Mercury determination in natural, surface, sea, drinking, bottled, mineral, and waste water by cvaas
Mercury determination in natural, drinking, and waste waters is one of the most popular analyses used for environment pollution and sanitary control. Background concentrations of mercury in natural water are within several ng/l. Maximum national permissible levels for mercury in water lie in the range of 0.16–6 µg/l. For example, the following limits for mercury in drinking water are set, µg/l:
0.5 – Japan, Russia;
1 – Argentina, Australia, Brazil, China, EC;
2 – US EPA, US FDA;
6 – WHO.
The measurement method is based on standard procedures of digestion of mercury compounds in a water sample, reduction of mercury cations from decomposed sample with a tin chloride solution in the reaction vessel of RP-92 attachment (“cold vapor” technique) and further determination of atomic mercury using the method of atomic absorption with the RА-915М analyzer (using single-path and multi-path cells).
Depending on the chemical composition of a sample, one of the following two methods of digestion should be used. Method А (permanganate digestion) is recommended for preparation of samples with a complex matrix. This method is used to analyze natural, potable, and waste water. Method B (bromide-bromate digestion) suggests softer digestion conditions and is used to prepare samples of natural water (including seawater), mineral, potable water (including bottled and packaged water), and purified waste water.
The method of LUMEX Instruments allows one to determine both total mercury content and dissolved forms of mercury. Approximate time of sample preparation for analysis is 30 minutes for Method B and 2 hours for Method A. Limit of detection 0.5–2.5 ng/l depends on the purity of reagents. The measurement ranges of the mass concentration of total or dissolved mercury are 0.010–2000 µg/l (Method A); 0.010–50 µg/l (Method B).
The time of mercury concentration measurement does not exceed 2 minutes.