Optimized mercury speciation analysis using LC-ICP-MS and microwave assisted extraction for precise determination of methylmercury in fish, rice and soil

Abstract

Mercury (Hg) is a toxic element that exists in various forms, each with its characteristics and impacts on the environment. Methylmercury (MeHg) bioaccumulates in the food chain and identifying mercury species is crucial to assessing risks to ecology and health. Therefore, accurate, sensitive, and broad-range analytical methods are essential for the determination of methylmercury. This study optimized and validated a procedure for Hg speciation analysis in rice, fish, and soil using different extractants, followed by liquid chromatography inductively-coupled plasma mass spectrometry (LC ICP-MS) using certified references. Microwave-assisted extraction (MAE) parameters were optimized using 25 % KOH, resulting in improved sensitivity, accuracy and processing time. The validated method achieved a limit of quantitation (LOQ) of 12 µg kg−1 and showed acceptable percentage recoveries (75.3–98.1 %) in all matrices, enabling precise determination of MeHg (%RSDr; 3.76–5.78, %RSDR; 2.34–6.75) and Hg in a large number of samples within a short time frame. The validated method is particularly well-suited for rice, followed by fish and then soil. Therefore, the method utilizing microwave-assisted extraction and LC ICP-MS ensures precise methylmercury determination in rice, fish, and soil, crucial for evaluating environmental and health risks associated with mercury bioaccumulation.