Clinical Chemistry, Vol 20, 163-171, Copyright © 1974 by the American Association for Clinical Chemistry

Rapid Ultramicro Direct Determination of Erythrocyte Lead Concentration by Atomic Absorption Spectrophotometry, with Use of a Graphite-Tube Furnace

¹ The Department of Medicine and the Clinical Chemistry Laboratory, University of Wisconsin Hospitals, Madison, Wis. 53706.

We describe a convenient, sensitive, accurate, precise and direct method for lead analysis in blood by use of the graphite-tube furnace with an atomic absorption spectrophotometer. Advantages of this proposed method are the ultramicro sample size and the minimal sample preparation required. Interferences by the major cations and anions in blood were studied and minimized. Anticoagulants examined for matrix effects included heparin, oxalate, and ethylenediaminetetraacetic acid. Potentially serious analytical errors can result if improper sample preparation procedures are adopted in the presence of sodium, potassium, hydroxide and heparin. The surfactant "Triton X-100" did not affect lead absorption. Recovery of lead (calculated as a percentage of the lead added) from human erythrocytes diluted 1:1 with Triton X-100 ranged from 96% to 103% over several days at a wide range of concentrations. On the other hand, recovery of lead added to whole blood, serum, or plasma was always incomplete, independent of the dilution or the diluents used. Quenching effects of sodium, potassium, hydroxide, and heparin were significantly less in whole blood or diluted erythrocytes than in aqueous standards. Absorption was decreased if the standards were not kept at a pH of less than 3. Within-run, the coefficient of variation (CV) was 3.5% at an erythrocyte lead concentration of 0.480 mg/liter of packed cells. The day-to-day CV for the erythrocyte matrix was 7% and 9% at 0.324 and 0.708 mg/liter of packed cells, respectively. When erythrocytes were diluted with an equal volume of Triton X-100 solution and 4 µl of the diluted sample was injected directly into the graphite furnace, no interferences were measured. This graphite-tube furnace method for erythrocytes has high accuracy, excellent precision, extremely high sensitivity, and requires a whole blood sample of less than 10 µl. The normal range for erythrocyte lead concentration (n = 26) was 0.10 to 0.60 mg/liter of packed red cells. This proposed method of lead analysis satisfies all previous criticisms of atomic absorption measurements for lead in blood.

Submitted on July 23, 1973
Accepted on October 1, 1973