Anodic stripping voltammetry procedure modified for improved accuracy of blood lead analysis

Abstract

In evaluating the accuracy and reliability of blood lead (PbB) measurements with the Environmental Science Associates Model 3010A Trace Metal Analyzer, intralaboratory comparison demonstrated that use of the operating conditions recommended by the manufacturer resulted in consistently underestimated PbB concentrations < 400 μg/L and overestimated PbB values > 400 μg/L. At PbB concentrations <50 μg/L, measured concentrations were often registered as negative results. However, these negative results could be replicated to within ± 10 μg/L, indicating good precision of the method, but obviously not good accuracy. In addition, lower-than-expected lead (Pb) values were measured in samples containing increased concentrations of copper (Cu), such as may occur in pregnant women. We modified the procedure to eliminate these inaccuracies by substituting manual peakheight measurements for reliance on the integrator and digital display of the instrument. We established the accuracy of the modified procedure by using calibration standards previously quantified by isotope dilution-mass spectroscopy. A quality-control program for monitoring PbB analysis is also described.