Study of Selenium Speciation in Selenized Rice Using High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometer

On the basis of Osborne fractionation, albumin, globulin, protamine and glutelin in selenium (Se)-rich rice were extracted with water, 2% NaCl solution, 70% alcohol and 0.5% alkaline solution subsequently. The content of Se in these protein extracts was determined by inductively coupled plasma mass spectrometer (ICP-MS). The chemical forms of Se in albumin extract and enzymatic digests of rice were analyzed with a hyphenated technique of high-performance liquid chromatography and ICP-MS. The Se content in four types of extracts shows an order of glutelin > protamine > albumin > globulin. The protein with molecular weight of 12.6 kDa is the primary Se-containing protein in extracts of albumin, and selenocysteine is the predominant selenoamino acid in the enzymatic digests of rice.