[Method of cyanogen bromide-fluorimetry determination of trace amount of selenomethionine in grain and blood].

Selenomethionine (SeMet) reacted with cyanogen bromide (BrCN) quantitatively forms CH3SeCN. After extracted with CHCl3, the Se of CH3SeCN is acid-digested to Se(IV). Then 2,3-diaminonaphthalene is used to determine the fluorescent Se value of 4,5-benzopiaselenol. The determination limit of this method was 3 ng/g SeMet. The accuracy of 10-500 ng Se in SeMet standard was 91.8%-97.6%. RSD was 1.9%-6.3%. Recoveries for grain and blood were 92.3%-96.7%. RSD was 2.7%-5.1%. The RSD for samples was 2.7%-9.0%. Selenocystine, selenocystiene selenite and methionine did not interfere with the determination.