SPECIATION OF SELENOAMINO ACIDS BY ONLINE HPLC ETAA SPECTROMETRY

An analytical method was developed to determine selenoamino acids in t he presence of other compounds. Separation has been achieved by High P erformance Liquid Chromatography (HPLC) using electrothermal atomic ab sorption (ETAA) spectrometry as a very sensitive and element-specific detector. On-line HPLC ETAAS speciation of selenocystine and selenomet hionine has been studied, using a laboratory made interface. Analytica l characterization of the method has been realized with standard solut ions. Using a 100 mul sample loop, the detection limits were calculate d as 8 mug l-1 for selenomethionine and 10 mug l-1 for selenocystine w ith repeatability and reproducibility of 4% and 7% respectively. The m ethod has been applied to the determination of selenoamino acids in an extract of white clover (CRM402) certified for total selenium.