The detection of keto acids in biological fluids by two dimensional paper chromatography of their 2,4-dinitrophenylhydrazones

After conversion to 2,4-dinitrophenylhydrazones, keto acids in biological fluids were extracted into isopropyl ether followed by NaHCO 3 and finally into ethyl acetate. The derivatives were chromatographed two-dimensionally on Whatman No. SG 81 paper. Limitations of the extraction and chromatographic procedures are discussed but it is considered that the method is superior to orthodox one-dimensional paper chromatography.