Based on a novel photo-induced chemical vapour generation (CVG) with formic acid instead of the conventional K 2 S 2 O 8 /KBH 4 system, an on-line coupled HPLC and atomic fluorescence spectrometry procedure was developed for the speciation of inorganic mercury, methylmercury (MeHg), ethylmercury (EtHg) and phenylmecury (PhHg). Under UV irradiation, the decomposition of organic mercury species and the reduction of Hg 2+ could be completed in one step with this proposed photo-induced CVG system. The novel CVG system used formic acid only, which simplified the flow system and avoided the possibility of contamination originating from additional chemicals. A number of operating parameters including organic acid species, concentration of formic acid, pH, flow rate of formic acid and flow rate of carrier gas were optimized, and comparable method sensitivities with the conventional K 2 S 2 O 8 /KBH 4 system were obtained. The limits of detection at the optimized conditions were 0.81, 0.20 and 0.87 mg L À1 forMeHg, EtHg and PhHg, respectively. The developed method was validated by determination of certified reference material DORM-2 and was further applied in determination of seafood samples. The new CVG system is simple, environmentally benign, and inexpensive for the speciation analysis of mercury. It is expected to have similar applications in other analytical atomic spectrometric techniques as well as speciation of other organic metal compounds.
Abstract. Three extraction systems including shaking, ultrasonic and microwave-assisted extraction were evaluated. Water and phosphate buffer were tested for the extraction of arsenic compounds in polluted soil, describing the water-soluble or plant-available fraction. The stabilities and recoveries of various arsenic species indicated that no obvious changes of species occurred during the extraction process. The raw extracts were cleaned up by C 18 cartridge before analysis. Having optimized the extraction conditions, the arsenic species in polluted soil and ore from the different pollution sources were extracted by microwave-assisted extraction with 0.5 M phosphate buffer as extractant. Arsenic species were quantitatively determined by high performance liquidchromatographyon-line coupledwith hydridegeneration atomic fluorescence spectrometry (HPLC-HG-AFS). As(III) and As(V) were the major arsenic species in the polluted soil samples resulting from irrigation by waste water. As V was the only form found in the rotten ore sampled in mining area. During the extraction process, the recoveries of spiked As(III), As(V), DMA(V) and MMA(V) were 85.4 AE 7.2%, 80.2 AE 6.7%, 101.6 AE 6.7% and 98.8 AE 9.1%, respectively, showing that most water-soluble arsenic could be measured.
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