Analysis of Bismuth and Lead in Milk Powder Solvent Extrsction -Flameless Atomic Absorption Spectrometry

Abstract

The determination of bismuth and lead in foods was examined using a flameless atomic absorption spectrometer equipped with a carbon tube. To elminate the matrix effect, which is observed in direct measurements of acid test solutions, the organic layer obtained by extraction of a test solution (pH ca. 8) with a sodium diethyldithiocarbamic acid (DDTC) -methylisobutylketone system was injected into a carbon tube. Examination of ashing and atomizing conditions gave optimum sensitivities of 3 (bismuth) and 5ppb (lead) for 1% absorption. Coefficients of variation obtained by repeated extractions and injections were 1.9 (bismuth) and 3.4% (lead). Linear standard curves were obtained up to 120 (bismuth) and 100ppb (lead). Although the coexistence of chelating metal ions with DDTC caused some interference it is possible to detemine these metals with fairly good accuracy by a calibration method without using standard addition procedures when this method is used for the analysis of bismuth and lead in modified milk powder.