The method describes how to determine the content of tetrachloroethene and trichloroethene in drinking water through extraction and gas chromatography.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
As is the case with drinking water, water employed for the production of beer and soft drinks must be neutral in odor and taste.
beer, beer-based beverages, non-alcoholic beverages, mineral water
A qualitative test is performed after shaking the water in a sealed, odor-neutral bottle. Water possessing an odor is measured quantitatively on the basis of a sensory threshold. Water possessing an odor is diluted with odorless water until the odor is barely perceptible (by at least three people). The ratio of the total volume (water with odor + odorless water) to the volume of the mixture containing the water sample is designated as the odor threshold. The taste test should always be performed after evaluating the odor, since the perception of odor can be influenced by flavor.
This method describes how to determine the sulfate content in water by cation exchange.
A water sample is run through an ion exchanger in which all of the cations are replaced with hydrogen ions. The sulfate is determined through titration in the presence of a previously prepared barium chloride solution, of which a known amount in excess of that required is added in advance. The quantity is measured by complexometric titration. The difference between the initial concentration of barium chloride and the amount determined by back titration corresponds to the sulfate content.
In many cases, particularly at higher contents, an alternative and sufficiently accurate measurement is possible, called the “negative m value” or the “total mineral acid value” (without carbonic acid). This is achieved through titration. Subsequently, the mval values for the anions (Cl-, NO3-, NO2-, PO43-) are subtracted from the result.
The method describes how to determine the chloride content in water by means of the analytical method according to MOHR.
Transformation of the chloride ions in the presence of silver ions produces silver chloride, which is not very soluble, until all the chloride ions are bound. The excess silver ions react with chromate ions to silver chromate, which exhibits a reddish brown color:
Cl - + Ag+ → AgCI
2 Ag+ + CrO42- → Ag2CrO4
The method describes how to determine the chlorine dioxide content of water photometrically with a cuvette test.
Transformation of chloride solutions in the presence of mercury thiocyanate produces less-dissociated mercury(I) chloride. An equivalent quantity of thiocyanate ions is released simultaneously, forming iron(III) thiocyanate with iron(III) salts. The red hue resulting from the reaction is determined photometrically.
The method describes how to determine the free and total chlorine content using a titrimetric method with DPD.
The analysis involves a reaction with N,N-diethyl-1,4-phenylenediamine (DPD), which forms a compound possessing a red color at a pH of 6.2–6.5. The solution is titrated with an ammonium iron(II) sulfate standard solution until the red color disappears. Total chlorine is measured through the addition of potassium iodide, of which a known amount in excess of that required is added to the solution in advance.