A dinitrophenylation method for the micro-determination of amide nitrogen

A new micro-method is reported for the determination of amide nitrogen, based on the estimation of 2,4-dinitroaniline produced by the reaction between ammonia, quantitatively liberated from the protein, and 1-fluoro-2,4-dinitrobenzene. Application of the method to 0.5-mg samples of wool gives results in agreement with those obtained by other authors for the same type of wool. Analyses of cuticle-rich material obtained from these wool samples show that in one sample out of three the cuticle is significantly poorer in amide groups than the whole fibre The mean standard error taken over all the analyses is 4 5 %.