Analytical Validation of a Multielement ICP-MS Method for Human Serum and Its Application to Trace Element Biomonitoring in Hemodialysis Patients

Reliable determination of trace elements in human serum is essential for clinical assessment, toxicological investigations and human biomonitoring. This study describes the development and analytical validation of a multielement inductively coupled plasma mass spectrometry (ICP–MS) method for the simultaneous determination of essential and potentially toxic trace elements in human serum (Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Ba, Bi) using a simple direct-dilution procedure with 1% (v/v) nitric acid. Method validation included assessment of linearity, limits of detection and quantification, carry-over, precision, trueness, measurement uncertainty and analyte stability. Calibration curves showed excellent linearity, with coefficients of determination (R2) ranging from 0.9993 to 1.0000 across analyte-specific calibration ranges of 0–10, 0–50, and 0–500 µg L−1. Repeatability ranged from 0.69% (Cu) to 14.5% (Ba), while intermediate precision ranged from 1.32% (Zn) to 81.1% (Cd and Bi at low concentrations). Recoveries obtained using certified serum reference materials ranged from 55% (V) to 206% (Bi) across the evaluated conditions. Meanwhile, limits of detection ranged from 0.01 (V) to 0.16 (Cu) µg L−1. Measurement uncertainty was estimated following the EURACHEM/CITAC and GUM recommendations, identifying repeatability as the principal contributor to the overall uncertainty budget. The method was successfully applied to serum samples from healthy individuals and patients undergoing chronic hemodialysis. The proposed methodology combines simple sample preparation with comprehensive metrological characterisation, providing practical approach multielement serum analysis and its application to trace-element biomonitoring investigations.