Determination of methylmercury using liquid chromatography – photochemical vapour generation – atomic fluorescence spectroscopy (LC-PVG-AFS): a simple, green analytical method

Abstract

Reliable, fast and cost efficient mercury analysis is paramount to assess Hg levels in a huge variety of matrices, from soil and water to a variety of foodstuffs. In this work, a novel concept was adopted for seafood and hair analysis, which combines a simplified methylmercury extraction and photochemical vapour generation of Hg⁰ with liquid chromatography and atomic fluorescence spectrometry (LC-AFS). This concept reduces the number of reagents required to methanol and APDC for extraction and separation of Hg species, and acetic acid, which when combined with UV generates volatile Hg⁰ in one single step. Here, we compare conventional chemical vapour generation (CVG) with photochemical vapour generation (PVG) for seafood and hair matrix. Our results show that the LC-PVG-AFS method offers lower detection limits and higher precision than that of LC-CVG-AFS measurements by a factor of two. The extraction and LC-PVG-AFS technique was validated using 7 seafood and hair reference materials, yielding methylmercury recoveries of 93.2% to 105%. Further validation was carried out by comparing results from methylmercury determination in 14 tuna samples by the LC-PVG-AFS method to results obtained by GC-AFS, showing R² = 0.98 and a gradient of 1.0077, which indicates good correlation between the newly developed LC-PVG-AFS technique to an already validated GC-AFS method.