Direct chemical vapour generation-flame atomization as interface of high performance liquid chromatography-atomic fluorescence spectrometry for speciation of mercury without using post-column digestion

Abstract

A high performance liquid chromatography-direct chemical vapour generation-flame atomization-atomic fluorescence spectrometry (HPLC-CVG-FA-AFS) system for speciation of methylmercury (MeHg⁺), inorganic mercury (Hg²⁺) and ethylmercury (EtHg⁺) without using post-column digestion is developed and characterized. In this novel system, organomercurial species separated by chromatography were transformed to their hydrides by KBH₄, further atomized in the flame atomizer and detected by AFS. The conventionally used on-line UV or microwave digestion system was omitted, and no oxidation reagent was needed, which significantly simplified the instrumentation. Under the optimized conditions, the detection limits were 0.2, 0.4 and 0.4 µg L⁻¹ (as Hg) for MeHg⁺, Hg²⁺, and EtHg⁺ (100 µL injection), which corresponds to absolute detection limits of 0.02, 0.04 and 0.04 ng (as Hg) for MeHg⁺, Hg²⁺, and EtHg⁺, respectively. The sensitivity of the developed method was comparable with the conventional high performance liquid chromatography-UV digestion-cold vapour generation-atomic fluorescence spectrometry (HPLC-UV-CVG-AFS) system. Validation with biological certified reference materials showed that the proposed method is simple and accurate for mercury speciation.