Determination of ultra-trace mercury in water samples based on cold vapor atomic fluorescence spectrometry using a gold trap

Abstract

This paper presents a method for mercury determination in water samples, at trace level using Cold Vapor Atomic Fluorescence Spectrometry (CVAFS). Mono, divalent mercury and organo-mercury compounds are converted to divalent mercury by oxidation with KbrO3-KBr in hydrochloric acid, as a result of Br and BrCl reaction. Before the analyses, the excess of Br is removed by ascorbic acid. The divalent mercury is then reduced to the elemental form using 20 g/L tin chloride in acid medium, purged with argon in a hygroscopic membrane in order to retain humidity and then withhold on a gold trap. Gold trap is used to concentrate Hg vapor prior to detection. After heating the trap, mercury is detected using an ozone-free Hg lamp. The analytical performance parameters of the method have been investigated (detection limit, quatification limit, working range, precision, recovery). The method is suitable for determination of ultra-trace mercury content from drinking, surface and wastewater samples.