Optimization and validation of a simple extraction method coupled with ICP-MS for the determination of essential and toxic elements in liquid dietary supplement products

This study aimed to develop and validate a fast, easy, cost-effective, and accurate method for determining Mn, Co, Ni, Cr, Cu, Fe, Zn, As, Cd, Hg, Sb, and Pb in liquid dietary supplements using an inductively coupled plasma mass spectrometer (ICP-MS). Two sample preparation methods were compared: microwave acid digestion and direct analysis after dilution. Both methods provided acceptable recovery values (87.7 -111 %), with RSD values up to 6.35 %. The microwave digestion method was validated using various certified reference materials (CRMs) and a proficiency test (PT). Additionally, 34 domestic dietary supplements were analyzed using both methods, and the results were similar. Only one sample exceeded the maximum allowable limit for arsenic, which is 150 mg/kg set by the United States Pharmacopeia (USP). Two products had high Fe and Zn levels exceeding the recommended daily allowance (RDA), according to the Food and Drug Administration (FDA). This study demonstrates the effectiveness and advantages of the direct analysis method for measuring essential and toxic elements in liquid dietary supplements. This method promotes green chemistry principles and provides valuable information for ensuring consumer safety and product quality.