Simultaneous determination of manganese and selenium in serum by electrothermal atomic absorption spectrometry

A method for determination of manganese and selenium in serum by simultaneous atomic absorption spectrometry (SIMAAS) is proposed. The samples (30 μl) were diluted (1+3) to 1.0% v/v HNO3+0.10% w/v Triton X-100 directly in the autosampler cups. A total of 20 μg Pd+10 μg Mg(NO3)2 was used as chemical modifier. The pyrolysis and atomization temperatures for the simultaneous heating program were 1200 and 2300 °C, respectively. The addition of an oxidant mixture (15% w/w H2O2+1.0% v/v HNO3) and the inclusion of a low temperature pyrolysis step (400 °C) attenuated the build-up of carbonaceous residues onto the integrated platform. An aliquot of 15 μl of the reference or sample solution was introduced into the graphite tube and heated at 80 °C; subsequently, 10 μl of oxidant mixture+10 μl of chemical modifier was introduced over that aliquot and the remaining heating program steps were executed. This strategy allowed at least 250 heating cycles for each THGA tube without analytical signal deterioration. The characteristic masses for manganese (6 pg) and selenium (46 pg) were estimated from the analytical curves. The detection limits were 6.5 pg (n=20, 3δ) for manganese and 50 pg (n=20, 3δ) for selenium. The reliability of the entire procedure was checked with the analysis of serum from Seronorm™ Trace Elements in Serum (Sero AS) and by addition and recovery tests (97±9% for manganese and 96±7% for selenium) using five serum samples.