DETERMINATION OF LEAD IN WHOLE-BLOOD USING INDUCTIVELY-COUPLED ARGON PLASMA-MASS SPECTROMETRY WITH ISOTOPE-DILUTION

An accurate and simple method for determination of lead in whole blood using inductively coupled argon plasma mass source mass spectrometry (ICP-MS) was developed, Determination of lead was by stable isotope dilution, using a spiking material from the National Institute of Standards and Technology (NIST), Standard Reference Material (SRM) 983, Radiogenic Lead Isotopic Standard, enriched to 92.15 at.% lead 206 (Pb-206). Two aliquots of each whole blood specimen were taken (about 0.50 g) and weighed accurately by difference, One of the aliquots was then spiked with about 100 mg of a solution prepared from SRM 983; about 1 mu g g(-1) of Pb in concentration. Both aliquots were then digested with ultrapure, concentrated nitric acid in a microwave oven. The digestate was cooled, diluted, and both unspiked and spiked digests were aspirated into the ICP-MS instrument and isotope ratios of lead 208:lead 206 were measured. The amount and concentration of lead was calculated as mu g of lead per g sample, and multiplied by 100 to give mu g of lead per 100 g of sample, This mass-basis measurement (mu g per 100 g) was then converted to mass per volume (mu g dl(-1)) using the measured density of the whole blood specimen as a correction factor. The method has been evaluated using SRM 955a to determine accuracy, The proposed method provides a standard of accuracy for determination of lead in blood in a nationally based standardization programme, the Blood Lead Laboratory Reference System (BLLRS).