Mercury Assay by Cold Vapor Atomic Absorption Spectrometry

The most widely used method for the determination of total mercury is cold vapor atomic absorption spectrometry (CV-AAS), based on a technique elaborated in detail by Hatch and Ott (Anal. Chem., 1968, 40, 2085-87). In this method, (divalent) ionic mercury is reduced to its metallic form (Hg^o) in acidic solution using a powerful reducing agent. Subsequently, the elemental mercury is volatilized (purged) by a carrier gas and transported into an absorption cell, where the 253.65 nm wavelength absorbance of mercury atoms is measured.

CV-AAS analysis can be performed manually using batch CV-AAS or automatically using sequential injection (SI) techniques. SI is a very efficient approach for introducing and processing liquid samples in atomic absorption spectrometry. The SI technique, combined with a built-in atomic absorption spectrometer optimized for mercury determination, reduces sample and reagent consumption, has a higher tolerance of interference's, lower determination limits and improved precision compared with conventional cold vapor techniques.