Total determination of essential and toxic elements in milk whey by doublefocusing ICP-MS

A method is presented for the multielemental analysis of a wide range of el ements in milk whey, using a double focusing ICP-MS instrument. Whey sample s were diluted, 1+4 for minor and trace elements and 1+1999 for major eleme nts, with ultrapure water and addition of Ga, Y, Rh, In and Tl as internal standards. Two different scans were used for the analysis. The first scan, m/Delta m = 300, for the analysis of Sr, Cd, Hg and Pb and the second scan, m/Delta m = 3000, for the analysis of Na, Al, Ca, Mg, Cr, Mn, Fe, Ni, Cu, Zn and Se. The lower background and greater;sensitivity of double focusing instruments at low resolution mode provide better detection limits than qua drupole based instruments. A reference material, BCR Natural skim milk powd er (CRM 063R), was analysed for the validation of the proposed method. The found levels show a good concordance with certified levels. The method was also applied to the multielemental analysis of human milk whey, cow milk wh ey and formula milk whey. The results obtained show considerable difference s in trace element content on human, cow and formula milk whey.