[Fluorometric determination of selenium in breast milk: studies on wet ashing]

A fluorometric method for the determination of selenium content in breast milk was studied. After the wet ashing of breast milk with nitric acid and perchloric acid at 160 degrees C for about 2.5-3 hours and the reduction with 6 mol/l hydrochloric acid, selenium was determined by 2,3-diamino-naphthalene fluorescence reaction. The method described here is very simple and all procedures were performed in a single-test-tube, and fifty samples could be assayed within 5 hours. With this method, analytical recoveries of 20 ng/ml and 50 ng/ml selenium added to breast milk were 95.3% (n = 10, cv = 5.96%) and 100.8% (n = 10, cv = 5.72%). Selenium contents of breast milk obtained from 37 Japanese women delivered healthy were 22.0-71.6 ng/ml, mean = 40.79 ng/ml (1 week postpartum) and 12.0-40.8 ng/ml, mean = 24.52 ng/ml (1 month postpartum).