The online coupling of high performance liquid chromatography with atomic fluorescence spectrometry based on dielectric barrier discharge induced chemical vapor generation for the speciation of mercury

Abstract

Based on a novel green dielectric barrier discharge plasma induced chemical vapor generation (DBD plasma-CVG), an on-line hyphenation of high performance liquid chromatography (HPLC) with atomic fluorescence spectrometry (AFS) was developed for the speciation of inorganic mercury (Hg²⁺), methylmercury (MeHg) and ethylmercury (EtHg). Without the use of other chemical reagents, the decomposition of organic mercury species and the reduction of Hg²⁺ could be completed in one step with the DBD plasma-CVG system. The operating parameters of DBD plasma-CVG and HPLC were optimized. Separation of mercury species was accomplished in less than 14 min on a ZORBAX SB-C18 separation column with a mobile phase containing 0.01% (v/v) 2-mercaptoethanol, 10% (v/v) methanol and 0.06 mol L⁻¹ NH₄Ac at pH 6.8. The limits of detection of the method were found to be 1.6, 0.42 and 0.75 μg L⁻¹ for Hg²⁺, MeHg and EtHg, respectively. The developed method was validated by determination of the main analytical figures of merit and applied to the analysis of the certified reference material GBW10029 (tuna fish). The on-line interfacing of HPLC with DBD plasma-CVG-AFS for the speciation of mercury is simple, environmentally friendly, and represents an attractive alternative to the conventional tetrahydroborate interface system.