On the optimization of blood lead standards in electrothermal atomization atomic absorption spectrometry

This study is concerned with the optimization of blood lead standards in EDTA-AAS (electrothermal atomisation-atomic absorption spectrometry), using a direct method, i.e. the determination of lead in 15-fold diluted blood. With three bottles of whole blood containing respectively heparin, citrate and EDTA as an anticoagulant, and 14 working standard solutions, 42 calibration curves were constructed. It appeared that standards prepared in heparinised blood yield calibration curves with a less steep slope than in the case of citrate of EDTA blood. As a primary standard, lead acetate is considered best for both heparinised and citrated blood; metallic lead is advantageous for EDTA blood. In all cases a low pH of both stock standard and working standard solution is preferred. Using a reference sample the best conditions for obtaining accurate results were investigated. The use of metallic lead as a primary standard ensures a combination of low systemic error with high precision and steep slope.