A Convenient Method for Gas-chromatography of 2, 4-Dinitrophenyl-hydrazones of Carbonyl Compounds and Oxo-Fatty Acids

The carbonyl compounds are trace constituents which generally relate to the food flavor and roast flavor. The direct gas chromatography of the 2, 4-DNPH derivatives of carbonyl compounds was investigated. Linear relationship between the logarithmic reten-tion time and the carbon number was found and the structures of unidentified components were inferred from this relation. The separation of the 2, 4-dinitrophenylhydrazones of oxo-fatty acids methylated with diazomethane was attained by gas chromatography. This method appears to be a good supplementary means for the identification of oxo-fatty acids. The 2, 4-DNPH's purified by sublimation under reduced pressure were separated by gas chromatography without decomposition. During the process of gas chromatography, the syn-and anti-forms of 2, 4-DNPH's appeared to isomerize into the thermal equilibrium state.