Recovery of endogenous selenium from fish tissues by open system dry ashing.

Quantitative recovery of endogenous selenium from fish tissues following dry ashing techniques has not been confirmed. An open system dry ashing procedure, using oxidative fusion with Mg(NO3)2 X 6H2O in the presence of MgO, was tested for recovery of selenium from National Bureau of Standards (NBS) Reference Materials (tuna and oyster) and selected fish tissues. Recovery after dry ashing and hydride analysis was complete from NBS Bovine Liver, Tuna, and Oyster Tissues, as well as from Food and Drug Administration cod, haddock, perch, and flounder research materials. Endogenous selenium, injected into rainbow trout (Salmo gairdneri) as 75Se, was recovered after ashing from liver, ovaries, gastrointestinal tract, muscle, bile, and carcass, 3 and 10 days post-injection. Results indicate that open vessel oxidative fusion is a rapid, simple technique applicable to quantitative recovery of selenium from organoselenium compounds that exist in various aquatic species. The diluted digestate is readily amenable to conventional hydride generation analysis.