Journal of Pharmaceutical and Biomedical Analysis 47 (2008) 541–546 Contents lists available at ScienceDirect Journal of Pharmaceutical and Biomedical Analysis journal homepage: www.elsevier.com/locate/jpba Use of slurry suspension sample introduction technique in fast multielement analysis of multimineral and multivitamin formulations by inductively coupled plasma atomic emission spectrometry George A. Zachariadis ∗ , Agathi F. Olympiou Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece article info Article history: Received 30 November 2007 Received in revised form 25 January 2008 Accepted 12 February 2008 Available online 17 February 2008 Keywords: Metals Slurry suspensions Inductively coupled plasma emission spectrometry Multiminerals Analysis of variance abstract A slurry suspension sampling technique has been developed and optimized for rapid multielemental analysis of multivitamin/multimineral preparations using inductively coupled plasma atomic emission spectrometry (ICP-AES). The following macro-, micro- and trace-elements: Ca, Mg, Mn, Fe, Cr, Al, Ag, B, Ba, Bi, Cd, Co, Cu, Ga, In, Ni, Pb, Zn, As and Se were determined by the proposed method. The lower detection limits were obtained for Mn, Mg, Cu and Ca whereas the highest for Bi, Pb, As and Se. Consequently the method can be used as a fast screening method. A wet-acid mineralization method was applied as total recovery method for comparative purposes. Samples were prepared as slurries at a concentration of 5% (m/v) in aqueous acidic media (0.8 M HNO 3 ). Various factors affecting the sensitivity of the method were optimized. The obtained results were subjected to two-way analysis of variance to examine any significant difference between the developed slurry procedure and the wet-acid complete decomposition. Finally, the slurry suspension technique was found to be applicable in routine quality control and contamination monitoring of multimineral preparations. For the analyzed commercial preparations, the found elemental concentrations are compared to those appearing in the label of the products. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Multivitamin and multimineral supplements are designed specifically to provide a variety of essential nutrients for the body. Multivitamin supplements can help to prevent both vitamin and mineral deficiencies, and are used by many to increase essen- tial nutrients in the body and achieve additional health benefits. Multivitamins usually contain at least 100%, if not more, of the rec- ommended dietary allowance of essential vitamins and minerals [1]. Nutrients that are commonly included in a multivitamin prepa- ration are: vitamins A, B-complex, C, D, E, K, and among minerals, magnesium, zinc, calcium, iodine, selenium, copper, manganese, chromium and molybdenum, etc. Reference daily intakes for 11 significant metallic elements have been established to the follow- ing amounts: Ca (1000 mg), Cr (120 g), Cu (2 mg), Fe (18 mg), K (3500 mg), Mg (400 mg), Mn (2 mg), Mo (75 g), Na (2400 mg), Se (70 g) and Zn (15 mg) [2]. The various commercial products dif- fer at the levels of each element and furthermore some of them do not contain several of the necessary metals. Generally, two to four tablets may provide the daily amount of minor nutrients like iron and copper, but for major nutrients like calcium the amount is ∗ Corresponding author. Tel.: +30 2310997707; fax: +30 2310997719. E-mail address: zacharia@chem.auth.gr (G.A. Zachariadis). much lower. However these products do not replace the common food sources but are used only as supplements. Considering the toxicity of some elements such as chromium, lead, cadmium, etc., inspection of their content in multivitamin preparation is a necessity [3]. However, taking into account the very low content of these analytes in studied preparations, analyt- ical methods of high sensitivity should be used. On the other hand, a suitable sample preparation procedure is usually the key step in the whole method. Conventional wet-acid digestions [3–5] require about 2–3 h but are typically faster than dry ashing procedures. An alternative but less reported technique is the slurry suspen- sion nebulization, including direct aspiration of suspended sample into a suitable atomizer [6]. In this case, it is necessary to optimize the aspiration and atomization conditions to obtain reproducible results. Various element-specific detectors have been used for the analysis of multivitamin preparations including flame atomic spec- trometry or graphite furnace spectrometry [7–9]. Using flame atomic absorption spectrometry, Soriano et al. reported the acid extraction of four nutritional elements in HCl [9] with comparable results to the total digestion procedure. Despite of the fact that these techniques provide good sensitivity, they are in principle single- element detectors, thus they are not convenient for multielement analysis of samples like multiminerals. For this reason recently, inductively coupled plasma-based techniques coupled either with 0731-7085/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jpba.2008.02.010