DETERMINATION OF SELENIUM IN ORGANIC-COMPOUNDS ON A SILICA-GEL SINTERED THIN-LAYER CHROMATOGRAPHIC PLATE WITH 2,3-DIAMINONAPHTHALENE AFTER DIRECT DIGESTION

Biologically interesting selenium compounds such as selenomethionine, selenocystine and trimethylselenonium were digested directly on a silica gel sintered thin-layer chromatographic (TLC) plate. Digestion was performed with nitric acid-perchloric acid (2:1, v/v) by heating at 210-degrees-C for 15 min. Selenite formed on the plate was revealed with 2,3-diaminonaphthalene reagent and determined using a TLC scanner. The recoveries of selenomethionine, selenocystine and trimethylselenonium were 94 +/- 7, 99 +/- 9 and 97 +/- 10%, respectively, with a detection limit of 0.4 ng of selenium. Linearity between fluorescence intensity and selenium content was found in the range 3-250 ng of selenium.