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It has been known for years that consuming too much nitrates from foodstuffs can result in cyanosis, particularly for small children and susceptible adults. According to the WHO standard, the hazard level lies at a mass concentration c(NO3-) ≥ 50 mg/L. However, more recent studies have shown that when nitrate concentrations in the human body are too high, they can (via nitrite) result in the formation of carcinogenic and even more hazardous nitrosamines.Known photometric methods for the determination of the nitrate anion are time-consuming and prone to a wide range of interferences. With nitrate analysis continually increasing in importance, the demand for a selective, rapid, and relatively accurate method has also increased. Such a method is described in this Application Bulletin. The Appendix contains a cselection of application examples where nitrate concentrations have been determined in water samples, soil extracts, fertilizers, vegetables, and beverages.

Determination of strontium and barium in monoethylene glycol using cation chromatography with direct conductivity detection.

Determination of sodium, potassium, iron(II), magnesium and calcium in antifreeze (monoethylene glycol) using cation chromatography with direct conductivity detection. Ascorbic acid reduces iron(III) to iron(II). In this way total iron is determined as iron(II).

This Application Note describes the determination of N,N-diethylhydroxylamine (DEHA), triisopropanolamine (TIPA) and a cationic color developing component (CDC) in a developer solution. The analysis is performed on a high-capacity column such as Metrosep C - 250/4.0 with subsequent direct conductivity detection. To reduce the residence time of the strongly retained color developer components, the column flow rate is increased after the elution of the amines.

2-amino-N-(2,2,2-trifluoroethyl)-acetamide is a organic building block for synthesis of pharmaceutical products. Its purity is crucial for the success of the respective synthesis step. 2,2,2-trifluoroethylamine, glycine, and inorganic cations are of interest. Their total peak area is required to be < 2 % of the peak area of all peaks above the reporting level. Separation and quantification is achieved on a Metrosep C 4 - 250/4.0 cation column.

Hydrogen peroxide is available in different purity grades depending on its use. High purity H2O2 (electronic grade) requires very low contamination levels, e.g., less than 1 μg/L of trimethylamine (TMA). This application describes the determination of trimethylamine in a high-purity H2O2 solution (30%). Analysis is performed using Inline Preconcentration with Matrix Elimination (MiPCT-ME) applying conductivity detection after sequential cation suppression.

Determination of bromide and chloride in photographic developer solutions.

Weak, organic bases that are soluble in nonaqueous solvents (including nonpolar solvents) are determined in glacial acetic acid using titration with strong acids, e. g., anhydrous perchloric acid or trifluoromethanesulfonic acid. The endpoint of such titrations can be determined thermometrically, insofar as a suitable thermometric endpoint indicator exists. The exceptional suitability of isobutyl vinyl ether (IBVE) as indicator has been demonstrated.

Lucigenin is one of the most often used chemiluminescent reagents and might be used for e.g., the indication of the presence of superoxide anion radicals.Lucigenin is rather expensive to buy, however, its synthesis only includes a two stage synthesis starting from acridanone. The first stage includes an Nmethylation, the second forms the lucigenin chloride, which is finally transformed into lucigenin nitrate. To check the purity of the synthesized lucigenin, ion measurement can be applied using a nitrate selective electrode. This is a fast and inexpensive method compared to competing methods such as ion chromatography.

The water content of 2-methyl-5-mercaptothiadiazole is determined according to Karl Fischer using a special solvent mixture to prevent unwanted side reactions.