Fe3+-catalyzed degradation of organic mercury as a simple post-column interface for the speciation of mercury by high-performance liquid chromatography-catalytic cold vapor-atomic fluorescence spectrometry

Abstract

A novel and simple interface used in a high-performance liquid chromatography-catalytic cold vapor-atomic fluorescence spectrometry (HPLC-CCV-AFS) hyphenated system without post-column digestion, based on the catalytic degradation of organic mercury by directly introducing Fe³⁺ into the carrier, was developed for the speciation of mercury. The synergy of Fe³⁺ with L-cysteine or mercaptoethanol reduces the Fe³⁺ concentration. The parameters influencing mercury separation and determination were optimized, including the content of Fe³⁺ in the carrier, the concentration of L-cysteine, KBH₄ and HCl, and the flow rate of the carrier gas and shielding gas. Under the optimized conditions, the limits of detection (LODs) for monomethylmercury (MeHg), ethylmercury (EtHg) and Hg²⁺ (IHg), based on a 100 μL sample, were 0.06, 0.09, and 0.13 μg L⁻¹, while the LODs of MeHg, EtHg and IHg in food samples, based on 0.2 g sample and 50 mL final sample volume, were 15, 23 and 33 μg kg⁻¹, respectively. The proposed method with a simple interface, high sensitivity, low instrument and operation cost, easy operation, reduced damage to the instrument pipeline and reduced use of harmful and organic reagents was successfully applied to fish samples and is suitable for routine use.