Flameless atomic absorption spectrophotometry of selenium in whole blood

In this method of analysis for selenium in whole blood by flameless atomic absorption spectrophotometry, 1 mL of sample is first digested with perchloric and nitric acids. After reduction and neutralization, the sample is reacted with 2,3-diaminonaphthalene, and the product is extracted into toluene. Twenty microliters of the extract is injected into the graphite furnace of a flameless atomic absorption spectrophotometer, along with 20 microliters of a 1.0 g/L cupric nitrate solution. Blood-based standards are used to establish the standard curve. The amount of selenium required to give an absorbance of 0.0044 is 5.3 micrograms/L. Precision is good, recovery excellent. The extract is stable for 24 h.