Cereal Chem 49:514 - 521.  |  VIEW ARTICLE
Determination of Added Lysine in Fortified Wheat and Bulgur.

J. W. Finley, R. E. Ferrel, and D. A. Fellers. Copyright 1972 by the American Association of Cereal Chemists, Inc. 

A colorimetric procedure for determination of added lysine-hydrochloride in wheat and bulgur is described. The method is based on quantitative conversion of the alpha-amino group of free lysine to a copper complex, followed by reaction with 1-fluoro-2,4-dinitrobenzene. The solution is acidified with dilute hydrochloric acid and thrice extracted with diethyl ether; the aqueous solution is clarified by addition of ethanol and filtration. Absorbance of the resultant epsilon-dinitrophenyl lysine is measured at 390 nm.