Correction for spectral interference with determination of lead in blood by non-flame atomic absorption spectrometry

A non-flame atomizer incorporating a graphite tube and cup is used to determine lead in whole blood and packed erythrocytes. In a direct method, a 2-mu-l sample is treated in situ in the cup with 1 mu-l of concentrated nitric acid. The oxidized sample can then be dried, ashed, and atomized without leaving a residue. The nitric acid treatment obviates correction for nonselective absorption, something previously necessary in the determination of lead in blood by non-flame techniques. The resulting chemical conversion of the matrix compounds frees the lead atomic absorption peak from the spectral interference. Alternatively, a 50-mu-l sample of blood or erythrocytes is treated with 50 mu-l of concentrated nitric acid and a 1.5-mu-l aliquot is analyzed with use of the graphite tube.