Cryofocusing coupled to atomic absorption spectrometry for rapid and simple mercury speciation in environmental matrices
Résumé
A fully automated on-line hyphenated system for mercury speciation analysis in environmental samples is presented. It provides derivatization by hydride generation or ethylation, preconcentration by cryotrapping, separation by packed column gas chromatography and detection by quartz furnace atomic absorption spectrometry. Automation of the hyphenation results in improved reproducibility of the analysis. The system has been specifically optimised for analysis of mercury compounds, but it is also potentially operative for other hydride- or ethylated derivative-forming elements, after the corresponding optimisation. Main advantages and potential limitations of the system are discussed. General procedures for the analysis of both solid (sediments, biotissues, suspended particulate matter) and liquid (sea and fresh water) samples are proposed and validated by analysis of certified reference materials. The obtained methylmercury and inorganic mercury concentrations are in agreement with the certified values. Detection limits of the method have been estimated as 0.5 ng g-1, 3 ng g-1, 0.1 ng I-1 for both mercury species in dry sediments, biological tissues and aqueous samples, respectively. Analysis of one sample only requires 10 min (hydride generation) or 20 min (ethylation), so that a sample throughout of 6 or 3 samples h-1, respectively, may be achieved. Results from the analysis of real samples collected in the Gironde and Scheldt estuaries (sediments, suspended particulate matter, water and biological tissues) are also provided.