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Glycolate and lactate have to be determined in a dual phase varnish remover. Analyzed is only the upper aqueous phase. The separation is achieved on a Metrosep A Supp 16 - 250/4.0 column. The eluent composition is adapted to get a sufficient separation of glycolate and lactate without interference by formate and acetate. Conductivity detection after sequential suppression is applied.

Pyrophosphate is used as a stabilizer in aqueous hydrogen peroxide solution. “Reagent grade” solutions may contain pyrophosphate in the higher mg/L range, while “electronic grade” hydrogen peroxide should be free of this stabilizer. Here the determination of pyrophosphate in a high purity H2O2 solution (30%) is performed applying Inline Preconcentration with Matrix Elimination (MiPCT-ME) and a Dose-in Gradient.

Ion chromatography (IC) is the method of choice to determine the concentration of common ions in water. This information is crucial as drinking water must meet certain standards to guarantee health (e.g., nitrite and nitrate), as well as technical suitability (e.g., corrosiveness of chloride and sulfate). The Eco IC is an ion chromatograph suitable for economical routine water analysis. Using an A Supp 17 anion column, the analysis of major anions in drinking waters is robust and can be performed at ambient temperatures without additional temperature conditioning.

The Eco IC is an entry-level instrument that is particularly suitable for routine operations and water analysis. It is equipped with a conductivity detector and can be used both with and without chemical suppression. This Application Note describes the determination of anion content with the Metrosep A Supp 17 - 250/4.0 column. This column model is particularly suitable for water analysis at room temperature.

Monofluorophosphate is used in toothpaste to prevent dental caries. USFDA allows up to 1.5 g/kg fluoride corresponding to 11.5 g/kg sodium monofluorophosphate on over the counter (OTC) dentifices for adults and children above 6 years. Here, a toothpaste is analyzed for monofluorophosphate by ion chromatography applying conductivity detection after chemical suppression.

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.

The microbore Metrosep A Supp 4 - 250/2.0 column is particularly suitable for the analysis of anions in critical samples. A waste water sample is being analyzed in the current application. The sample requires only one filtration prior to injection on the Metrosep A Supp 4 - 250/2.0. The anions are quantified with the application of conductivity detection following sequential suppression.

Kjeldahl nitrogen is a typical titration application that follows digestion and ammonia distillation. The ASTM Standard D8001 now offers an alternative applying persulfate digestion followed by IC determination. No distillation is required. In addition, the method enables the determination of total nitrogen and total phosphorus. We show the results of control samples containing organic substances. As these substances are dissolved in ultrapure water, the nitrogen concentration found corresponds to Total Nitrogen and Kjeldahl Nitrogen.

N,N-dimethylglycine is an amino acid derivative found in plants and animals. The respective sodium salt is available as nutritional supplement. In this context it is expected to have athletic performance enhancer effects and acts against fatigue. It is also accepted as a poultry feed addition. The determination is performed applying a Dose-in Gradient with subsequent conductivity detection after sequential suppression. To enhance the selectivity of the separation, a combination of a Metrosep A Supp 7 - 250/4.0 and a Metrosep A Supp 16 Guard/4.0 was used.

Soluble tungsten and molybdenum are available in soil mainly as their oxosalts, tungstate and molybdate. Tungstate is rather a hazardous compound, which may interfere with plant growth. Molybdate, on the other hand, is a required micronutrient, required e.g. for nitrate fixation in legumes. Both can easily be determined after alkaline digestion with ion chromatography followed by conductivity detection after chemical suppression.

Eltrombopag is a pharmaceutical agent used in certain conditions of thrombocytopenia. As such it is an orphan drug. The molecule of Eltrombopag is a protonated aromatic carboxyl compound. Under ion chromatography condition (alkaline eluent), it can be deprotonated and can thus block ion exchanger sites on the column. This results in decreasing retention times over time. To avoid this, Inline Matrix Elimination is applied, where the protonated Eltrombopag is washed off the preconcentration column before injection. Nitrite is then analyzed with conductivity detection after sequential suppression.

Organic acids in wine are omnipresent in winemaking. Some of them are present already in the grape while others appear during fermentation. The sum of organic acids and their composition have a direct influence on the taste of the respective wine. In this application a wine is tested for minor organic acids, especially shikimic and iso-citric, besides typical acids and anions. The separation is performed by anion chromatography applying a low-pressure gradient to achieve the required selectivity.

Metrohm Inline Sample Preparation (MISP) is a collection of versatile, time- and cost- effective techniques reducing manual sample preparation. This Application Note describes the combination of Inline Dilution with Inline Ultrafiltration. Samples are automatically diluted and subsequently filtered before injection. MagIC Net allows to run intelligent dilution by checking results and rediluting the sample if the result is out of the calibration range. Also the multipoint calibration is performed by automatically diluting the stock standard solution. In this way, an automatic calibration of each analyte is effectively achieved.

EN ISO 10304-1 is one of the most important standards for the determination of the seven standard anions in water samples. Many other standards refer to EN ISO 10304-01 if anion determination by IC is required. This standard asks for a membrane filtration for samples to avoid bacteria and solids, if required. This application shows the determination of anions according EN ISO 10304-1 applying Inline Ultrafiltration. This setup avoids tedious manual sample filtration and handles any samples fully automatically.

Ultrapure chemicals are required in the semiconductor industry. Ionic impurities may lead to compromised products. This application describes the determination of anionic impurities in semiconductor grade 28% ammonium hydroxide solution. To avoid matrix disturbances, Inline Neutralization and Inline Preconcentration with Matrix Elimination needs to be applied.

Determination of arsenic in dust from a waste incineration plant is performed. This is required as the environmental risk depends on the degree of oxidation of the arsenic species. Due to the different pKa of the respective anions, selenite requires non-suppressed conductivity detection, while arsenate is best determined with suppression. The determination of both species is achieved by switching the suppressor in and out, respectively.

Perchlorate is known as a potential contaminant in drinking water. Besides very few natural sources, it mainly originates from disinfectants, bleaching, propellants, etc. EPA method 314.0 requires to reach a method detection limit of 0.5 µg/L for perchlorate in reagent water. But also water with a very high content of total dissolved solids needs to be analysed by this method. Making use of the Metrosep A Supp 7 - 250/4.0 column fulfills all requirements of this method.

The STREAM (suppressor treatment reusing eluent after measurement) is applied since quite some time. The suppressor rinsing with suppressed eluent is advantageous over ultrapure water rinsing: a smaller water dip, faster MSM equilibration, and the avoidance of an additional water supply are just a few. Injecting samples containing iron in the matrix under sulfuric acid regeneration yields reduced peak areas and broader peaks for phosphate. Switching to a regenerant based on sulfuric and oxalic acid allows full regeneration of the MSM. The overlay above shows three subsequently taken chromatograms after more than 300 injections of 10 mg/L iron(II) onto one single MSM chamber. No difference in peak shape or peak area is observed.

Pamidronate is applied to treat osteoporosis by strengthening the bones. It is a bisphosphonate containing a primary amine group. Phosphite and phosphate are related compounds, which need to be quantified. USP requires the use of formic acid eluent with refractive index detection. But a standard IC procedure offers an alternative with better sensitivity. Phosphite and phosphate are analyzed with conductivity detection after sequential suppression.

Within the scope of the modernization of USP, chloride and sulfate are determined as impurities in potassium hydrogen carbonate (bicarbonate). USP41 monograph for potassium bicarbonate does not check for chloride and sulfate. Applying ion chromatography with conductivity detection after sequential suppression allows quantifying these impurities.

Determination of disinfection byproducts in water is a standard application for ion chromatography. Applying conductivity detection the separation of chlorite and bromate from chloride is crutial for μg/L detection limits. The combination of a Metrosep A Supp 7 - 250/4.0 and a Metrosep A Supp 16 Guard/4.0 lead to an improved separation. The Limit of Quantification for bromate is around 1 μg/L

Lithium-ion (Li-ion) battery electrolyte quality is essential for performance, stability, and safety reasons. Ion chromatography is an accurate method for electrolyte analysis.

Potassium chloride and potassium bicarbonate effervescent tablets are used to prevent potassium deficiency. Pharmaceutical manufacturers and labs adhere to strict quality regulations using USP-NF monographs. Ion chromatography with suppressed conductivity detection, utilizing the Metrosep A Supp 16 - 100/4.0 (L91) column, is approved by the USP to quantify chloride content in these tablets, following validation per USP General Chapter <621>.

Fluoride is commonly used in dental products to help prevent tooth decay. If the products are intended to prevent the formation of cavities (carries), then it is regulated by the US Food and Drug Administration (USFDA) as an Over-the-Counter (OTC) Drug. Previously, the assay of Fluoride in oral solution was done by Ion selective electrode and identification was done by tedious wet chemistry method. USP has updated this monograph for Assay and identification tests with Ion Chromatography using L46 packing. The Metrosep A Supp 1 - 250/4.6 column fulfills all USP acceptance criteria. It therefore is a viable alternative separation column for the determination of sodium fluoride in oral solutions.

Dental care products often contain sodium fluoride as an active ingredient. Manufacturers use the United States Pharmacopeia and National Formulary (USP-NF) Monograph «Sodium Fluoride» to quantify sodium fluoride and its anionic contaminants chloride and acetate in these products. The validated USP method proposes ion chromatography (IC) with suppressed conductivity detection to carry out the fluoride assay as well as the impurity determination in a single chromatogram.

Sodium fluoride gel for pharmaceutical use needs to comply with USP requirements. The actual monograph (USP 42) uses two different methods for the identification and the assay. Ion chromatography allows the analysis of these two parameters in one single determination. In the course of the USP monograph modernization, this ion chromatographic approach makes this type of analysis even easier.

«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.

Sodium fluoride tablets for pharmaceutical use need to comply with U.S. Pharmacopeia (USP) requirements. Ion chromatography (IC) with suppressed conductivity detection has been approved by the USP as a validated method to quantify fluoride content in sodium fluoride tablets. In the course of the USP monograph modernization, using automated IC makes this type of analysis even easier.

Ion chromatography (IC) with suppressed conductivity detection has been approved by the U.S. Pharmacopeia (USP) as a validated method to quantify the monofluorophosphate (MFP) content in sodium monofluorophosphate. This Application Note shows that all acceptance criteria for the USP Monograph «Sodium Monofluorophosphate» are fulfilled and the procedure was approved as a validated USP method.

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.

OpenLab CDS is the newest generation of chromatography data systems from Agilent, combining chromatography and mass spectrometry in a single software platform. The Metrohm IC Driver for OpenLab CDS integrates Metrohm IC instrumentation for full control and data acquisition. The present application describes the simultaneous analysis of anions and cations in a soft drink with a dual channel IC system. Eluent is prepared by applying Inline Eluent Production.

OpenLab CDS is the newest generation of chromatography data systems from Agilent. The Metrohm IC Driver 1.0 for OpenLab CDS implements Metrohm ion chromatographs in OpenLab CDS for full control and data acquisition. This application shows the use of a gradient (Dose-in Gradient) as well as Dosino Regeneration in OpenLab CDS. Fluoride, chloride, nitrite, bromide, nitrate, sulfate, phosphate, and iodide in a standard solution are separated and determined.

OpenLab CDS is the newest generation of the Agilent chromatography data systems platform. The Metrohm IC Driver 1.0 for OpenLab CDS enables introducing Metrohm IC instruments to this platform for full control and data acquisition. This application shows the analysis of iodide by amperometric detection, enabling detection at trace levels. The eluent is produced automatically by the 941 Eluent Production Module. In this way, amperometric detection can be executed with the same functionality and performance as with MagIC Net.

Stannous fluoride gel for pharmaceutical use needs to comply with USP requirements. The actual monograph (USP 42) utilizes two different methods for the identification and the assay. Ion chromatography allows the analysis of these two parameters within a single determination. In the course of the USP monograph modernization, this ion chromatographic approach makes this type of analysis even easier.

Sodium fluoride and phosphoric acid gel for pharmaceutical use need to comply with USP requirements. The actual monograph (USP 42) uses two different methods for the identification and the assay. Ion chromatography allows the measurement of these two parameters within a single determination. In the course of the USP monograph modernization, this ion chromatographic approach makes this type of analysis even easier.

The TitrIC flex II system is the perfect combination of titration, direct measurement, and ion chromatography for fully automated analysis of all key parameters. These include pH, conductivity, hardness, anions, cations, as well as the calculation of the ion balance: comprehensive water analysis from one system.

In the course of USP column equivalency tests, the Metrosep A Supp 3 - 250/4.0 is applied for the assay of citric acid/citrate and phosphate according to USP general Chapter <345>. This report shows that the Metrosep A Supp 3 - 250/4.0 column is equivalent to packing L61 required in USP general Chapter <345>.

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.

Sulfamic acid is a reasonably strong acid, used in descaling agents and for cleaning of dairy and brewing equipment. Here, a chemical solution is analyzed for sulfamate, chloride, nitrite, nitrate, and sulfate. As the solution can also contain hydramine, sufficient separation from the ions of interest is required.

The semiconductor industry requires high-purity or even ultrahigh-purity chemicals for the production of electronic components. The purity of the chemicals is crucial for the quality and efficient production of the parts. Here, hydrogen peroxide and ammonium hydroxide are analyzed applying traditional sample preparation methods like digestion and evaporation with subsequent reconstitution with ultrapure water. The received samples are injected applying intelligent Preconcentration Technique (MiPCT).

Analysis of sodium hydrogen carbonate (also known as sodium bicarbonate) for anionic contaminants is critical due the large amount of CO2 formed during suppression. Even applying sequential suppression does not completely remove the interferences due to the carbonate peak. The introduction of Inline Neutralization applying the Sample Preparation Module (SPM) with subsequent CO2 removal with the MCS (Metrohm CO2 Suppressor) prior to the injection solves the problem. After this pretreatment, the sequentially suppressed sample is analyzed without issues.

Forensic institutes examine terrorist attacks and warfare agents via trace detection analysis of the used explosives and their residuals. Of particular importance is the acquisition of «chemical fingerprints» for criminal investigation departments and governmental security agencies. Institutes for public health and environmental protection analyze such compounds that can contaminate the underlying soil and infiltrate ground water.Forensic investigation with ion chromatography (IC) using suppressed conductivity detection allows a sensitive and robust determination of anionic contaminants such as chlorate, thiosulfate, thiocyanate, and perchlorate next to the common inorganic anions over a broad concentration range.

Monitoring the range of organic acids in wine is crucial to improve flavor and quality, and to fulfill universal standardized criteria such as the International Code of Oenological Practices. Analytically, organic acids can be properly determined with ion chromatography (IC) and suppressed conductivity detection. As a multicomponent method, inorganic acids can also be resolved which are also valuable tracers for wine quality and taste. This Application Note presents two IC methods for wine quality analysis: a fast isocratic screening method of major organic acids and anions including sulfite, and a complex monitoring method with a binary gradient to separate 15 organic acids. Inline Ultrafiltration was used for economical sample treatment.

As an alternative to titration, ion chromatography (IC) with suppressed conductivity detection has been approved by USP as validated method to quantify chloride content in NaCl tablets for solution or oral use.

An ion chromatography (IC) assay with suppressed conductivity detection is the standardized way to accurately quantify phosphate in phosphates compounded injections.

Anticavity pharmaceuticals like sodium fluoride and acidulated phosphate topical solution products require strict quality control. This Application Note outlines the fluoride IC assay as described in the USP Monograph Sodium Fluoride and Acidulated Phosphate Topical Solution.

In severe cases of cyanide poisoning, sodium nitrite is used along with sodium thiosulfate for treatment. This Application Note describes the nitrite ion chromatography assay with the Metrosep A Supp 4 column and suppressed conductivity detection. This column equivalency study was in cooperation with the USP according to the USP General Chapter <621>.

Nitrosamine presence in medicines, even at trace level poses high safety risks to patients (carcinogenic). Nitrosamine formation can be avoided by controlling and monitoring the nitrite concentration in pharmaceutical products and substances. This Application Note describes the analysis of nitrite in duloxetine hydrochloride with ion chromatography (IC).

Nitrosamine formation can be avoided by controlling the nitrite concentration in pharmaceutical products and processes. To monitor nitrosamine formation, sensitive analytical methods such as ion chromatography for the determination of nitrite in pharmaceutical products and substances are essential.

N-Methylpyrrolidone (NMP) is crucial for lithium-ion battery production. Metrohm’s intelligent Preconcentration Technique with Matrix Elimination enables µg/L-level anion analysis in NMP.

The Metrosep A Supp 21 column and 948 Continuous IC Module, CEP enable efficient, automated single-run analysis of major anions and disinfection byproducts in water.

Supercapacitors (also known as ultracapacitors, electrochemical capacitors, or double-layer capacitors) are electrochemical devices that have the ability to store and release charge and deliver high power densities over short periods of time. Their ability to store electrical energy efficiently and release electrical energy very quickly make them ideally suited for applications where short time backup power and peak power needs are critical.

Spectroelectrochemical experiments not only provide outstanding qualitative information about samples, but also offer other quantitative data that can be considered when performing analyses. A single set of experiments allows analysts to obtain two calibration curves: one with the electrochemical data and another with the spectroscopic information. The concentration of tested samples is calculated by using both curves, confirming the obtained results by two different routes. In this Application Note, comparison between electrochemical and spectroscopic determinations demonstrates that the two methods measure uric acid (UA) indistinctively, with close agreement of the calculated values with empirical data.

In-situ spectroelectrochemistry provides dynamic electrochemical and spectroscopic information concurrently with the redox reaction occurring on the electrode surface. Although different spectroelectrochemical configurations can be used, simple equations explain how to relate electrochemistry and spectroscopy for each experimental setup. This Application Note describes how the quantification of one electrochemical parameter (the diffusion coefficient) is calculated from the spectroscopic data as a proof of this concept.

The development of a novel reflection cell for conventional electrodes facilitates the performance of spectroelectrochemical measurements. This device allows researchers to work in aqueous solutions as well as in organic media due to its chemical resistance.

Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most promising ICPs due to its high conductivity, electrochemical stability, catalytic properties, high insolubility in almost all common solvents and interesting electrochromic properties (transparent in the doped state and colored in the neutral state). In this Application Note, PEDOT film is evaluated by spectroelectrochemical techniques.

This Application Note demonstrates square wave voltammetry for sensitive, reproducible quantification of paracetamol using a screen-printed electrode and INTELLO.

This Application Note presents DPV as a sensitive, selective method for detecting heavy metals in water, detailing setup, parameters, and advantages over other techniques.

Determination of chloride in canned vegetables by potentiometric titration with silver nitrate using the Ag-Titrode.

In order to maintain product quality, the sodium chloride content in meat products must be monitored, as the limit values defined by the respective public health authorities must not be exceeded. The chloride content in food correlates with the salt content, its determination is therefore described in various norms and standards. However, preparation of meat samples is time consuming, as it requires homogenization with a mixer and a chloride extraction with water.In order to reduce workload and working hours, this Application Note describes a fully automatic potentiometric titration of chloride with silver nitrate in meat products based on ISO 1841-2, including fully automated sample preparation using a Polytron homogenizer.

Determination of trace chloride in cement and clinker by potentiometric titration with silver nitrate using the Ag-Titrode.

Determination of sulfate in brine by indirect potentiometric titration with EGTA using platinum and tungsten electrodes.

Determination of sulfate in cement by indirect potentiometric titration with EDTA using platinum and tungsten electrodes.

Determination of anionic surfactants in shower lotions and shampoos by potentiometric titration with TEGO®trant A100 using the «Ionic Surfactant» electrode.

Determination of anionic surfactants in a nickel plating bath by potentiometric titration with TEGO®trant A100 using the «Ionic Surfactant» electrode.

Determination of cationic surfactants in hair conditioner by potentiometric titration with dioctyl sodium sulfosuccinate using the «Ionic Surfactant electrode.

Determination of the cationic surfactant «cetrimide» in an antiseptic disinfectant by potentiometric titration with sodium dodecyl sulfate using the «Ionic Surfactant» electrode.

Determination of chlorhexidine in wash lotion by potentiometric titration with sodium tetraphenylborate using the NIO surfactant electrode.

This application note shows a reliable way to determine the content of non-ionic surfactants in liquid cleaning solutions by potentiometric titration.

Determination of nonionic surfactants in compact washing powders by potentiometric titration with sodium tetraphenylborate using the NIO surfactant electrode.

Determination of ampicillin in raw and pure products through potentiometric titration with Hg(II) using the combined Au electrode. Keyword: Antibiotics

Determination of total penicillin content through potentiometric titration with Hg(II) using the combined Au electrode. Keyword: Antibiotics

Simultaneous determination of cyanide and silver in a silver plating bath by potentiometric titration with silver nitrate using the Ag-Titrode.

Determination of Cr(VI) and Cr(III) in chromium baths by iodometric potentiometric titration with thiosulfate using the combined Pt electrode.

Determination of Sn(II) and sulfuric acid in an acidic tin plating bath by potentiometric titration.

Determination of cyanide in alkaline plating baths by potentiometric titration with silver nitrate using the Ag-Titrode.

Determination of hydroxide and carbonate in alkaline plating baths by potentiometric titration with HCl using the combined glass electrode.

Determination of cadmium, copper, lead, and zinc in alkaline plating baths by potentiometric titration with EDTA using the Cu-ISE.

Peroxides are often used for disinfection and water treatment purposes due to their antiseptic properties. Lower concentrations between 0.3–3% are used in households, while higher concentrations can be used for sterilization purposes. Additionally, peroxides are utilized as oxidizing and bleaching agents. Peroxides, perborates, and percarbonates can easily be determined by titration. This application note presents two titration methods for peroxide analysis: ASTM D2180 for concentrated hydrogen peroxide solutions, and a second method for trace determination of hydrogen peroxide, suitable for concentrations as low as 0.4 mg/L.

Determination of perborate, percarbonate, or persulfate in washing powder by iodometric potentiometric titration using the Pt-Titrode.

Determination of the alkalinity of gas washing solutions containing alkanolamines by potentiometric titration with sulfuric acid using the combined glass electrode.

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.

Determination of Na2O and SiO2 in water glass by potentiometric titration with HCl using the Sb electrode.

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 lidocaine in ointments by potentiometric titration with sodium tetraphenylborate using the NIO surfactant electrode.

Determination of hydrofluoric and nitric acid in etching baths by potentiometric titration.a) Determination of the total acid content using the combined Sb electrode and NaOH as titrant.b) Determination of hydrofluoric acid using the F-ISE and the titrant La(NO3)3.The concentration of nitric acid is then determined by calculation.

Determination of tranexamic acid in injection solutions by nonaqueous potentiometric titration with perchloric acid using a glass electrode.

Determination of benzydamine hydrochloride {1-benzyl-3-[3-(dimethylamino)-propoxy]-1H-indazole hydrochloride} in disinfectant solution by potentiometric titration with sodium tetraphenylborate using the NIO surfactant electrode.

Determination of the nitrogen content of nitrocellulose by potentiometric titration with Fe(II) using a combined Pt electrode.

Determination of the iron content of iron powder by potentiometric titration with potassium dichromate using the Pt-Titrode.

Determination of free alkali in sodium hypochlorite by potentiometric titration with hydrochloric acid using a combined glass electrode.

Determination of phenylglycine through nonaqueous potentiometric titration with sodium methylate using a special combined glass electrode. Keyword: Antibiotics

Citric acid and oxalic acid are present in many products, such as foods or chemical solvents (e.g., decontamination solutions). Both acids are reducing agents and citric acid is additionally a powerful antioxidant. Due to their mutual impact (buffer effect), a content calculation is only possible with correction factors for each acid. A fast and accurate determination by potentiometric titration using the dEcotrode plus and sodium hydroxide as titrant can be realized in this Application Note.

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

Determination of acetate, chloride, and phosphate in an infusion solution by potentiometric titration with sodium hydroxide after conversion of the anions to the corresponding acids.

Determination of the soap content of soap noodles by potentiometric titration with TEGO®trant A100 using the «Ionic Surfactant» electrode.

Determination of soaps and anionic surfactants in washing powder by potentiometric two-phase titration with TEGO®trant A100 using the «Surfactrode Resistant» electrode.

Determination of anionic surfactants in shower oil by potentiometric two-phase titration with TEGO®trant A100 using the «Surfactrode Resistant» electrode.

Determination of cationic surfactants in a household cleaner by potentiometric two-phase titration with sodium dodecylsulfate using the «Surfactrode Resistant» electrode.

This application note describes the determination of nonylphenol ethoxylate by potentiometric titration with sodium tetraphenylborate using the NIO surfactant electrode.

Due to its price and wide availability, the anionic surfactant sodium lauryl sulfate (SLS; SDS) can be found in many detergents as an emulsifier or as a fat solvent e.g., in cleaning or cosmetic products. To avoid causing severe dry skin and hair, and thus skin irritation, regulations in many countries have restricted the sodium lauryl sulfate concentration in ready-to-use products to a range between 0.05–2.5% SLS. To control the concentration of SLS in different products, a titration is carried out with TEGO® trant A100 and the Optrode. The evaluation is done automatically by means of a software, leading to reliable and reproducible results.

Determination of lauryl ether sulfate (LAES) by potentiometric/turbidimetric titration with TEGO®trant A100 using the 610 nm Spectrode.

Determination of calcium in aqueous solutions by photometric titration with EDTA using the 610 nm Spectrode.

Determination of the sum of calcium and magnesium in cement by photometric titration with EDTA using the 610 nm Spectrode.

Determination of aluminum in cement by photometric back-titration of the EDTA excess with zinc sulfate using the 610 nm Spectrode.

Determination of traces of calcium in brine by photometric titration with 1,2-diaminocyclohexanetetraacetic acid using the 610 nm Spectrode.

Determination of nitrite in aqueous solutions by potentiometric back-titration of the added permanganate excess with ammonium iron(II) sulfate using the Pt-Titrode.

Determination of citrate in mineral water drinks by potentiometric titration with copper sulfate using the Cu-ISE. Before the determination, the sample is degassed and passed through a cation-exchange resin.

Simultaneous determination of titanium and iron by potentiometric titration with potassium dichromate using a platinum electrode. Before determination, Ti4+ and Fe3+ are reduced with Cr2+.

Determination of the antihistamine astemizole in raw products by nonaqueous potentiometric titration with perchloric acid using separate electrodes.

Determination of calcium in cheese by potentiometric titration with EGTA using the Cu-ISE.

Tallow amine ethoxylates are toxic to aquatic life, and therefore their use is restricted. This Application Note explains an approach to determine these non-ionic surfactants potentiometrically.

This application note shows how coconut oil ethoxylates can be determined via potentiometric titration.

Determination of iron and nickel in binary mixtures by potentiometric titration with EDTA at different pH values using the Cu-ISE.

Determination of calcium pantothenate by nonaqueous potentiometric titration with perchloric acid using separate electrodes.

Determination of palladium(II) by potentiometric titration with hexadecylpyridinium chloride using the «Ionic Surfactant» electrode.

Determination of reducing sugars in wine and candies according to Fehlings method by potentiometric/iodometric titration using the Pt-Titrode.

The automated system Basic water analysis determines conductivity, pH value, and alkalinity in all kind of water samples. The high degree of automation (e.g., automated sample addition, automated calibration as well as automated titer and cell constant determination) minimizes errors and guarantees an outstanding reproducibility.

In this application note, a fully automated system is presented which allows the determination of several parameters according to various standards within one analysis. These include conductivity (ISO 7888, EN 27888, ASTM D1125, EPA 120.1), the pH value (EN ISO 10523, ASTM D1293, EPA 150.1), alkalinity (EN ISO 9963, ASTM D1067, EPA 310.1), and Ca/Mg content (ISO 6059, ASTM D1126, EPA 130.2). Additionally, the system transfers the required sample volume into an external titration vessel for the analysis, reducing manual sample preparation. Furthermore, all sensors can be automatically calibrated and the titer of each titrant can also be determined.

In this application note, a fully automated system is presented which allows the determination of several parameters according to various standards within one analysis. These include conductivity (ISO 7888, EN 27888, ASTM D1125, EPA 120.1), pH value (EN ISO 10523, ASTM D1293, EPA 150.1), alkalinity (EN ISO 9963, ASTM D1067, EPA 310.1), and chloride content (ISO 9297, ASTM D512, EPA 325.3). Additionally the system transfers the required volume of sample into an external titration vessel, further reducing manual sample preparation. Furthermore, all sensors can be calibrated automatically and the titer of each titrant can also be determined.

In this application note, a fully automated system is presented which allows the determination of several parameters according to various standards within one analysis. These include conductivity (ISO 7888, EN 27888, ASTM D1125, EPA 120.1), pH value (EN ISO 10523, ASTM D1293, EPA 150.1), alkalinity (EN ISO 9963, ASTM D1067, EPA 310.1), Ca/Mg (ISO 6059, ASTM D1126, EPA 130.2), and chloride (ISO 9297, ASTM D512, EPA 325.3). Additionally the system transfers the required volume of sample into external titration vessels for the different analyses, reducing manual sample preparation. Furthermore, all sensors can be automatically calibrated and the titer of each titrant can also be determined.

This Application Note describes the photometric determination of sulfate in aqueous solutions using the Optrode (520 nm). Sulfate is precipitated with an excess of barium chloride solution. Excess barium is subsequently titrated with EDTA.

This Application Note describes the photometric determination of aluminum in cement using the Optrode (574 nm). Following breakdown of the cement sample, the dissolved aluminum is titrated with EDTA. The excess EDTA is titrated back with zinc sulfate solution.

This Application Note covers the photometric determination of calcium in cement using the Optrode (610 nm). After digestion of the cement sample, calcium is titrated with EDTA to the murexide endpoint.

This Application Note describes the digestion of a cement sample and the photometric determination of iron in accordance with DIN EN 196-2 by means of Optrode at 610 nm. Sulfosalicylic acid is used as the indicator and EDTA as the titrant for the determination.

This Application Note is devoted to the photometric determination of magnesium in cement using the Optrode (610 nm). After digestion of a sample aliquot, the magnesium content is determined using EDTA titration.

This Application Note treats the photometric titration of nickel using the Optrode (520 nm). Murexide was used as the indicator and EDTA as the titrant.

This Application Note details the photometric determination of chondroitin sulfate with 1-hexadecylpyridinium chloride as titrant and with the Optrode (660 nm). The method is in compliance with the Ph. Eur. and the USP.

ASTM D8192 describes the photometric titration of the total hardness, calcium hardness, and magnesium hardness in water with an optical sensor for objective endpoint indication, increasing precision and reliability. The method is suitable for both colored and colorless samples such as groundwater, surface water, wastewater, and drinking water. Using a fully automated OMNIS system equipped with an Optrode ensures that the sample preparation and analysis are repeatable.

This Application Note describes the photometric determination of sulfate using the Optrode (610 nm). Sulfate is titrated with a lead nitrate solution; dithizone is used as indicator.

Vitamin C, also known as ascorbic acid or L-ascorbic acid, is an essential nutrient involved in the repair of tissues and the enzymatic production of certain neurotransmitters. It is required for the functioning of several enzymes and immune performance, and is also an important antioxidant. This nutrient is found in many foods and is often used as a dietary supplement.This Application Note describes the photometric determination of ascorbic acid according to the standard ISO 6557-2. To increase the objectivity on the determined equivalence point and the reproducibility of the results, an autotitrator equipped with a photometric sensor, the Optrode, is used. The titrant 2,6-Dichlorophenol-indophenol (DCIP or DPIP) simultaneously serves as titrant and indicator.

The carboxyl end groups (CEG) in polymers, such as polyethylene terephthalate (PET), are a measure of the number of unreacted carboxylic acid groups at each end of a polymer chain. The number of CEGs may influence the hydrolysis resistance of geosynthetics, such as geogrids and geotextiles. The lower the CEG value the higher is the hydrolysis resistance of geosynthetics, which in turn increases their stability.This Application Note describes the photometric titration of carboxyl end groups in PET pellets using the Metrohm Optrode. The acidic end groups of the polymer are titrated with an ethanolic KOH solution using bromophenol blue as indicator.

This Application Note describes the photometric determination of bismuth nitrate using the Optrode (520 nm). The sample is titrated with EDTA solution past the endpoint; xylene-orange is used as the indicator. The method for bismuth nitrate fulfills the directives defined in the Ph. Eur. and the USP.

This Application Note looks at the photometric determination of manganese sulfate using the Optrode (610 nm). Manganese is titrated with EDTA; Eriochrome Black T is used as indicator. The method complies with Ph. Eur. and the USP.

This Application Note describes the photometric determination of zinc sulfate using the Optrode at a wavelength of 610 nm. Complexometric titration of zinc requires EDTA as titrant and Eriochrome Black T as indicator. The method fully complies with Ph. Eur. and USP.

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).

The automated system MATi 13 determines the permanganate index in all kind of water samples according to EN ISO 8467. The high degree of automation (e.g., automated sample addition, automated titer and blank value determination) minimizes errors and guarantees robust and reproducible results.

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.

The present Application Note describes an automated system with which the acidity can be determined in a wide variety of juice samples. The high degree of automation (e.g., automated calibration and titer determination) reduces errors to a minimum and offers outstanding reproducibility.

Acid copper baths are mainly used for the copper deposition on semiconductor wafers. Small amounts of chloride increase the speed of deposition and reduce anode polarization. However, higher concentrations are undesired, as this will decrease the quality of the copper deposition. Therefore, it is quite important to monitor the amount of chloride to have an effective, yet high-quality copper deposition process.In this Application Note, a fully automated solution based on titration is presented. In comparison to ion chromatography, titration offers the benefit that no dilution of the sample is necessary, and the hardware is comparatively low-priced. Furthermore, the fully automated solution allows users to minimize handling errors, to reduce workloads, and to guarantee outstanding reproducibility.

This Application Note describes an automated system with which the chloride content in various water samples can be determined. The high degree of automation (e.g., automated addition of acid and titer determination) reduces errors to a minimum and ensures outstanding reproducibility.

Titrants are normally bought ready to use. However, it is necessary to determine the accurate concentration of your titrant solution on a regular basis using a primary standard. To correct the mentioned variation, a so-called «titer factor» is applied. The titer can be easily and quickly assessed by using the Metrohm brand of autotitrators. Predefined calculation formulas implemented in Metrohm titrators or software, respectively, as well as the automatic storage of the titer factor, makes standardization a simple task.

In many countries, the aluminum concentration in water is limited to 0.2 mg/L. This application note shows how the analysis of aluminum in water can be done fully automatically by complexometric titration with EDTA.

This Application Note describes the fully automated complexometric determination of barium in aqueous solutions with a copper ion-selective electrode.

This application note shows how to determine the bismuth content automatically in aqueous solution with potentiometric titration.

In this Application Note, the determination of calcium in milk is shown with the copper ion-selective electrode which is less sensitive to contamination from proteins.

This Application Note describes the fully automated complexometric determination of total iron in cement with a copper ion-selective electrode.

This Application Note describes the fully automated complexometric determination of zinc(II) in aqueous solutions with a copper ion-selective electrode.

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.).

This Application Note details a method to determine the peroxide value of edible fats and oils based on EN ISO 27107, EN ISO 3960, AOAC 965.33, Ph.Eur. 2.5.5, and USP<401>.

The saponification value evaluates edible oil quality by indicating the average molecular weight of fatty acids. Its titrimetric determination in canola and olive oil is described here.

This Application Note describes the titration of acid value and free fatty acids in different edible oils, based on the standards EN ISO 660, USP<401>, and Ph.Eur. 2.5.1.

The hydroxyl number (HN) is an important sum parameter for quantifying the presence of hydroxyl groups in chemicals. As a key quality parameter, it is determined in various substances. For pharmaceutical samples, USP chapter <401> and Ph. Eur. Chapter 2.5.3 describe the determination. However these methods either use toxic pyridine and require refluxing or have long reaction times.In this Application Note, an alternative method according to ASTM E1899 is presented. This method is pyridine-free and does not require refluxing or long reaction times. The determination is performed at room temperature with only a small sample size. The analysis including all preparation steps is performed with a fully automatic OMNIS system. This allows parallel analysis of multiple samples, increasing productivity in the laboratory by 50%.

This Application Note describes the iodometric, bivoltametric determination of ascorbic acid in orange juice using the Double Pt-sheet electrode.

This Application Note describes the bivoltametric titration of ascorbic acid in orange juice. 2,6-dichlorophenol indophenol (DPIP) is used as titrant; endpoint determination takes place using the Double Pt-sheet electrode.

This Application Note describes automatic sulfate determination using a combined ion-selective calcium electrode. Sulfate is precipitated with an excess of barium chloride solution. Excess barium is subsequently back-titrated with a standard EGTA solution.

Aluminum and magnesium ion mixtures are analyzed using back-titration at different pH values. The ion-selective copper electrode is used here as the indicator electrode. First, the aluminum is determined in acidic solution and then the magnesium in alkali solution.

Zinc and magnesium ion mixtures are analyzed using back-titration at different pH values. The ion-selective copper electrode is used here as the indicator electrode. First, the zinc is determined in acidic solution and then the magnesium in alkali solution.

This Application Note describes an automated system with which the chloride content in bouillon can be determined. The high degree of automation (e.g., automatic addition of acid and titer determination) reduces errors to a minimum and ensures outstanding reproducibility.

Manganese in aqueous solution can be determined using back titration in alkali solution. The ion-selective copper electrode is used here as the indicator electrode.

This application note shows the use of an ion-selective copper electrode to measure the indium concentration in an aqueous solution.

Thallium in aqueous solution can be determined using back titration in a weak acidic solution. The ion-selective copper electrode is used here as the indicator electrode.

Zirconium can be analyzed quickly and easily in slightly acidic solutions with back titration. The ion-selective copper electrode is used in this Application Note to determine zirconium in aqueous solution.

Copper can be determined using photometric titration with EDTA at a wavelength of 520 nm.

This application note describes the analysis of cadmium in aqueous solution using a copper ion-selective electrode with Cu-EDTA complex used as an indicator.

This application note describes the fast, accurate determination of cobalt with a copper ion-selective electrode (Cu ISE) and Cu-EDTA complex as an indicator.

This Application Note describes the automated complexometric determination of copper with the Cu ISE.

Magnesium can be determined with the Cu ISE. A small amount of Cu-EDTA complex is used as an indicator, as the Cu ISE is not selective for magnesium itself.

Nickel can be determined with the Cu ISE. A small amount of Cu-EDTA complex is used as an indicator, as the Cu ISE is not selective for nickel itself.

Lead can be analyzed with the Cu ISE. Diammonium tartrate is added to the solution to prevent the precipitation of lead hydroxide in the alkali titration medium.

Water hardness is often determined photometrically using two different indicators and while performing the determination at two different pH values. Additionally, the determination itself is subjective, as the color change is determined by the analyst and not by an analytical device.This application note introduces a more robust option to easily assess calcium, magnesium, and total hardness in water by using the Cu-ISE and two different titrants. Sample preparation is identical for both analyses and can therefore be automated without any issues.

The titratable acidity gives an indication of the freshness of milk and yogurt as well as other fermented milk products. The determined titratable acidity in milk is mainly given through the absorption of hydroxyl ions by milk proteins and milk salts. The acidity increases with bacterial acidification and with enzymatic lipolysis. The titratable acidity corresponds to the amount of sodium hydroxide required to titrate 100 g sample to a pH value of 8.30.In this Application Note, an easy and accurate method to determine the titratable acidity in milk according to DIN 10316 and in yogurt according to ISO/TS 11869 and IDF/RM 150 is demonstrated.

In order to maintain product quality, the sodium chloride content in dairy products must be monitored and not exceed the limits defined by the respective public health authorities. The chloride content in food correlates with the salt content, its determination is therefore described in various norms and standards. However, preparation of such samples is time consuming, as it includes a chloride extraction with warm water. Whole milk powders in particular are difficult to handle as an inhomogeneous dispersion of fat in the titration suspension occurs.In order to reduce the workload, increase sample throughput, and eliminate the matrix challenges posed by high fat products, this Application Note presents a fully automatic potentiometric titration of chloride with silver nitrate in milk and milk powder based on ISO 21422, IDF 242, AOAC 2015.07, AOAC 2015.08 and AOAC 2016.03

The salt content in food is a critical parameter, given that the WHO recommends a maximum daily intake of 5 g for an adult. In butter with a salt content exceeding 0.1%, it can be determined by a precipitation titration of chloride with silver nitrate. However, during manual titration the operator cannot leave the system unattended because he has to exchange the sample beakers manually which is time consuming and prone to errors.This Application Note describes the automated determination of chloride in salted butter in accordance with ISO 15648, ISO 21422, IDF 179 and IDF 242. If automated according to the norms and standards, salt determination can be performed completely unattended with superior reproducibility of results increasing efficiency in the laboratory.

The WHO recommends a maximum daily intake of 5 g salt for an adult. The chloride content in food correlates with the salt content, its determination is therefore described by various standards. In cheese and cheese products with a chloride content higher than 0.2%, chloride is usually determined by a precipitation titration with silver nitrate. However, time-consuming sample preparation is required, as the cheese has to be homogenized and the chloride extracted with hot water.This Application Note describes the fully automatic determination of chloride in cheese according to EN ISO 5943, ISO 21422, IDF 242 and IDF 88 including sample preparation with a Polytron homogenizer. This increases productivity due to a higher sample throughput and lower work load for the operator.

The epoxy content of epoxy resins has a strong influence on the reactivity of the resins as well as on the properties of the coating obtained from the resin curing process. The epoxy content is thus an important quality control parameter for manufacturers as well as consumers. This analysis is based on the reaction of hydrogen bromide with the epoxy groups of the sample. Hydrogen bromide in turn is produced by the reaction of tetraethylammonium bromide (TEABr) with standardized perchloric acid. The standards EN ISO 3001 and ASTM D1652 describe the determination of the epoxy content expressed as epoxy equivalent weight (EEW) by titration. The use of a Titrando and Solvotrode easyClean instead of manual titration greatly increases the reproducibility and repeatability of the determination.

In accordance with the European Pharmacopoeia, sodium sulfate is determined with the PB ISE.

Inorganic sulfate is determined in secondary alklysulfonate (raw material) in accordance with DIN EN 14880 with the use of the Pb ISE.

Barium acetate is used as titrant for conductometric sulfate determination. It can be standardized with desiccated sodium sulfate.

Lead is determined at pH 4 to 5 using back titration with zinc sulfate. Xylenol orange is used as an indicator for visualization of the equivalence point. The equivalence point is detected with the Optrode at a wavelength of 574 mm.

Manganese is determined as Mn(II) in aqueous solutions at pH 10 with Eriochrome Black T as indicator. Ascorbic acid is added to ensure that manganese is present in its bivalent form. The precipitation of water-insoluble manganese hydroxide is prevented by adding triethanolamine (TEA). The Optrode is used for detection at a wavelength of 610 nm.

Barium is analyzed in alkali media using direct titration with EDTA. Phthalein purple is used as the indicator; the equivalence point is determined with the Optrode at a wavelength of 574 nm.

Cobalt is analyzed in aqueous solutions using direct titration with EDTA at a pH value of 9. The indicator is murexide. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

Mercury can be determined in alkali media using back titration with zinc sulfate. Eriochrome black T is used as the indicator for this procedure. The Optrode is used for indication at a wavelength of 502 nm.

Palladium is determined at a pH value of 4 to 5 using back titration with zinc sulfate. Xylenol orange is used as the indicator for visualization of the endpoint. The equivalence point is determined with the Optrode at a wavelength of 610 nm.

Tin with EDTA forms very stable complexes in its divalent and tetravalent forms. Hydroxo complexes form in alkali media, which is also why tin is titrated in an acidic medium (pH 2.1). Xylenol orange is used as the indicator. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

Thallium is titrated in slightly acidic medium as Tl(III). Xylenol orange is used as the indicator to determine the endpoint. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

Zirconium is titrated directly with EDTA in acidic aqueous solution (buffer, pH 1). Eriochrome cyanine R is used as the indicator for this procedure. The equivalence point is determined with the Optrode at a wavelength of 520 nm.

Thorium is titrated with EDTA at a pH value of 4.9. Xylenol orange is used as the indicator for visualization of the equivalence point. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

Nickel analysis can be carried out conveniently in alkali media using photometric titration. Murexide is used as the indicator for visualization of the endpoint. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

This Application Note describes the nonaqueous acid-base titration of ketoconazole in accordance with the European Pharmacopoeia. The Solvotrode easyClean was used as the electrode.