Abstract
An improved quantitative method for estimating ϵ‐DNP‐lysine is described. This method is applied to the determination of ϵ‐DNP‐lysine produced by the hydrolysis of dinitrophenylated proteins. The effect of the conditions of hydrolysis and of traces of chromic acid present during hydrolysis is presented. The use of dinitrophenylation as a method of determining non‐N‐terminal lysine was tested on three purified proteins and the results are discussed.