results gained during electrochemical corrosion studies on different metals are compared to literature data.

The ASTM standard G100 is an electrochemical method to test localized corrosion of aluminum 3003-H14 and other alloys. A cyclic galvanostatic staircase polarization (galvanostaircase) is composed of an upward and a downward scan. The potential values at the end of each step are collected and linearly fitted, and the potential values at zero current are found.

This Application Note evaluates corrosion in Type 430 stainless steel according to ASTM G5 with VIONIC powered by INTELLO and an ASTM-compliant corrosion cell setup.

The rotating cylinder electrode (RCE) is a technique used in corrosion research to simulate in a laboratory environment the turbulent flow which usually occurs when liquids are transported through pipelines. The RCE is used to generate a turbulent flow at the surface of a sample, simulating the pipe flow conditions. Experiments that involve an RCE are regulated by the ASTM G185 standard. In this application note, The RCE with a 1018 carbon steel cylinder sample was used with the linear polarization (LP) measurement technique.

The rotating cylinder electrode (RCE) is successfully used in a laboratory environment to generate a turbulent flow at the surface of a sample, simulating realistic pipe flow conditions. In this application note, the corrosion rate is measured and compared between quiescent and turbulent flow conditions, while keeping all the other experimental conditions unchanged. The linear polarization (LP) technique was used together with the RCE (with and without rotation).

This Application Note details ASTM G61-compliant corrosion measurements performed with VIONIC powered by INTELLO using Metrohm’s ASTM-compliant corrosion cells.

Tafel analysis is an important electrochemical technique used to understand reaction kinetics. By studying the Tafel slope, it reveals the rate-determining steps in electrode reactions, aiding fields like corrosion and fuel cell research. This method helps industries optimize processes and improve device performance by tailoring materials and conditions for greater efficiency.

The Metrosep C Supp 2 column family is polystyrene/divinylbenzene based and therefore sequential cation suppression may be applied. This AN shows the separation and detection of different amines on the 150 mm version of the column with subsequent conductivity detection after sequential cation suppression.

A reference electrode has a stable and well-defined electrochemical potential (at constant temperature), against which the applied or measured potentials in an electrochemical cell are referred. A good reference electrode is therefore stable and non-polarizable. In other words, the potential of such an electrode will remain stable in the used environment and also upon the passage of a small current. This application note lists the most used reference electrodes, together with their range of use.

The determination of heavy metal ions in a solution is one of the most successful application of electrochemistry. In this application note, anodic stripping voltammetry is used to measure the presence of two analytes, in a sample of tap water.

In this Application Note, hydrogen permeation experiments are conducted following the procedure described in the ASTM standard G148.

The Devanathan-Stachurski cell (or «H cell») is successfully used to evaluate the permeation of hydrogen through sheets or membranes. As small amounts of hydrogen pass through the sheet or membrane, a very sensitive potentiostat is required for its detection. A study of the hydrogen permeation properties of different iron sheets is discussed in this Application Note while taking the instrumental requirements into account.

Electrochemical impedance spectroscopy (EIS) is a widely used multidisciplinary technique for characterizing the behavior of complex electrochemical systems. EIS is employed in the study of a range of complex systems including batteries, catalysis, and corrosion processes. This Application Note focuses on the basic principles of EIS measurements.

A typical electrochemical impedance spectroscopy (EIS) experimental setup consists of an electrochemical cell, a potentiostat/galvanostat, and a frequency response analyzer (FRA). This Application Note introduces common EIS experimental setups as well as details of the main experimental parameters.

Explore how to construct simple and complex equivalent circuit models for fitting EIS data in this Application Note. Nyquist plots are shown for each example.

In the application note AN-EIS-004 on equivalent circuit models, an overview of the different circuit elements that are used to build an equivalent circuit model was given. After identifying a suitable model for the system under investigation, the next step in the data analysis is estimation of the model parameters. This is done by the non-linear regression of the model to the data. Most impedance systems come with a data-fitting program. In this application note, the way NOVA is uses to fit the data is shown.

In this application note, the advantage of recording the raw time domain data for each individual frequency during an electrochemical impedance measurement is described.

Electrochemical impedance spectroscopy (EIS) is a powerful technique which provides information about the processes occurring at the electrode-electrolyte interface. The data collected with EIS are modeled with a suitable electrical equivalent circuit. The fitting procedure will change the values of the parameters until the mathematical function matches the experimental data within a certain margin of error. In this Application Note, some suggestions are given in order to get acceptable initial parameters and to perform an accurate fitting.

Determination of Total Acid Number (TAN) values in mineral oils and similar fluids.

Thermometric titration quickly and accurately assesses the total solids content of fluids employed in drilling oil and gas wells within minutes.

Thermometric titration is presented as a simple, fast, and reliable method to determine calcium content in various drilling fluids.

Determination of ferrous ions in heat exchanger and vessel acid wash solutions, for measuring the effectiveness of acid inhibitors used in the solutions. Depending on the condition of the sample, the lower practical limit for the determination will vary from approximately 20-100mg/Kg Fe2+. Samples with high silicic acid contents require relatively large amounts of dilution water to render them mobile, and this limits the aliquot size and hence the amount of Fe2+ which can be analyzed.

Determination of chloride in oil well drilling fluids.

Determination of moisture in lubricating oils with TEOF (triethyl orthoformate).

Determination of tar acids in coal tar products. This procedure may also be applied to the determination of a range of weakly acidic organic compounds such as carboxylic acids, hydroxy acids, phenols, phenolic acids, keto-enols, imides, and aromatic nitro compounds.11 Vaughan, G. A. Thermometric and Enthalpimetric Titrimetry. Van Nostrand Reinhold Co. Ltd (1973)

Determination of water in automotive lubricating oils.

Determination of low content of HCl (around 10 ppm) in silicone oil.

The determination of the total base number (TBN) in motor oils is accomplished by means of titration with a standard solution made up of trifluoromethanesulfonic acid in glacial acetic acid and isobutyl vinyl ether as reagent for improved end point identification.

Determination of Total Acid Number (TAN) values in biodiesel to <0.05 mg KOH/g sample.

Determination of free acid in sulfuric acid («acid shot») solutions employed in the removal of silicate scale in heat exchangers. This method is suitable for acid shot solutions where the silicic acid content is so high that the solutions have gelled.

Automated determination of total acid number (TAN) in new and used lubricating oils and crude oils using the 814 USB Sample Processor. Dissolve oil sample in mixture of toluene and 2-propanol, add paraformaldehyde and titrate with 0.1 mol/L or 0.01 mol/L KOH in propan-2-ol. The endpoint is indicated by an endothermic response caused by the base-catalyzed depolymerization of paraformaldehyde.Reference: 1. M. J. D. Carneiro, M. A. Feres Júnior, and O. E. S. Godinho. Determination of the acidity of oils using paraformaldehyde as a thermometric end-point indicator. J. Braz. Chem. Soc. 13 (5) 692-694 (2002)

Dissolution of oil in toluene, and titration with standard 0.1 mol/L trifluoromethanesulfonic acid in acetic acid using isobutyl vinyl ether as a thermometric endpoint indicator.

Thermometric titration can determine the total acid number (TAN) of various crude oil products according to ASTM D8045 without requiring any sensor maintenance.

The water content of turbine oil is determined according to Karl Fischer. Because of the low water content of the sample, coulometric titration is used.

The water content of diesel fuel and petrol (gasoline) is determined according to Karl Fischer. Because of the low water content, the determinations are carried out by coulometric titration.

The water content of used lubricating oil is determined according to Karl Fischer by coulometric titration. To prevent unwanted side reactions special KF reagents are used.

The water content of silicone oil is determined according to Karl Fischer by coulometric titration.

This Application Note describes the determination of the water content in transformer oil using the oven technique.

The bromine index indicates the degree of unsaturation and relies on the simple addition of bromine to the double bond of alkenes. One mole of bromine is consumed for each mol of carbon-carbon double bond. The bromine index indicates the olefin content in aromatic hydrocarbons. This Application Note describes the determination by coulometric titration according to ASTM D1492.

The water content determination by volumetric Karl Fischer titration is one of the most important analyses worldwide. Using an OMNIS system consisting of an OMNIS Titrator and an OMNIS Sample Robot, the fully automatic analysis of water content is possible in various products and matrices. The OMNIS Sample Robot is capable of running several different titrations in parallel. In this Application Note, we present the results of a volumetric Karl Fischer titration run in parallel to an aqueous acid-base titration on the same system. The water content is not influenced by the parallel running aqueous titration, allowing the combination of potentiometric titrations and Karl Fischer titrations on the same automated system.

Moisture in petroleum products causes several issues: corrosion and wear in pipelines and storage tanks, an increase in debris load resulting in diminished lubrication, blocked filters, or even harmful bacterial growth. As a result, increased water content can lead to infrastructure damage, higher maintenance costs, or even unwanted downtimes.Coulometric Karl Fischer titration is the method of choice for low water content in petroleum products. Using a Karl Fischer oven to vaporize the water present in the sample prior to titration not only greatly reduces matrix interferences, it can also be fully automated. This allows a reliable and cost-efficient analysis of the water content according to ASTM D6304 (Procedure B) in products such as diesel, hydraulic oil, lubricant, additive, turbine oil, and base oil.

Karl Fischer reagents contain buffer substances (usually imidazole) since the reaction constant is dependent on the pH value. A constant pH therefore ensures the most repeatable results. In 2015, imidazole was classified by European Union the as a CMR (carcinogenic, mutagenic or toxic) substance and the statement H360D was added, stating possible harm to fertility or a fetus. Meanwhile, other reagents free of imidazole are available for purchase. This Application Note summarizes test measurements with 34433 HYDRANAL™ NEXTGEN Coulomat AG-FI.

To determine water in crude oil, ASTM D4928 recommends coulometric Karl Fischer titration with the oven method, allowing full automation for high reproducibility.

Determination of acetic, propionic, butyric, valeric, and caproic acid in produced water using anion chromatography with conductivity and MS detection after post-column addition of ammonia for MS detection and inline sample preparation by dialysis.

Determination of phosphate in produced water containing up to 100 g/L chloride as well as crude oil using anion chromatography with conductivity and MS detection after inline dialysis.

Determination of diethylamine and trimethylamine using cation chromatography with MS detection.

In recent years, there has been a significant push to reduce the environmental impacts of fuels through improvements to fuel quality. The determination of key quality parameters of gasoline, namely research octane number (RON, ASTM D2699-19), motor octane number (MON, ASTM D2700-19), anti knock index (AKI), aromatic content (ASTM D5769-15), and density, conventionally requires several different analytical methods, which are laborious and need trained personnel. This application note demonstrates that the XDS RapidLiquid Analyzer, operating in the visible and near-infrared spectral region (Vis-NIR), provides a cost-efficient and fast solution for the multiparameter analysis of gasoline.

Pyrolysis gasoline (Pygas) is a by-product of ethylene production, which contains unwanted conjugated diolefins making it unsuitable as a motor fuel. To overcome this limitation, the olefin content needs to be reduced below 2 mg/g pygas in a selective hydrogenation unit (SHU). The diene value, or maleic anhydride value (MAV), is usually determined by the lengthy Diels-Alder wet chemical method (UOP326-17), requiring highly trained analysts. In contrast to the primary method, near-infrared spectroscopy (NIRS) is a cost-efficient and fast analytic solution for the determination of diene value in pyrolysis gasoline.

This Application Note describes the determination of various indices (mainly with ASTM and ISO conformance) for the characterization of kerosene as aviation turbine fuel using near-infrared spectroscopy. The following parameters were determined with the aid of an NIRS XDS Process Analyzer: degree of density in accordance with the American Petroleum Institute (API), aromatics content, Cetane Index, distillation characteristics pursuant to ASTM D86, flash point, freezing point, viscosity and hydrogen content. All of these parameters are determined quickly and easily with just a single measurement.

For lubricant analysis, determination of the Acid Number (ASTM D664), viscosity (ASTM D445), moisture content (ASTM D6304), and color number (ASTM D1500) require the use of multiple analytical technologies and, in part, large volumes of chemicals. This application note demonstrates that the XDS RapidLiquid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) provides a fast and cost-efficient alternative for the determination of the AN, viscosity, moisture content, and color number of lubricants. With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows for multi parameter analysis of lubricants in less than one minute.

This Application Note demonstrates the data transfer from a Fourier transform to a dispersive NIR instrument, using quality control of lubricating oils as an example application. It is shown that FT-NIR instruments can be replaced by dispersive ones without time-consuming sample remeasurement and subsequent method development.

This Application Note shows that visible near-infrared spectroscopy (Vis-NIRS) can determine water content in ethanol-hydrocarbon blends. Vis-NIRS is a fast alternative to conventional lab methods: it accelerates raw material inspection, process monitoring, and final product control.

Acid Number (AN) analysis of lubricants (ASTM D664) can be a lengthy and costly process due to usage of large amounts of chemicals and required cleaning steps of the analytical equipment between each measurement. This application note demonstrates that the XDS RapidLiquid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) provides a cost-efficient, fast alternative for the determination of the acid number of lubricants. With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows for the analysis of AN in less than a minute.

The cetane index (ASTM D613), flash point (ASTM D56), cold filter plug point (CFPP) (ASTM D6371), D95 (ISO 3405), and viscosity at 40°C (ISO 3104) are key parameters to determine for diesel quality. The primary test methods are labor intensive and challenging due to the need to use different analytical methods. This application note demonstrates that the NIRS XDS RapidLiquid Analyzer provides a cost-efficient and fast solution (under 1 minute) for the simultaneous determination of these key parameters in diesel.

The quality control of diesel exhaust fluids (DEF) is key to ensure the optimal catalytic performance and prevent damage to the exhaust system in diesel vehicles. The standard method to determine urea content is measuring the refractive index (ISO 22241-2:2019). The issue is that although this method is fast, it is not as accurate as other methods (e.g., HPLC). This application note demonstrates that the DS2500 Liquid Analyzer provides a fast solution with high accuracy for the determination of urea in DEF. With no sample preparation or chemicals needed, visible near infrared (Vis-NIR) spectroscopy allows for the analysis of diesel exhaust fluids in less than a minute.

The production of biofuels from renewable feedstock has grown immensely in the past several years. Bioethanol is one of the most interesting alternatives for fossil fuels, since it can be produced from raw materials rich in sugars and starch. Ethanol fermentation is one of the oldest and most important fermentation processes used in the biotechnology industry. Although the process is well-known, there is a great potential for its improvement and a proportional reduction in production costs. Due to the seasonal variation of feedstock quality, ethanol producers to need to monitor the fermentation process to ensure the same quality product is achieved. Near-infrared spectroscopy (NIRS) offers rapid and reliable prediction of ethanol content, sugars, Brix, lactic acid, pH, and total solids at any stage of the fermentation process.

This application note presents near-infrared spectroscopy (NIRS) as an alternative for bromine number determination in pyrolysis gasoline.

This Application Note highlights near-infrared spectroscopy as a faster, cost-effective alternative to KF titration for predicting water content in diesel fuel.

Alkaline additives in engine lubricants are used to prevent the build-up of acids and as a result, they inhibit corrosion. The total base number (TBN) indicates the amount of basic additives present in samples and thus can be used as a measure for the degradation of the lubricant. The standard test method for TBN in lubricants is potentiometric titration according to ASTM D2896. This method requires the use of toxic reagents involves a labor-intensive cleaning procedure. In contrast to the primary method, near-infrared spectroscopy (NIRS) is a fast analytical technique which does not produce any chemical waste and completes the TBN analysis in less than one minute.

The standard method to determine RON in isomerate is with expensive and maintenance-intensive engines. In contrast to this, the research octane number can also be analyzed by near-infrared spectroscopy (NIRS). NIRS provides accurate results within one minute without the need for any sample preparation or chemicals.

The determination of key quality parameters of reformate—namely research octane number (RON, ASTM D2699-19), aromatic content (ASTM D5769-15), benzene content, olefin content, and density—requires time-consuming and laborious conventional methods. In contrast, the Metrohm DS2500 Liquid Analyzer can measure all of these parameters, providing results within one minute without any sample preparation.

Determination of the biodiesel content in diesel with NIR spectroscopy is fast and requires no sample preparation nor chemicals, reducing workload and costs.

Determination of glycolic acid, formic acid, acetic acid and carbonic acid in a scrubber solution using ion-exclusion chromatography with conductivity detection after chemical suppression.

Determination of acetate and formate in an amine solution using anion chromatography with conductivity detection after suppression.

Determination of formate, acetate, propionate, isobutyrate, butyrate, isovaleriate, valeriate, and capronate using ion-exclusion chromatography with suppressed conductivity detection after inline dialysis.

Monoethylene glycol (MEG) is used to remove water from natural gas before further processing. Due to high temperatures applied, glycol degradation to glycolic, formic, and acetic acid may occur. These reactions are unwanted as the emerging acids are corrosive. The determination of the organic acids is achieved by ion-exclusion chromatography with conductivity detection after inverse suppression.

Acidic gas sweetening solvents are used to remove acid gases such as H2S and CO2 from streams. Typically, amines are applied as alkaline components in these solvents. The determination of organic acids (glycolic, acetic, formic, propionic, and butyric acid) is achieved by ion-exclusion chromatography with conductivity detection after inverse suppression.

Sulfide and cyanide are toxic anions. Their trace determination in any kind of water samples, especially in wastewater, is requied for safety reasons. However, metal traces present in the eluent can mask target anions due to complexation. The addition of a stronger complexing agent to the eluent mask these metal cations enabling interference free determaination. This application is mainly used for the analysis of cyanide and/or sulfide in water. However, it also fulfills the requirements of ASTM D2036 for the determination of total, amenable, weak acid dissociable cyanides. The determination of cyanide and sulfide require an alkaline eluent and amperometric detection. This Application Note describes a new column/eluent combination for optimized separation. The combination consists of the Metrosep A Supp 10 - 100/4.0 column and a sodium hydroxide eluent containing a trace of EDTA for transition metal complexation. This yields in better peak shape and detection limits below 0.1 μg/L.

Biodiesel or green diesel is manufactured from fats and vegetable oils through ester interchange of the triglycerides they contain, during which glycerin accumulates as byproducts in both free and bonded forms. These accelerate fuel ageing and lead to deposits and clogged filters, which is why maximum permissible highest concentrations have been established (in the US in ASTM D6751 and in the EU in EN 14214).The two specifications prescribe the ion chromatography determination of free and bonded glycerin. This Note describes the determination with the aid of the Metrosep Carb 2 - 150/4.0 column in accordance with ASTM D7591.

This Process Application Note details the simultaneous online analysis of H2S and NH3 in sour water which was previously treated in the sour water stripper (SWS). The method includes automatic cleaning and calibration. Fast and accurate results are continuously supplied for process control.

Carbon capture systems strip carbon dioxide from flue gases. Online analysis of amines and carbon dioxide enhances amine usage efficiency and reduces operational costs.

Automated online analysis with the 2060 TI Ex Proof Process Analyzer facilitates constant monitoring of the crude oil desalting process according to ASTM D3230.

Online mercaptan and H₂S monitoring with the 2060 TI Ex Proof Analyzer certified for Zone-1 and Zone-2 areas.

Reliable monitoring of TBC in styrene according to ASTM D4590 requires an explosion-proof solution like the 2060 TI Ex Proof Analyzer.

Online acid number analysis in various oil products is possible with thermometric catalytic titration according to ASTM D8045 using the 2060 TI Ex Proof Process Analyzer.

A safer way to monitor moisture content in crude distillation unit overhead fractions is with inline near-infrared spectroscopy using the 2060 The NIR-Ex Analyzer.

In refineries, high octane products are desired since they are used to produce premium gasoline. Catalytic reforming converts heavy naphtha into a high octane liquid product called reformate (a mixture of aromatics and iso-paraffins C7 to C10). The reformate must be constantly monitored to ensure high throughput along the refining process. Traditionally, the octane numbers can be measured by two different methodologies: Inferred Octane Models (IOM) and laboratory octane engine analysis. However, these do not provide «real-time» results and require constant maintenance and human intervention to adapt to current operation conditions. «Real-time» analysis of the octane number in fuels can be performed online via near-infrared spectroscopy (NIRS) technology, which fits well within the international standards (ASTM). Utilization of a Metrohm Process Analytics NIRS XDS Process Analyzer (ATEX version) in conjunction with a sample preconditioning system makes analysis of the octane number simple, fast, and reliable, allowing quick adjustments to the process for a better quality product and higher profitability.

Many fermentation quality parameters can be monitored simultaneously directly in the tank with inline near-infrared spectroscopy, such as the 2060 The NIR Analyzer.

In this Application Note, the 893 Professional Biodiesel Rancimat measures the oxidation stability of biodiesel (or fatty acid methyl esters, FAME), an eco-friendly fuel.

The oxidation stability of biodegradable lubricating oil is determined using the Rancimat method.

Motor oils are exposed to high shear forces and temperatures while the motor is running. Mechanical abrasions set iron and copper free, which act as catalysts for oxidation. All of this decreases the durability of motor oils. The oxidation stability with iron and copper catalysts can give an approximate indication for the shelf life. A reproducible and accurate determination of the oxidation stability using the 892 Professional Rancimat can be realized.

Sustainable biodiesel can be blended with petroleum diesel. The 893 Professional Biodiesel Rancimat measures the oxidation stability of biodiesel and its blends.

Mercaptans in fuels are corrosive and regulated at trace levels. SERS enhances Raman signals to enable their accurate detection and quantification below standard LODs.

Determination of chloride, nitrite, nitrate, phosphate, and sulfate in cutting oil emulsion using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

Determination of sulfate in diesel engine coolant using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

Determination of chloride, nitrite, bromide, nitrate, phosphate, and sulfate in Schoeniger absorption solution using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride, bromide, nitrate, sulfite, sulfate, phosphate, oxalate, thiosulfate, and thiocyanate (heat stable salts) in scrubber solutions using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride, nitrite, nitrate, and sulfate in cooling lubricants using anion chromatography with conductivity and UV detection (230 nm) after chemical suppression and inline sample preparation by dialysis.

Determination of fluoride, acetate, formate, and chloride in gasoline using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, acetate, formate, and chloride in a brake fluid using anion chromatography with conductivity detection after chemical suppression.

Determination of sulfate in an ethanol sample used as an additive for gasoline using anion chromatography with conductivity detection after chemical suppression.

Determination of glycolate, formate, chloride, nitrite, nitrate, phosphate, sulfate, and oxalate in engine coolant using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride and sulfate in ethanol using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, acetate, formate, nitrate, and sulfate in a gasoline/bioethanol mixture (85% gasoline, 15% ethanol) using anion chromatography with conductivity detection after sequential suppression and Metrohm Inline Matrix Elimination.

Determination of fluoride, acetate, propionate, formate, butyrate, chloride, nitrite, bromide, nitrate, benzoate, phosphate, sulfate, malonate, and oxalate in an industrial process water using anion chromatography with conductivity detection after sequential suppression.

Determination of chloride, nitrate, and sulfate in produced water using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, acetate, formate, chloride, nitrite, nitrate, phosphate and sulfate in an E85 mixture (85% ethanol and 15% gasoline) by means of anion chromatography with conductivity detection and sequential suppression. The Inline Matrix Elimination serves as sample preparation.

Determination of fluoride, chloride, bromide, and iodide in petroleum coke after microwave combustion using anion chromatography with conductivity detection after sequential suppression.

Determination of chloride, nitrite, bromide, nitrate, phosphate, sulfite, sulfate, and oxalate in a cooling lubricant using anion chromatography with conductivity detection and subsequent UV detection (see AN-U-047) after sequential suppression and Metrohm Inline Dialysis.

Determination of acetate, chloride, nitrite, bromide, nitrate, phosphate, sulfate, oxalate, fumarate, and molybdate using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, formate, chloride, nitrite, bromide, nitrate, sulfate, oxalate, and molybdate in a coolant using anion chromatography with conductivity detection after chemical suppression and Metrohm Inline Dialysis.

Hydrogen sulfide (H2S) and carbon dioxide (CO2) are disruptive byproducts of natural gas that must be eliminated during conveyance. This is accomplished with the aid of gas scrubbing, during which the gas flow is cleaned with absorbers such as alkanolamines or akylalkanolamines (e.g., methyldiethanolamine, MDEA). Reliable analysis is imperative, given that heat-stable salts often accumulate in the absorber and thus inhibit the absorption capacity for acid gases.The determination of heat-stable salts (SCN–, S2O32–, SO32–, SO42–, etc.) in MDEA solutions takes place on the Metrosep A Supp 5 - 250/4.0 column with conductivity detection following sequential suppression.Key words: amine gas treating, scrubber

Monoethylene glycol is used for dehydration of the natural gas before liquefaction and has to be checked for its purity on routine basis. Inorganic anions and their corresponding acids are corrosive. Therefore, they have to be kept at minimum level. The separation is performed on a microbore Metrosep A Supp 16 - 250/2.0 column and quantified by conductivity detection after sequential suppression.

«High ionic water» is typically water containing a high concentration of chloride (e.g. seawater, brine), but this also describes water samples resulting from petrochemical processes. Due to the high chloride concentrations, the conductivity determination of minor ionic components is limited. Thus, minor anions like nitrite, bromide, and nitrate can elute under or on the tail of the large chloride peak, and their detection in low concentrations is hampered. However, combining conductivity and UV/VIS detection as described in ASTM D8234 enables the determination of anions that are UV active. Chloride does not interfere in this situation. The described technique enables the interference-free simultaneous determination of trace anions besides high chloride content.

ASTM D8234 describes the determination of anions in high saline water by applying suppressed conductivity followed by UV/VIS detection. This combination enables the determination of e.g. nitrite by UV detection. With conductivity detection, this quantification is not possible or difficult due to the very large chloride peak. The actual sample is a refining process liquid with a high chloride content. As the sample solution also contains organic material, Inline Dialysis is applied to protect the analytical column. The combination of the two detection modes and the Inline Dialysis option reduces manual sample preparation and substantially increases the accuracy of the analysis.

Food waste is an important raw material for biogas production. However, during the fermentation process, phenylacetate can be produced from phenylalanine. As phenylacetate inhibits bacterial growth and their metabolism, it is an important parameter to monitor in order to guarantee a successful fermentation process. Aside from phenylacetate, chloride, nitrate, sulfite, sulfate, phosphate, and thiosulfate are also determined in the fermentation broth sample.

In the petrochemical industry, natural gas is processed to remove contaminants and meet product specifications. Process contaminants include acidic gases such as hydrogen sulfide and carbon dioxide, which can corrode costly refinery equipment downstream. Typically, the acidic gases are removed via alkanolamine treatment using monoethanolamine (MEA) or methyldiethanolamine (MDEA). The amine solutions absorb the acidic gases, and then the amine compounds are removed from the natural gas. In addition to the acidic gases, heat stable salts (HSS) that remain in the natural gas are also corrosive to the treatment plants. These are also removed via gas sweetening and need to be determined in the used gas sweetening amine solution. Some typical heat stable salts of interest include acetate (1), formate (2), chloride (3), phosphate (4), sulfate (5), oxalate (6), thiosulfate (7), and thiocyanate (8).

Process water from flue gas desulfurization mainly contains sulfite and sulfate. Besides these two main components, other sulfur species may be formed in the process. This application describes the determination of such late-eluting sulfur species with ion chromatography applying a Dose-in gradient. The applied gradient profile enables the resolution of amidosulfonate, dithionate, and imidodisulfonate besides thiosulfate, thiocyanate, major anions, and acetate.

Anions in diesel, especially biodiesel, may cause harmful deposits in the engine. Determination with ion chromatography requires the transfer of the diesel anions into an aqueous solution, injectable to the IC. A typical method to transfer the anions into water is via Inline Extraction with subsequent Inline Dialysis prior to the injection (see AN-C-101 for a respective analysis of cations). In the actual Matrix Elimination method, diesel diluted with isopropanol is injected into an isopropanol stream and passed through a preconcentration column. Isopropanol washes off the diesel, and a subsequent rinsing step with ultrapure water removes excess isopropanol.

Simultaneous determination of hydrogen sulfide and mercaptans in petroleum products by potentiometric titration with silver nitrate using the Ag-Titrode.

Determination of alkyllead compounds in petrol (gasoline) after reaction with iodine monochloride by potentiometric titration with EDTA using the Cu-ISE.

This Application Note presents a potentiometric titration method for trace H2S analysis in water on an OMNIS system using silver nitrate and an Ag Titrode.

Determination of the bromine index in low-level standards by bivoltametric titration with bromide/bromate using a double Pt electrode.

This Application Note describes the determination of total content of Ba, Ca, Mg, Pb and Zn in unused lubricating oil by means of the Optrode (610 nm). An excess of EDTA is first added to the metals. Afterwards, the excess EDTA is titrated back with magnesium chloride solution up to the end point of the indicator Eriochrome Black T.

The acid number (AN) of insulating, transformer, and turbine oils is crucial to ensure safe operation, operating equipment control, and corrosion prevention. These oils generally have low AN specifications and their AN determination by manual color-indicator titration is difficult, especially when analyzing colored samples.Using a Titrator with a photometric sensor to detect the end point ensures that the titrations are always carried out under the same conditions. This greatly increases the precision and reliability of the results, which in turn results in improved monitoring for your operations.

Basic additives are added to petroleum products to inhibit corrosion as they have a neutralizing effect on acidic compounds, which are formed as a result of degradation processes. Total base number (TBN) indicates the amount of basic additives present and thus can be used as a measure for the degradation of the petroleum product.Using an automated titration system with a photometric sensor to detect the end point ensures that the titrations are always carried out under the same conditions. This improves the precision and reliability of the results.This Application Notes describes the fully automated photometric determination of TBN in used engine oil using the Metrohm Optrode for the indication of the methyl orange endpoint (at 520 nm).

Automated mixing of a suspension and a solvent in a 50 mL dosing unit can be used to add a well-defined amount of a suspension-solvent mixture to a sample solution without clogging the dosing unit and tubing by the undiluted suspension.The method is explained by means of the TAN determination of a petroleum sample using thermometric titration. For a better endpoint recognition, small amounts of a paraformaldehyde-solvent suspension are added (catalyzed endpoint thermometric titration).

Fresh as well as used petroleum products may contain acidic components as additives or degradation products. The acid number (AN) is a measure for the relative amount of acids present expressed as mg KOH per g sample. Moreover, AN is used as a quality parameter of lubricating oils both for assessing the quality of new formulations and as an indicator for the degradation of such formulations during service. The use of a pH electrode suitable for non-aqueous titrations ensures the reliable determination of the equivalence point. A flexible sleeve diaphragm facilitates its cleaning especially after use in heavily contaminated samples, such as in used engine oils. Using the correct electrode greatly increases the precision and reliability of the results. This Application Note describes the potentiometric determination of the acid number according to ASTM D664 and IP 177 using the pH electrode Solvotrode easyClean.

Basic chemicals are added to petroleum products to prevent corrosion as they neutralize acidic components that form during the use and aging of these products. The base number (BN) gives an indication regarding the amount of these basic additives present, and it can be used as a measure for the degradation of the petroleum product.This Application Note describes the potentiometric determination of the base number according to ISO 3771, ASTM D2896, and IP 276 using the Metrohm Solvotrode easyClean and a fully automated OMNIS system.

This Application Note describes the conductometric determination of the total base number in engine oil according to IP 400.

This Application Note presents a modified time-saving method to determine iodine value (IV) in edible oils based on several standards (EN ISO 3961, ASTM D5554, etc.).

Potentiometric titration with silver nitrate can be used for the determination of mercaptans in refinery products. This Application Note describes their automatic determination in a middle distillate sample (gas oil).

Alkalinity is well-suited as a means of describing the capacity of a body of water to neutralize acid contaminations. It is therefore an important indicator for estimating the influence of contaminations on the ecological system.

The pHe is a measure of acid strength in alcohol fuels and in ethanol. It can be used as predictor of the corrosion potential of an ethanol-based fuel. The determination of the pHe is preferred over the total acidity, because total acidity overestimates the contribution of weak acids (e.g., carbonic acid) and underestimates the contribution of strong acids (e.g., sulfuric acid). Furthermore, the acid strength is an important parameter to determine in order to reduce the risk of failing motors.This Application Note describes the determination of the pHe value using the 913 pH Meter and the EtOH Trode according to ASTM D6423, which covers denatured fuel ethanol and ethanol fuel blends.

The hydroxyl number is an important sum parameter for quantifying the presence of hydroxyl groups in a chemical substance. As a key quality parameter, it is regularly determined in various polymers like resins, paints, polyesterols, fats, and solvents. Unlike other standards, EN 4629-2 works pyridine-free and without refluxing at elevated temperatures for a longer time. The determination is based on the catalytic acetylation of the hydroxyl group. It is performed at room temperature, requires only a small sample volumen, and can be fully automated.This Application Note describes the potentiometric determination of the hydroxyl number in 1-octanol and polyethylene glycol according to EN 4629-2. Using the OMNIS DIS-Cover technique, all sample preparation steps can be fully automated. Furthermore, the use of an OMNIS Sample Robot allows parallel analysis of multiple samples. The average time per analysis for one sample is thus reduced from approximately 49 min to 25 min., considerably increasing productivity in the laboratory.

Fully automated determination of the total acid number and total base number in engine oils according to ASTM D664 and ASTM D2896 is possible with the OMNIS Titrator.

For titrations in low conducting media (e.g., non-aqueous titrations) the potentiometric indication can be disturbed by interfering signals. When differential amplification is used, these signals are measured by both the measuring electrode and the reference electrode and thus neutralized. It is therefore possible to obtain smoother titration curves and more reproducible results.This Application Note describes the potentiometric determination of the acid number and base number in used motor oil by the differential amplification using a fully automated OMNIS system.

The bromine number is an important parameter for the determination of aliphatic C=C double bonds in petroleum products. The bromine number is usually determined using electrochemical titration at 5 °C, where the bromine is generated in situ from a bromide/bromate solution. For the titration, a solvent mixture of glacial acetic acid, methanol, and chloroform is used. In this Application Note, the toxic chloroform was replaced with diethyl carbonate.

The pHe value is an indicator for the acid strength and shows the presence of strong acids or bases in ethanol. In Europe, ethanol is used as a blending component in gasoline and needs to have a pHe value between 6.5 and 9.0.This Application Note describes a fast and accurate determination of the pHe value using the EtOH-Trode.

The bromine number indicates the degree of unsaturation and relies on the simple addition of bromine to the double bonds of alkenes. One mole of bromine is consumed for each mole of carbon-carbon double (C=C) bond present in a substance. In petroleum products, the bromine number corresponds to the olefin content.Normally, chlorinated solvents are used for the determination of the bromine number. In this Application Note they have been replaced by toluene. This makes the determination more ecological. The titration is performed automatically on an OMNIS system in combination with a double Pt-wire electrode. With this setup, a fast and accurate determination by potentiometric titration can be realized.

Compounds with carbonyl groups can be prone to oxidation for which reason their stability often decreases during storage or processing. The method presented here is suitable for the determination of aldehydes and ketones sparingly soluble in water.Samples are dissolved in deionized water. After a reaction with the hydroxylamine hydrochloride at 50 °C, carbonyl groups are quickly and accurately determined by potentiometric titration using the dUnitrode and sodium hydroxide as titrant.

Carbonyl compounds occur in many products such as bio-oils and fuels, solvents, flavors, and mineral oils. Carbonyl compounds are often prone to oxidation and thus their content has an influence on stability during storage or processing. Especially for pyrolysis bio-oils, stability issues are observed during storage, handling, and upgrading.Oils are dissolved in isopropanol. After a reaction with the hydroxylamine hydrochloride at 50 °C, a fast and accurate determination by potentiometric titration using the dSolvotrode and tetra-n-butylammonium hydroxide as titrant is performed.

Denatured fuel ethanol may contain additives such as corrosion inhibitors and detergents as well as contaminants from manufacturing that can affect the acidity of produced ethanol fuel. An increased acid content in solvents could lead to a variety of problems like a shorter storage stability or chemical corrosion. Using the Optrode with phenolphthalein as indicator, the acidity is determined as acetic acid by titration with sodium hydroxide as titrant.

Denatured fuel ethanol may contain additives such as corrosion inhibitors and detergents as well as contaminants from manufacturing that can affect the acidity of produced ethanol fuel. An increased acid content in solvents could lead to a variety of problems like a shorter storage stability or chemical corrosion.Using the dSolvotrode for indication, the acidity is determined as acetic acid by titration with sodium hydroxide as titrant.

Corrosion of metallic components is an inherent problem for engines, because metals naturally tend to oxidize in the presence of water and/or acids. Increased acid content is indicated by a low pH value, and could lead to a variety of problems like a shorter storage life (stability) or a reduced buffer capacity of the used engine coolant or antirust.In this Application Note, engine coolants or antirust samples are dissolved in water, and the pH measurement using the Profitrode is carried out according to ASTM D1287.

Corrosion of metallic components is an inherent problem for engines, because metals naturally tend to oxidize in the presence of water and/or low pH value. The reserve alkalinity of engine coolants and antirusts is a measure of the buffering ability to absorb acidity. The reserve alkalinity is frequently used for quality control during production and often listed in the specifications of the coolants. A fast and accurate determination is therefore important.This Application Note describes the straightforward determination of reserve alkalinity according to ASTM D1121. Using a fully automated system allows an accurate and reliable determination due to the reduction of human errors. Furthermore, the operator is free to carry out other tasks increasing the efficiency of the laboratory.

The presence of acidic components in volatile solvents could be a result of contamination, decomposition during storage, distribution or manufacture. An increased acid content in solvents could lead to a variety of problems like shorter storage stability or chemical corrosion. Using the Optrode for indication, the acidity is determined by photometric titration with sodium hydroxide as titrant and phenolphthalein as indicator. If the volatile solvent is water soluble, it is dissolved in deionized water, if not, it is dissolved in carbon-dioxide free ethanol.