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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.

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).

Cadmium can be determined in aqueous solutions using back titration with zinc sulfate. Eriochrome black T is used as the indicator for this procedure. The equivalence point is determined with the Optrode at a wavelength of 610 nm.

The alpha acid level (AA%) in hops plays a major role in the bitterness they can impart to beer. The AA% can vary between 1% up to 20% in hops. During boiling in the brewing process, alpha acids transform into iso-alpha acids which make the beer bitter. For this reason, it is important for brewers to know the exact AA value of the hops they use. The determination of AA% in hops with conductometric titration according to the EBC method 7.4 is shown in this Application Note.

Alkyl glycosides, alkyl maltosides and compounds with polyoxyethylene groups (POE) are numbered among the nonionic surfactants. These surfactants can be analyzed by standard titration with TEGO®trant following derivatization – in this case following sulfonation.

The purity of sulfanilamide was determined by means of automatic potentiometric titration using sodium nitrite as the titrant. The solution was spiked with potassium bromide, because bromide ions catalyze diazotization titration.

Gallium is determined at a pH value of 4.7 using back titration with zinc sulfate. 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 610 nm.

The basicity and the CPR (controlled polymerization rate) are very important parameters for the quality of polyols used in polyurethane production. The knowledge of these values is crucial to prevent gelation during handling in the production. In this Application Note their determination by automated, potentiometric titration according to ISO 14899 is described.

Acrylic acid dimerizes spontaneously. Determining the dimer content is, therefore, a key part of the quality control for acrylic acid. One quality control parameter for the dimerization is the acid number. This Application Note describes its determination by automated, potentiometric titration.

The composition of salts with laxative and expectorant effects must be determined precisely in medications. The sulfate content is determined using automatic potentiometric titration with EGTA as titrant in accordance with Ph. Eur. 8.0.

Vitamin C is an important antioxidant and an important component of orange juice. A convenient and precise method for Vitamin C determination in fruit juices is titration, which is also described in numerous standards (ISO 6557/1, ISO 6557/2, AOAC 967.21).OMNIS enables quick and accurate determination of Vitamin C content in orange juice using potentiometric titration with iodine as titrant and a separate double Pt-sheet electrode.

OMNIS is the ideal system for quick and accurate determination of aluminum in aluminum chloride using complexometric back titration with an ion-selective copper electrode (Cu-ISE). Copper sulfate is used as the titrant.

The partial acid number (also partial acid value) describes the quantity of potassium hydroxide that is required for neutralizing all carboxyl-terminated groups and free acids plus half the anhydride groups in an unsaturated polyesterresin (UPR). This Application Note describes the determination of the partial acid value by automatic, potentiometric titration according to EN ISO 2114 using KOH in ethanol as titrant.

The total acid number (TAN) indicates the amount of potassium hydroxide required for neutralizing all carboxyl-terminated groups and free acids plus the free anhydride groups in an unsaturated polyester resin (UPR). In this Application Note the TAN determination using automated, potentiometric titration according to EN ISO 2114 using KOH in ethanol as titrant is described.

The hydroxyl number indicates the amount of potassium hydroxide in milligrams required to neutralize the acetic acid taken up on acetylation of 1 g of an unsaturated polyester resin (UPR) containing free hydroxyl groups. In this Application Note the determination of the hydroxyl number by automated, potentiometric titration according to EN ISO 2554 using KOH in methanol as titrant is described.

Polyurethane (PU) is a class of very important polymers due to its flexibility and insulating properties. It is used in various industries such as the automobile industry, in building construction, as well as in the production of synthetic fibers. PU is mostly produced via a chemical reaction between polyisocyanates and polyols.The isocyanate (NCO) content in the raw material is crucial to control its properties. This Application Note shows an easy and straightforward way to determine the NCO content in polyurethane raw materials using a fully automated titration system from Metrohm.

Complexing agents such as EDTA are used in soaps and other detergents in order to remove unwanted metal ions and to lower water hardness. The EDTA content in soaps and detergents can be determined using potentiometric titration with copper sulfate as titrant and the Cu-ISE as electrode.

Citrate is used in detergents as a water softener for the prevention of lime deposits. The citrate or citric acid content is therefore an important parameter for the quality control of detergents that can be determined conveniently and precisely using titration with copper sulfate.

Nitrilotriacetate (NTA) is a complexing agent that is used in detergents as a water softener. NTA forms complexes with metal ions such as Ca2+, Cu2+ and Fe3+ and thus prevents the formation of lime and its deposits. The NTA content is therefore an important parameter for the quality of detergents and is determined using back titration of an excess of copper nitrate.

Vitamin C is an important antioxidant included in milk powder. The double Auring electrode provides an excellent titration curve when using 2,6-dichlorophenolindophenol (DPIP) as titrant and is easy to clean.With the OMNIS system, a fast and accurate determination of vitamin C in milk powder by a bi-voltametric titration is realized.

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 quantity of hydrolyzable chloride in epoxy resins has an influence on their reactivity and on the properties of the epoxy coating obtained.Rapid and accurate determination is possible with an OMNIS system using potentiometric titration with the dAg ring electrode and silver nitrate as the titrant.

Nicotine is a nitrogenous alkaloid that is hazardous to health and is characterized by a very high potential for addiction. The nicotine content in tobacco products must be determined and specified precisely. This Application Note exhibits an easy and straightforward method for nicotine determination in tobacco by non-aqueous titration.Results determined by GC and IC are given as a comparison. In comparison to chromatographic methods, titration is an «absolute method», meaning it is not necessary to calibrate the system prior to the analyses.

The iodine adsorption number (IAN) of carbon black is related to the surface area and can therefore be used for the characterization of carbon black. The presence of volatiles, surface porosity, or extractables will influence the iodine adsorption number. In this Application Note, the fully automated determination of the iodine adsorption number including sample preparation is described.

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.

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. Unlinke other standards, ASTM E1899 works pyridine-free and without refluxing at elevated temperatures for a longer time. It is performed at room temperature, requires only a small sample size, is applicable to extremely low hydroxyl numbers (<1 mg KOH/g sample) and can be performed fully automatically. This Application Note describes the potentiometric determination of the hydroxyl number in 1-octanol and polyethylene glycol according to ASTM E1899, EN 15168 and DIN 53240-3. Using the OMNIS DIS-Cover technique all sample preparation steps can be fully automated. Moreover, 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 24 min to 12 min., increasing productivity in the laboratory considerably.

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.

Lithium is a soft metal which is used for many applications, such as production of high-temperature lubricants or heat-resistant glass. Furthermore, lithium is used in large quantities in for battery production. It is obtained from brines and high-grade lithium ores. Depending on the lithium concentration, extraction may or may not be economically viable.This Application Note demonstrates a method to determine the lithium concentration in brines by potentiometric titration. Lithium and fluoride precipitate in ethanol as insoluble lithium fluoride. Using ammonium fluoride as the titrant and a fluoride ion-selective electrode (ISE), determination via potentiometric titration is possible. This method is more reliable, faster, and less expensive than the determination of lithium in brine by other more sophisticated techniques such as atomic absorption spectroscopy (AAS).

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.

Metformin is one the most commonly used drugs for diabetes type 2 belonging to the group of biguanides. This Application Note describes the determination of metformin hydrochloride assay according to USP using acetic anhydride as solvent.

Quaternary ammonium salts are the active ingredients in fabric softener and require accurate determination to assess the cost and the performance of the fabric softener. This Application Note describes the determination of diamidoamine-based quaternary ammonium salts by potentiometric titration.

Quaternary ammonium salts are the active ingredients in fabric softener and require accurate determination to assess the cost and the performance of the fabric softener. This Application Note describes the determination of dialkyl dimethyl quaternary ammonium salts by back titration.

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.

The total iron content in iron ore plays a central economic role for mining companies. The higher the iron content in the ore, the more profitable the mining operation. Therefore, a fast and accurate analysis is important to determine the most profitable areas to work.The iron ore is dissolved in hydrochloric acid at 80 °C. Afterwards, the iron is quickly and accurately determined by potentiometric titration using the Pt-ring electrode and potassium dichromate as titrant.

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.

The knowledge of the exact silver content of silver allows used for jewelry is very important to ensure the quality of jewelry. Therefore, the determination procedure is regulated internationally and nationally. A common approach is the titration with potassium bromide after an acidic digestion of the silver using a silver electrode for indication.

This Application Note details the determination of acid-neutralizing capacity (ANC) in several pharmaceutical samples in compliance with USP<301> standards.

Penicillin and its related antibiotics are used to prevent and treat a number of bacterial infections, such as respiratory tract infections, urinary tract infections, meningitis, etc. It may also be used to prevent group B streptococcal infection in newborns. The β-lactam ring of penicillin binds to the enzyme DD- transpeptidase, which prevents the formation of cross links during cell wall formation of new bacterial cell, i.e., the division of bacterial cells. USP<425> describes a back-titration method to determine the assay of pharmacopeial penicillin antibiotic drugs and their dosage forms by iodometric titration. The method is illustrated by determining the aminopenicillin content in an ampicillin capsule.

Sulfonamides are drugs used to treat allergies and cough. They also have some antifungal and antimalarial activities. USP<451> describes nitrite titration method for the determination of numerous pharmacopeial sulfonamide drugs and their dosage forms as well as of other pharmacopeial drugs with, for example, hydrazide (e.g., in isoniazid) and amine ester groups (e.g., in procaine) or amide derivatives of amino acids.Here, for illustrating the analysis of the latter, the assay of the diagnostic agent aminohippuric acid is described.

Kjeldahl method is used to determine the nitrogen content in organic and inorganic samples. Kjeldahl consists of three steps: digestion, distillation, and titration. During the catalytic digestion step, organic nitrogen1 is converted into ammonium. Sodium hydroxide is added just before the distillation step for converting ammonium into ammonia. Through steam distillation the latter is transferred into the receiver vessel containing an absorbing agent (e.g., boric acid). Finally, the separated ammonia is titrated against sulfuric acid. Protein content in samples can also be determined from the nitrogen content obtained by Kjeldahl setup. USP describes the titration method to determine nitrogen content in organic products using Kjeldahl nitrogen setup. This Application Note illustrates nitrogen determination in heparin sodium. ______________________ 1Kjeldahl is not working for all nitrogen-containing compounds; nitro and azo groups and nitrogen in rings are not included.

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.USP general chapter <580> describes a titration technique to determine the assay of Vitamin C as ascorbic acid, sodium ascorbate, and calcium ascorbate dehydrate, or their mixture in finished dosage forms as capsules, tablets, and oral suspensions. This Application Note demonstrates the Vitamin C determination in water-soluble vitamin tablets. The methodology can also be applied for oil-soluble vitamin or mineral tablets, as well as oil- and water-soluble vitamin or mineral capsules.

The surface glass test for hydrolytic resistance combined with the glass grains test determines the glass type. The hydrolytic resistance is determined by the quantity of alkali released from the glass under specified conditions. The released alkali is then titrated with hydrochloric acid to a pH value of 5.5.

Anionic surfactants represent, by volume, the most important group of surfactants used in cleaning products. The potentiometric two-phase titration is a universal method for the accurate and fast determination of them. Using the Surfactrode Refill, the anionic surfactants are determined by potentiometric titration with hyamine as titrant.