Arsenic speciation by cryogenic trap hydride generation atomic absorption spectroscopy: performance enhancement by pre-derivatization

Abstract

A preliminary investigation of a range of sulfur complexants (l-cysteine, 2,3-dimercapto-1-propanol, 2-mercaptoethanol, 3-mercaptopropionic acid, thioglycollic acid and sodium diethyldithiocarbamate) has demonstrated that pre-derivatization of arsenite, arsenate, methylarsonate and dimethylarsinate can result in a significant enhancement of the cryogenic trap hydride generation AAS procedure. The most effective of these reagents is thioglycollic acid. Pre-derivatization of arsenic species with this reagent results in the equalization of arsine yields from arsenite and arsenate and enhances arsine yields from the other arsenic species. Pre-derivatization with thioglycollic acid is more rapid than with cysteine and is therefore better suited to continuous flow pre-derivatization procedures.