Dynamic Reaction Cell-ICP-MS as a Powerful Tool for Quality Control of a Se-Enriched Dietary Supplement
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Dynamic Reaction Cell-ICP-MS as a Powerful Tool for Quality Control of a Se-Enriched Dietary Supplement Jefferson Rodrigues de Souza 1,2 & Lilian da Silva 1 & Márcia Silva da Rocha 1 & Tatiana Dillenburg Saint’Pierre 2
Received: 20 September 2016 / Accepted: 6 March 2017 # Springer Science+Business Media New York 2017
Abstract The aim of this work was to evaluate different approaches employing a reaction cell to circumvent spectral interferences over 80Se+ to increase the sensitivity in the determination of Se by inductively coupled plasma mass spectrometry (ICP-MS). Different gases (NH3, CH4, and O2) were employed, and the operating conditions were optimized by a central composite design, evaluating the effect of the reaction gas flow rate and the rejection parameter q (Rpq) on the limit of detection (LOD) of the method. All reaction gases studied reduced the interference by 40Ar2+ over 80Se+, reducing the LOD when compared to the LOD obtained with ICP-MS operating in the standard mode (LOD = 0.2 μg kg−1). A better LOD (0.01 μg kg −1 ) was obtained with CH 4 , while 0.1 μg kg−1 was the LOD with NH3. The use of O2 as a reaction gas enabled the determination of Se at m/z 96 ( 8 0 Se 1 6 O + ) with adequate analytical performance (LOD = 0.03 μg kg−1). The accuracy of the method was evaluated by analyzing the certified reference material (CRM) Selm-1, and the results obtained ranged from 99 to 104% of the certified value. In addition, Se dietary supplements of four different brands and commercial yeast were analyzed, and the major sources of uncertainty were studied. The dietary supplements followed the criteria adopted by Brazilian legislation, although the uncertainty study highlighted the great
* Jefferson Rodrigues de Souza [email protected]
1
National Institute of Metrology, Quality, and Technology (INMETRO), Duque de Caxias, RJ, Brazil
2
Department of Chemistry, Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Rio de Janeiro, RJ, Brazil
variation in the Se content of each brand. Clearly, the manufacturing process of dietary supplements needs more rigorous quality control, considering that this product can affect the health of consumers. Keywords Selenium . ICP-MS . Reaction cell . Dietary supplement . Yeast sample
Introduction Selenium is an essential element in the antioxidant function of some enzymes. Selenium-deficient diets are known to be responsible for some health disorders such as Keshan disease (a cardiomyopathy that affects women of childbearing age) and Kaschin-Beck disease (an articular disease that results in bone damage) (Chen et al. 1980; Ge and Yang 1993). To minimize the impact of a Se-deficient diet, Se-enriched dietary supplements are commonly used. In this case, it is important to know the Se chemical form, since the organic Se is more bioavailable than inorganic Se in biochemical processes. Commercial Se supplements are widely used and generally are obtained from Saccharomyces cerevisiae enriched in organic Se, which has selenomethionine as the main s
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