Rapid Determination of Toxic Trace Metals As, Hg, Tl, and Pb in Hair by Monochromatic Excitation X-ray Fluorescence Spectrometry

Monochromatic excitation X-ray fluorescence (ME-XRF) spectrometry emerges as a novel technique in trace element analysis, distinguished by its simplicity, rapidity, and efficiency. Its application in forensic toxicology has grown significantly for identifying toxic trace metals in biological samples. This study further expands its utility by developing a method for the rapid determination of arsenic (As), mercury (Hg), thallium (Tl), and lead (Pb) in hair samples. Calibration curves were established using analytical reference samples, and optimal detection conditions were determined and validated. The LODs for As, Hg, Tl, and Pb were 0.03, 0.03, 0.03, and 0.05 μg g⁻¹, respectively. Method precision was evaluated through seven parallel analyses of samples within the concentration range of 0.27 to 20.051 μg g⁻¹, with relative standard deviations (RSDs) consistently below 10%. The feasibility of the ME-XRF technique for forensic toxicology analysis was validated through the analysis of authentic poisoned hair samples collected from the animal experiment.