Glow discharge atomic emission spectrometry as a detector in gas chromatography for mercury speciation

Abstract

The analytical potential of radiofrequency (rf) and direct current (dc) glow discharges (GD), with atomic emission spectrometry (AES), as detectors in capillary gas chromatography (GC) is investigated for the speciation of low levels of mercury (methylmercury, ethylmercury and inorganic mercury). The design of the interface between the GC and the GDs is discussed and the effect of the operating parameters on the analyte signals is studied for both types of GDs. The figures of merit obtained with both GC–GD–AES systems (rf and dc) are presented. The detection limits, for 1 µl sample injections, were found to be 1.3, 1.3 and 3.0 ng ml^–1 of methylmercury, ethylmercury and inorganic mercury, respectively. The reproducibility was below ±7% for the three species. The coupling of GC to dc-GD-AES was applied successfully to the determination of methylmercury in fish tissue certified reference material after extraction with sodium diethyldithiocarbamate and Grignard derivatization.