Rapid liquid chromatographic determination of fatty acids as 2-nitrophenylhydrazine derivatives

Direct derivatization of saponified fats and oils with 2-nitrophenylhydrazine hydrochloride produced corresponding fatty acid hydrazides without time-consuming sample cleanup and/or extraction steps. Hydrazides were injected directly into a liquid chromatograph. Improved isocratic separation was achieved within only 22 min for 29 saturated and mono- and polyunsaturated fatty acids (C-8:0- C-22:6), including cis-trans isomers and double-bond positional isomers. The technique has good quantitative accuracy while reducing analysis time, cost, and labor.