Development and Validation of an ICP-MS/MS Method for Multi-elemental Analysis of Human Hair with Application to...

Human hair has emerged as a promising non-invasive matrix for assessing long-term exposure to essential and toxic trace elements relevant to cardiovascular disease. However, its clinical applicability depends on the availability of robust and fully validated analytical methodologies capable of overcoming matrix-related challenges. This study aimed to develop and validate a reliable and high-throughput method for multi-elemental (As, Cd, Cu, Pb, Se and Zn) analysis of human hair using microwave-assisted acid digestion followed by ICP-MS/MS, and to explore its potential application in a pilot cohort of heart failure (HF) patients. Method validation was performed using the certified reference material ERM-DB001. Analytical performance was evaluated in both no-gas and He-KED modes, assessing precision, trueness, procedural detection limits, and measurement uncertainty according to EURACHEM/CITAC guidelines. The influence of sample mass (20-200 mg) was also investigated. The validated method was subsequently applied to hair samples from 25 HF patients and 25 control subjects. The method demonstrated satisfactory intra- and inter-day precision, particularly for Cd, Cu, Se, and Zn. He-KED mode effectively reduced polyatomic interferences, improving selectivity and lowering detection limits for elements such as As and Se. Optimal analytical performance was achieved for sample masses between 60 and 100 mg, while lower masses resulted in increased uncertainty. In the pilot application, exploratory differences were observed for Pb, Mg, Ca and Zn concentrations, together with changes in selected elemental correlations (Mg/Na, Pb/Mn, Sr/Ni, Fe/Al, Fe/Ti and Mn/Ti) between heart failure patients and controls. The validated ICP-MS/MS method provides a sensitive and reliable approach for multi-elemental analysis of human hair. Its robustness and applicability to real samples support its potential use in clinical and epidemiological studies, although further research with larger cohorts is required to confirm the observed trends.