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

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.