CVAAS spectroscopy

In 2002 extensive kinetic and product studies on the reactions of gaseous Hg with molecular and atomic halogens (X/X2 where X = Cl, Br) were performed at atmospheric pressure (750 1 Torr) and room temperature (298 1 K) in air and N2 [24]. Kinetics of fhe reactions with X/X2 were studied using both relative and absolute techniques. Cold vapour atomic absorption spectroscopy (CVAAS) and gas chromatography with mass spectroscopic detection (GC-MS) were the analytical methods applied. The measured rate constants for the reactions of Hg with CI2, Cl, Br2, and Br were (2.6 0.2) x IQ-i , (1.0 0.2) x 10" , < (0.9 0.2) x and (3.2 0.3) x 10 cm molecule s , respectively. Thus CI2 and Br2 are not important reactants in the troposphere for the CI2 and Br2 concentrations reported in literature [24]. 

The primary method used to analyse for mercury is CVAAS (cold vapour atomic absorption spectroscopy). This has a sensitivity of parts per trillion for urine while determination of mercury in fish, shellfish, pharmaceuticals and foodstuffs has a sensitivity in the low parts per billion range, as has the analysis of mercury in samples of tissues and hair. Mercury levels in newly formed hair reflect those in blood the concentration however is about 250 times greater in hair. Once the mercury has interacted with the sulphur-containing proteins in hair it is essentially "fixed" and so provides an accurate monitor of exposure and accumulation. Analysis of the hair length can therefore be used to estimate the dates of contamination by mercury and also the peak blood levels achieved. 

The method which has demonstrated to be most successful one for mercury determination within natural waters is that called cold vapor-atomic absorption spectroscopy (CVAAS), which can be used with a preconcentration step [337-339] or without it [340-342], In addition, the use of continuous-flow systems for Hg CV generation has also been reported [343-345]. 

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