Elemental impurities in Yataprasen Thai Polyherbal Formulation: source-dependent variation, and analytical method validation.

The global consumption of complementary and alternative medicine (CAM) has risen dramatically. However, safety concerns persist owing to contamination with elemental impurities. In this study, we optimized and validated an analytical method for quantifying four toxic metals, As, Cd, Pb, and Hg, in Yataprasen (YTPS) extract, a complex Thai traditional polyherbal formulation. Samples were obtained from natural collection sites and commercial sources, and the contributions of 13 individual herbs to total impurities were evaluated. Inductively coupled plasma mass spectrometry (ICP-MS) was applied following four acid-digestion protocols. Quantification involved external calibration and standard addition, with validation covering LOD, LOQ, linearity, precision, and recovery. Toxicological risk was assessed in accordance with the ICH Q3D(R2) guideline. Digestion with 1 mL of HNO3 gave the highest accuracy and recovery. Cd and Pb levels showed little variation across methods. Validation demonstrated excellent accuracy (93.6-107.5% recovery), strong linearity (R2 > 0.998), and low detection limits (<1.5 µg/kg). A significant difference in elemental impurity concentration was observed between the two sources, with the naturally collected YTPS exhibiting markedly higher levels of all four metals than the commercial one. While external calibration was sufficient for commercial samples, standard addition was required for naturally sourced samples to overcome matrix effects. Component analysis identified Allium sativum L., Cymbopogon nardus (L.) Rendle, and Melia azedarach L. as the major contributors to the impurity burden. Source-dependent variation in elemental impurity concentration was observed in YTPS extracts, with natural collection posing a greater toxicological concern. The validated analytical workflow provides a robust platform for quality control and regulatory assessment of traditional polyherbal formulations.