Cold vapour atomic absorption and fluorescence methods for mercury

5 Cold vapour atomic absorption and fluorescence methods for mercury 

The most common technique for the determination of mercury in environmental samples is cold vapour atomic absorption spectrometry (CV-AAS) due to its simplicity and sensitivity. The flameless procedure was investigated by Hatch and Ott (1968) with a view to simplifying the apparatus required and improving the sensitivity of the method. The method is based on the unique properties of mercury. Elemental mercury has an appreciable vapour pressure at ambient temperature and the vapour is stable and monatomic. Mercury can easily be reduced to metal from its compounds. The mercury vapour may be introduced into a stream of an inert gas and measured by atomic absorption or atomic fluorescence of the cold vapour without the need of atomiser devices. 

Inorganic mercury Hg(II) is usually reduced to metallic mercury by tin(II) chloride (SnCl2), or sodium borohydride, then the reduced elemental mercury is liberated and swept to the absorption or fluorescence cell by the circulating inert gas. 

Limits of detection are based on three times the standard deviation of the blank. 

The detection limit for mercury is sometimes limited by background laboratory contamination rather than the actual detection method. 

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