ULTRASOUND ACCELERATED SOLID-LIQUID EXTRACTION FOR THE DETERMINATION OF SELENIUM IN BIOLOGICAL SAMPLES BY ELECTROTHERMAL ATOMIZATION ATOMIC-ABSORPTION SPECTROMETRY

A novel method for sample preparation by ultrasound-accelerated solid- liquid extraction prior to selenium determination in the phosphate-ric h biological samples by electrothermal atomization atomic absorption s pectrometry (ETAAS) with continuum-source background correction and ni ckel nitrate as a chemical modifier was established and compared with the results of conventional sample wet decomposition (however, this la st item was not the object of this study). Diluted (4%) nitric acid wa s used as an extraction medium. The evaluation of the analytical resul ts for biological Certified Reference Materials indicates that the res ults of a selenium determination after wet acid digestion (HNO3+HCl+H2 O2) agreed well with the certified values, whereas the proposed solid- liquid extraction procedure can be used for simple and rapid control o f the selenium levels.