ION-CHROMATOGRAPHIC SEPARATION AND ONLINE COLD VAPOR ATOMIC-ABSORPTION SPECTROMETRIC DETERMINATION OF METHYLMERCURY, ETHYLMERCURY AND INORGANIC MERCURY

The ion chromatographic separation of methylmercury, ethylmercury and inorganic mercury as cysteine complexes was investigated. The chromato graphic apparatus was interfaced with cold vapour atomic absorption sp ectrometry for detection using an on-line continuous flow cell coupled with a reduction system (sodium tetrahydroborate). The influence of t he composition of the eluent (pH, ionic strength, cysteine concentrati on) and stripping gas flow-rate was investigated. The method was optim ized by coupling an on-line preconcentration step. The detection limit s, evaluated on 100.0-ml samples, were 2, 10 and 4 ng for Hg, CH3Hg an d C2H5Hg, respectively. The method was applied to synthetic mixtures a nd natural samples (tap water) and furnished satisfactory results.