Total Mercury see also Part V, Chapter

Determination of Total Mercury (see also Part V, Chapter 2) 

Earlier methods used to determine mercury in biological tissue and fluids were mainly colorimetric, using dithizone as the com-plexing agent. However, during the past two to three decades, AAS methods - predominantly the cold vapor principle with atomic absorption or atomic fluorescence detection - have become widely used due to their simplicity, sensitivity, and relatively low price. Neutron activation analysis (NAA), either in the instrumental or radiochemical mode, is still frequently used where nuclear reactors are available. Inductively coupled plasma mass spectrometry (ICP-MS) has become a valuable tool in mercury speciation. Gas and liquid chromatography, coupled with various detectors have also gained much importance for separa-tion/detection of mercury compounds (Table 17.1). 

The reduction-aeration (often with included pre-concentration on noble metals) procedures are easy to perform, rapid, selective, and accurate by comparison with many other techniques, and thus are still almost exclusively used particularly in routine toxicological and environmental analysis (Schaller 1985, 2003, Ewers 2003, Welz and Sperling 1999, pp. 675-676). 

Numerous variants of this technique have been published in the literature, and a number of manufacturers tvorldtvide have automated the measurement steps. In recent years, solid sampling CV-AAS has been increasingly used for the determination of total Hg in solid and liquid samples. US EPA method 7473 (1998) is based on this principle, and automated thermal processing instruments are now available from a few instrument producers (Roos-Barra-clough et al. 2002). CV-AAS procedures based on flow injection have also been developed and are in routine use (Murphy et al. 

This method has become increasingly popular in recent years (Watras and Huckabee 

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