ELECTROTHERMAL ISOTOPE-DILUTION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY METHOD FOR THE DETERMINATION OF SUB-NG ML(-1) LEVELS OF LEAD IN HUMAN PLASMA

An isotope dilution technique coupled with electrothermal volatiliztion and inductively coupled plasma mass spectrometric detection is reported for the quantitative determination of Pb in human blood plasma with a calculated limit of detection of 16 x 10(-15) g. Sample preparation is simple requiring only addition of concentrated nitric acid and a measured amount of Pb-204 spike in solution. Analysis time is typically 2.5 min, the relative standard deviation is < 2% (n=5), calculations require only simple numeric manipulations and the isotopic ratio, of the, Pb isotopes can be monitored. The Pb concentration of a commercially available dehydrated human plasma was found to be 1.27 +/- 0.02 ng ml(-1).