The method describes how to determine the nitrate content of water photometrically with a cuvette test.
In an acidic sulfurous solution containing phosphorus, nitrate ions react with 2,6-dimethylphenol to produce 4-nitro-2,6-dimethylphenol.
The method is suitable for determining approx. 0.5–25 mg/l NO3-. If the ratio of chloride to nitrate ions is larger than 10, this may interfere with the reaction (if this is the case, according to DEV D 9-3, follow DIN 38405); likewise, nitrite ions exceeding approx. 0.2 mg/l may also interfere with the reaction. For their removal, refer to Remarks below.
The method describes how to determine the anion content of water by means of ion chromatography.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
Separation using ion chromatography and subsequent conductivity detection (of other anions as well)
Determination of the concentration of the anions bromide, chloride, fluoride, nitrate, nitrite, oxalate, phosphate and sulfate through ion chromatography
Water, wort, beer, NAB and beverages as well as malt and hops
Separation of bromide, chloride, fluoride, nitrate, nitrite, oxalate, phosphate and sulfate through ion chromatography followed by conductivity detection
Determination of the nitrate content of wort, beer and other beverages as well as that of malt and hops.
This method is suitable for wort, beer and other beverages as well as for malt and hops.
Essentially, the nitrate content of beer originates with the nitrate derived from the brewing liquor and the hops (whole hops, hop powder). Nitrate is reduced to nitrite by yeast has not been found to occur at any stage in the brewing process.
Nitrate is reduced with reduced nicotinamide adenine dinucleotide phosphate (NADPH) to nitrite in the presence of the enzyme nitrate reductase (NR) [1].
Nitrate + NADPH + H+ \(^{\underrightarrow{NR}}\) nitrite + NADP+ + H2O
The quantity of NADPH consumed in this reaction is proportional to the amount of nitrate in the sample. NADPH is measured and the determination is performed at 334, 340 oder 365 nm, due to its absorption at these wavelengths.
This method is suitable for the determination of anions (chloride, sulfate, nitrate, phosphate) in beer samples and other beverages by means of ion chromatography.
The anions chloride, sulfate, nitrate and phosphate are separated by means of ion chromatography. The conductivity detection with a suppressor provides quantitative information about the anions. The concentrations are calculated by means of the individual areas under the peaks from the chromatogram with reference to calibration factors.