Improved determination of microgram amounts of lead in food with a radioactive tracer

Abstract

Microgram amounts of lead in food are determined by use of a radioactive tracer. The radioactive tracer, lead-212, is radiochemically purified from thorium nitrate and is used for chemical yield determination. Food sample dissolution involves freeze drying and wet ashing to minimise contamination and eliminate volatilisation. The stable lead is determined spectrophotometrically as the dithizone complex at 510 mµ. The chemical recovery for analysis is 94 per cent., and the precision of analysis is better than 10 per cent.