Fluorimetric determination of selenium in some marine materials after digestion with nitric and perchloric acids and co-precipitation of selenium with lanthanum hydroxide.

A modified spectrofluorimetric method for the determination of selenium in some marine tissues is described. Selenium is isolated from potentially interfering elements by co-precipitation, then a piazselenol is formed between selenium and 2.3-diaminonaphthalene at pH 1.0 and extracted into cyclohexane. The selenium is determined fluorometrically (lambda(ex), 377 nm; lambda(em), 519 nm) in the extract. The detection limit is 3.6 rig (6 times the standard deviation of the blank) and the coefficient of variation is 4% at the 10-ng level.