scope:

This International Standard specifies two methods for the determination of mercury in drinking, surface, ground, rain and waste water after appropriate pre-digestion. For the first method described in Clause 6, an enrichment step by amalgamation of the Hg on e.g. a gold/platinum adsorber is used. For the method given in Clause 7, the enrichment step is omitted. The choice of method depends on the equipment available, the matrix and the concentration range of interest. Both methods are suitable for the determination of mercury in water. The method with enrichment (see Clause 6) has commonly a practical working range from 0,03 ìg/l to 1 ìg/l. The mean limit of quantification (LOQ) reported by the participants of the validation trial (see Annex A) was 0,017 ìg/l. This information can be used as a clue. The method without enrichment (see Clause 7) has commonly a practical working range starting at 0,05 ìg/l. The mean limit of quantification (LOQ) reported by the participants of the validation trial (see Annex A) was 0,024 ìg/l. It is up to the user and the specific application to decide whether higher concentrations should be determined by omitting the enrichment step and/or by diluting the sample(s). The sensitivity of both methods is dependent on the selected operating conditions. Another possibility for the determination of extremely low Hg concentrations down to 0,002 ìg/l without pre-concentration is the application of atomic fluorescence spectrometry (see ISO 17852). Specific Atomic Absorption Mercury Analysers allow determinations down to 0,010 ìg/l without pre-concentration. In general the determination of trace concentrations of Hg by AAS (or AFS respectively) is dependent on clean operating conditions in the laboratory and on high purity chemicals with negligible low Hg blanks. NOTE This International Standard may be applied to industrial and municipal waste water after an additional digestion step under appropriate conditions and after suitable method validation (see 7.4). A potential sample stability issue (mercury loss) for anaerobe reducing industrial effluents has to be considered thoroughly.