METHODS OF ANALYSIS USED FOR THE DETERMINATION OF SELENIUM IN MILK AND INFANT FORMULAS - A REVIEW

Selenium (Se) occurs naturally in a range of oxidation states as volat ile species or analogues of organic sulphur compounds. Over a narrow c oncentration range (< 1 mg/day), selenium is an essential element for growth of animals and man. However at higher concentrations (> 3 mg/da y) it possesses toxicological properties. Low levels of the element in most foods including milk and infant formulae require a sampling proc edure to be followed and the use of certified reference material. Accu rate quantitative analysis is dependent on the initial digestion stage of the food matrix and the reduction of Se(VI) to Se(IV) in the final determination. In view of the difficulty in obtaining some reagents ( e.g. 2,3-diaminonapthalene), alternative procedures to the classical f luorometric technique need to be evaluated. Methods for the determinat ion of Se are described detailing detection limits, sensitivity, inter ferences and matrix-related problems.