Determination of lead in whole blood by graphite furnace atomic absorption spectrometry with matrix modification

Abstract

A graphite furnace atomic absorption spectrometric (GFAAS) method for the determination of lead in whole blood specimens has been developed. Blood was diluted ten-fold with 0.01%V/V Triton X-100 solution; 10 µl of diluted blood and 10 µl of a matrix modified mixture [0.6%m/VNH₄H₂PO₄ and 0.15%m/VMg(NO₃)₂ in 0.01 M HNO₃] were automatically injected in sequence into pyrolytic graphite coated graphite tubes. For comparison purposes, atomisation from a L'vov platform was also carried out. A 0.2-nm slit width was required in order to overcome spectral interference. The characteristic masses were 23 and 15 pg of Pb per 0.0044 A s for the pyrolytic graphite coated tube and L'vov platform, respectively. In the diluted solutions, the detection limits (3σ) for the method described were 1.2 µg l^–1 of Pb (pyrolytic graphite tube) and 0.7 µg l^–1 of Pb (L'vov platform). The accuracy of the method was tested using NBS SRM 955 (a mean relative error of ca. 1% was obtained) and recovery studies were undertaken (average recoveries were 102%, range 95–105%). The precision was acceptable and an approximate standard deviation (SD) of 0.8 µg l^–1 of Pb was found for both within- and between-(day to day) run precision. The proposed method was used in studies of populations with a low risk of lead intoxication by environmental and/or occupational exposure; a mean (± SD) whole blood lead concentration of 110 ± 11 µg l^–1(n= 309 individuals) was found. The method was free from interference, reliable and reproducible.