ASVA Determination of Lead in Blood with Stepwise Pre-enrichment Through Tandem Electrolytic Cells

Two thin layer electrolytic cells, with a large area Hg-film GCE (278.5 mm2) in the former cell and a small area Hg-film GCE (3.14 mm2) in the later cell, were linked in tandem and used for enrichment of Pb2+ from blood sample, which was obtained by diluting the blood for 10 times. Lead(Ⅱ) in the sample was enriched on the large area electrode in the 1st cell and thence stripped from the electrode, and enriched again on the small area electrode in the 2nd cell, and then the anodic stripping voltammogram was recorded by potential scanning at a rate of 300 mV·s-1. Cadmium(Ⅱ) was used as internal standard. Linear relationship between values of 1st derivative of peak height and mass concentration of Pb2+ was obtained in the range within 140 μg·L-1, and the detection limit (3s/k) found was 0.41 μg·L-1 (time of enrichment: 20 s). A blood sample was analyzed by this method, and recovery was tested by standard addition method at 6 concentration levels, giving values of recovery in the range of 108.6%-111.6%.