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Standardless Analysis of Hg With the Cold Vapor Method: Evaluation of the Best Use of Modern Instrumentation

Volume 56, Number 7 (July 2002) Page 859-862

Vecchiati, Giorgio; Fagioli, Francesco; Torsi, Giancarlo; Locatelli, Clinio; Mazzotta, Dionisio; Pagnoni, Antonella

The so-called cold vapor method is extensively used in atomic absorption spectroscopy for the quantitation of Hg and hydride forming elements. In the case of Hg it is possible to take advantage of the standardless method of analysis (which gives a quantitative result from a single measurement) if a stannous salt is used as a reducing agent. This type of analysis, which has the advantages of high sensitivity, low analysis time, and easy checking of the perfect working conditions of all the components of the apparatus, can be made with very slightly altered commercial instruments if flowmeters of good accuracy and precision are used. The mode of operation of modern commercial instruments can be either discontinuous, with a chromatographic-like injector, or continuous. A survey of the instruction manuals shows that virtually all manufacturers prefer the discontinuous mode. Our experimental results demonstrate that only with the continuous mode, if sufficient sample volume is available, is it possible to use the standardless method of analysis.