HG-FAAS DETERMINATION OF TRACE AMOUNTS OF LEAD IN VEGETABLES

Atomic absorption spectrometry,hyphenated with hydride generation technique,was applied to the determination of traces of lead in vegetables.The sample,after washing and grinding,was digested with HNO3 and H2O2 by heating in a microwave oven.The effects of varieties of acid and acidity of the sample solution and the amount of potassium borohydride used in the hydride generation reaction on the magnitude of the absorbancy of atomic absorption were studied.The interferences of co-existing ions in the sample were eliminated effectively by the addition of solutions of K3Fe(CN)6 and oxalic acid.Linear relationship between the absorbance and concentration of Pb2+ ion in the range of 0 to 40 μg·L-1 was obtained.The precision test with 20 μg·L-1 of Pb2+ for 7 determinations gave a value of RSD of 1.5%.The detection limit (3S) of the method was found to be 0.023 μg·L-1.In application of the method to the analysis of several kinds of vegetable samples,recoveries in the range of 978% to 105.6% were obtained.