Determination of Elemental Compositions in Commercial Multivitamin/Mineral Dietary Supplements by using Collision/Reaction Cell ICP-MS

Commercial multivitamin and/or mineral dietary supplements contain a variable type and amount of essential and non-essential (i.e., toxic or potentially toxic) elements. Consuming too much or too little of essential elements can be detrimental to one's health, and thus the quantification of elemental content for these products must be precise [1]. The purpose of the study is to determine the elemental compositions of multivitamin/mineral dietary supplements that are available in US market.

Thirty five different dietary products (capsule, liquid or powder form) of children and adults formula were analyzed by collision/reaction cell (CRC) ICP-MS for their essential and non-essential elements including Na, Mg, Al, K, Ca, Fe, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Ag, Cd, Cs, Ba, Tl, Pb, U, Hg. Samples were digested with HNO₃+HCl (8:2) by utilizing closed vessel microwave system. The validity of the applied method was assessed by the analysis of standard reference material (SRM 3280), and the recoveries were 100±5% of the certified value for 15 elements. The linear correlative coefficients for all the elements were higher than 0.999, with RSD <3.0%. The established daily intake was compared with current recommendations listed on the label. Most of the analyzed supplements (25 out of 35 products) were found to contain Mg, K, Fe, Zn, Se and Cr at concentrations that deviated from the label claim (±10–30%). For example, sample 13 contained lower amounts as compared to the elements claimed on the label, while samples 25 and 10 contained 364mg/serving size Ca (claimed 250) and 0.02mg/serving size Ni (claimed 0.005), respectively. The established dietary intakes of toxic elements, especially As, Cd, Pb and Hg, from the 35 products tested were well within the limits.

Fig.1: Ca analysis of multivitamin/mineral dietary supplements according to the label claim using ICP-MS method

Fig.2: Heavy metal/metalloid analyses of multivitamin/mineral dietary supplements using ICP-MS method

Acknowledgements: This research is supported in part by „Science Based Authentication of Dietary Supplements“ and „Botanical Dietary Supplement Research“ funded by the Food and Drug Administration grant numbers 5U01FD002071–09 and 1U01FD003871–01, and the United States Department of Agriculture, Agricultural Research Service, Specific Cooperative Agreement No. 58–6408–2-0009. References: [1] Dwyer JT, et al. (2007) Anal Bioanal Chem 389: 37–46.