Photo-induced chemical vapour generation with formic acid: novel interface for high performance liquid chromatography-atomic fluorescence spectrometry hyphenated system and application in speciation of mercury

Based on a novel photo-induced chemical vapour generation (CVG) with formic acid instead of the conventional K2S2O8/KBH4 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 Hg2+ 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 K2S2O8/KBH4 system were obtained. The limits of detection at the optimized conditions were 0.81, 0.20 and 0.87 mg L-1 for MeHg, 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.