GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRIC DETERMINATION OF LEAD AND CADMIUM IN FOODS AFTER SOLVENT-EXTRACTION AND STRIPPING

The APDC-MIBK extraction system was modified to enable determination of lead and cadmium in foods with detection limits of 20 and 1 ng, respectively. Metals were extracted from HNO3-HCIO4 digests at pH 1.4-1.8 into MIBK (70 mL), stripped into HNO3 (3%) and H2O2 (8%), and the stripping solution was modified with a solution of ammonia and ammonium dihydrogen phosphate to optimize determinative precision and accuracy. Advantages were: (1) few interferences and sample-size limitations (up to 13 g dried kidney was analyzed), (2) consistent determinative precision (usually about 1% s/&&using graphite-furnace atomization, (3) good accuracy for five NBS standard reference materials, (4) standards did not require extraction, and (5) “acid-soluble” and “acid-insoluble” lead could be sequentially determined. © 1979, American Chemical Society. All rights reserved.