Optimization of the Determination of Methylmercury in Solid Matrix Samples

Accurate quantification of neurotoxic methylmercury (MeHg) in environmental samples is crucial for exploring its formation, behaviors, and risks. Here, we developed and optimized an alkaline digestion-manual purge trap/gas chromatography-cold atomic fluorescence spectrometry (GC-CVAFS) method for the quantification of MeHg in solid matrix samples such as sediments, soils or sedimentary rocks. The alkaline digestion method yielded higher recoveries of MeHg than the acid extraction method. The manual purge trap/GC analysis enhanced the detection of MeHg by increasing the loading volume of the digestion solution, thereby facilitating the detection of lower concentrations of MeHg in the samples when compared to fully automated analysis. The optimized method achieved a method the limit of detection (LOD) of 0.0263 ng·g^-1 and a limit of quantification (LOQ) of 0.0876 ng·g^-1 with relative standard deviations of less than 10%. These results suggest that the alkaline digestion method is appropriate for the pretreatment and quantification of MeHg analysis in sediments or soils, particularly those from non-Hg contaminated sites.