An increasing interest for natural and synthetic aldehydes and ketones has caused that a significant number of analytical papers on this subject was recently published. Until now some specific reactions of individual compounds were used in the classical organic analysis''. Addehydes were also determined using some instrumental methods, e.g. polarography2'. All these methods are non-selective and cannot be used in investigation of mixtures. Recently adsorption chromatography, partition chromatography on carrier and paper, ion-exchange chromatography and gas-liquid chromatography were used for separation of aldehydes and ketones. Attempts were made to separate these compounds as their derivatives, viz. semicarbazones, hydroxamic acid derivatives, but highly promising results were obtained using 2, 4-dinitrophenyihydrazones. This procedure has been described by many authors, who applied, among others, also reverse phase partition chromatography In this paper the chromato-polarographic method was used for the analysis of mixture of aldehydes and ketones. The chromato-polarographic method may be used for the study of species reducible at the mercury dropping electrode over the potential range, which is not too negative. Otherwise, either some indirect methods should be used", '2', or, with usually better result the polarographically inactive compounds should be transformed into reducible ones. Quantitative formation of stronly coloured, insoluble precipitates of 2, 4-dinitrophenylhydrazones of carbonyl compounds enables application of colorimetric or polaro* graphic methods to the determination of aldehydes and ketones. Nevertheless both mentioned methods are poor in selectivity and cannot be used for the analysis of mixtures of mentioned compounds.
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