Simultaneous determination of mercury and arsenic species in natural freshwater by liquid chromatography with on-line UV irradiation, generation of hydrides and cold vapor and tandem atomic fluorescence detection

An approach based on the coupling HPLC–UV–CV/HG–mAFS–AFS has been developed for the simultaneous determination of mercury and arsenic species. A home modified AFS detector has been used for the analysis of mercury coupled in series with another similar detector for arsenic determination. The determined species were Hg2+, methylmercury (MeHg+), As(III), As(V) and monomethylarsinate (MMA). A critical aspect is the chromatographic separation, which was carefully optimized for the separation of all the species. The detection limits for these species are 11, 8, 17, 17 and 3 ng ml−1, respectively. Linear curves for MMA were obtained between 10 and 200 ng ml−1. The linear dynamic range for all the other species was comprised between the detection limit and 500 ng ml−1. The influence of cations and anions at the concentration usually present in natural freshwater was studied. The procedure was validated by application to spiked natural freshwater samples from the south-west Spain, and it can be considered for routine analysis of polluted sites.