Analysis of organomercuric species in soils from orchards and wheat fields by capillary gas chromatography on-line coupled with atomic absorption spectrometry after in situ hydride generation and headspace solid phase microextraction

Abstract

A convenient procedure for the determination of organomercuric compounds in soils from orchards and wheat fields is described based on the aqueous derivatization of the polar organomercuric halides in 0.1 M HAc-NaAc (pH 4) buffer into their hydrides by addition of 1 mL of 6% KBH4 with subsequent headspace solid phase microextraction (SPME) of the volatile derivatives. The volatile derivatives are separated by gas chromatography (GC) with a Supelco SPB-1 capillary column and on-line detected by electric heated quartz furnace atomic absorption spectrometry (AAS). The relative standard deviations for ten replicate measurements are 2.1%, 2.8% and 3.5% for methyl-, ethyl- and phenylmercury with absolute detection limits of 16 ng, 12 ng and 7 ng, respectively. This method is applied to the analysis of organomercuric compounds in soil samples and 0.04–0.64 μg/g of organomercuric species are detected in soils from different sites. The recoveries after standard addition are between 93–106%.