Applicability of multisyringe chromatography coupled to cold-vapor atomic fluorescence spectrometry for mercury speciation analysis

In this paper, a novel automatic approach for the speciation of inorganic mercury (Hg2+), methylmercury (MeHg+) and ethylmercury (EtHg+) using multisyringe chromatography (MSC) coupled to cold-vapor atomic fluorescence spectrometry (CV/AFS) was developed. For the first time, the separation of mercury species was accomplished on a RP C18 monolithic column using a multi-isocratic elution program. The elution protocol involved the use of 0.005% 2-mercapthoethanol in 240 mM ammonium acetate (pH 6)–acetonitrile (99:1, v/v), followed by 0.005% 2-mercapthoethanol in 240 mM ammonium acetate (pH 6)–acetonitrile (90:10, v/v). The eluted mercury species were then oxidized under post-column UV radiation and reduced using tin(II) chloride in an acidic medium. Subsequently, the generated mercury metal were separated from the reaction mixture and further atomized in the flame atomizer and detected by AFS. Under the optimized experimental conditions, the limits of detection (3σ) were found to be 0.03, 0.11 and 0.09 μg L−1 for MeHg+, Hg2+ and EtHg+, respectively. The relative standard deviation (RSD, n = 6) of the peak height for 3, 6 and 3 μg L−1 of MeHg+, Hg2+ and EtHg+ (as Hg) ranged from 2.4 to 4.0%. Compared with the conventional HPLC–CV/AFS hyphenated systems, the proposed MSC–CV/AFS system permitted a higher sampling frequency and low instrumental and operational costs. The developed method was validated by the determination of a certified reference material DORM-2 (dogfish muscle), and was further applied for the determination of mercury species environmental and biological samples.

Graphical abstractAn automatic system, based on the applicability of multisyringe chromatography (MSC) coupled to cold-vapor atomic fluorescence spectrometry (CV/AFS) detection is developed for mercury speciation.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The on-line coupling of MSC to CV/AFS was developed for mercury speciation analysis. ► The speciation of MeHg+, Hg2+ and EtHg+ was achieved on a RP C18 monolithic column. ► The hyphenated system provided higher sample throughput compared to HPLC–CV/AFS. ► The limits of detection for mercury species were comparable or better than those reported by HPLC–CV/AFS. ► The developed method also provided low instrumental and operational costs.