high-performance liquid chromatography of short-and long-chain fatty acids as 2-nitrophenylhydrazides

Both short- and long-chain fatty acids including mono- and polyunsaturated fatty acids, were coupled with 2-nitrophenylhydrazine hydrochloride in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and analysed by high-performance liquid chromatography. Elutions of mixtures of both short- (C2C8) and long-chain (C10C18 fatty acid hydrazides were achieved within 15 min. By use of a visible-range detector (400 nm) the detection limits of both short- and long-chain fatty acids were found to be in the range 10–15 pmol per injection, and linear relationships were obtained over the concentration range 20 pmol—1 nmol per injection. Ultraviolet detection (230 nm) for the long-chain fatty acids demonstrated that the detection limits were 2.5–5 pmol per injection with linearity over the range 5 pmol—1 nmol per injection.