Improved determination of selenium in serum by Zeeman atomic absorption spectrometry.

We have improved Zeeman atomic absorption spectrometric determination of selenium in serum by using an acidic solution of Ag + Cu + Mg as a matrix modifier and performing the charring step in flowing O2. Under these conditions, we could calibrate serum results with selenium standards in bovine albumin solutions. Mean analytical recovery was 98%, and the CV was 1.8% within runs, 2.9% between runs. Analysis of Reference Materials from the U.S. National Bureau of Standards (SRM 909 and RM 8419) yielded the values of 106 (SD 2.4) and 15 (SD 1.6) microgram/L, respectively, in good agreement with the expected values (106 and 16, respectively). The method--being reliable and relatively simple and rapid--is suitable for use in epidemiological screenings. Mean selenium concentrations in serum sampled from 274 adults in central Italy were 90 (SD 15) microgram/L. For 11-year-old children, these values were lower and showed a tendency to sex-related difference: 82 (SD 9.9) microgram/L for 97 boys, 78 (SD 9.3) microgram/L for 90 girls.