Winter Plasma (EWCPS) 2019

POSTER - PP102 - Determination of Methylmercury using Liquid Chromatography - Photochemical vapour generation - Atomic Fluorescence Spectroscopy LC-PVG-AFS

Authors: Shaun, T. Lancaster and Dr Warren T Corns (PSA) and Jorg Feldmann and Eva, M. Krupp (University of Aberdeen)

A reliable method for the analysis of mercury species is cold vapour generation of mercury coupled with atomic fluorescence spectrometry (AFS) or inductively coupled plasma – mass spectrometry (ICP-MS). The most commonly used method of cold vapour generation involves oxidising all organic mercury species to inorganic mercury (Hg2+), followed by a reduction to elemental mercury (Hg0) with tin(II) chloride or sodium borohydride. However, this method uses a plethora of chemicals which is costly and prone to error, as well as instrumental issues due to the complex wet chemistry necessary.

Another pathway is photochemical vapour generation (PVG), which has been used in the past in conjunction with AFS and ICP-MS as an alternative method of cold vapour generation. PVG has previously been applied to total mercury measurements using UV with formic acid and acetic acid. PVG promises a much simpler and more cost effective approach with fewer and more environmentally friendly chemicals, achieving results that are comparable to the chemical vapour generation approach.

Here, we apply acetic acid PVG of mercury to speciation measurements with LC-AFS to provide a simpler analysis of methylmercury in three selected matrices: seafood, hair, and sediment. In total, 7 certified reference materials were analysed to assess the accuracy and precision of the method. A comparison was made between PVG and CVG methods, which showed that the PVG method provided sensitivities equal to that of the CVG method. In addition, 14 yellowfin Tuna samples were analysed using acetic acid PVG and compared with an analysis using GC-AFS, which showed good agreement of results between the two methods. In addition, the new LC-PVG-AFS method was compared to currently available ICP-MS methods to compare the sensitivity and reproducibility. Further analysis with and without vapour generation of mercury before ICP-MS detection has also been carried out.