Determination of Poisonous Metals by Atomic Absorption Spectrophotometry. III. : Determination of Microamount of Lead with the Use of Long Absorption Tube

Abstract

A rapid and convenient method for the determination of microamount of lead in foods and pharmaceuticals by atomic absorption spectrophotometry was described. The absorption tube 50 cm in length was used to improve the analytical sensitibity for lead. The samples were decomposed by the oxygen bomb method, and the combustion products were dissolved in 0.1 N nitric acid. pH of the solution was adjusted to 9-10, and the lead chelated with APDC (ammonium pyrrolidine dithiocarbamate) was extracted into chloroform. The chloroform solution was sprayed into the absorption tube by a mixture of air and hydrogen, and the absorption of lead was measured at 2833 A. Experimental conditions such as analytical lines, extraction of APDC-Pb complex into chloroform and the influence of coexsisting elements, were examined and the optimal conditions for the determination of lead were established. The linearity of calibration curve for lead was maintained in the range from 0.05 to 1.2 μg/ml. In the recovery test, mean value of recovery of lead added to glucose at levels between 5 and 15 μg was 93.0%. The analytical results obtained by present method for lead contained in polished rice, green tea and P. V. P. (polyvinylpyrrolidone) agreed well with those found by other methods including polarography.