[Increasing the threshold sensitivity of the spot detection reaction on a chromatogram].

A known analytical procedure was used for increasing the sensitivity threshold of the reaction of the zone opening on chromatogrammes. The procedure was the following: the carboxylic acid admixtures determined chromatographically were previously extracted from dry samples of the test-compounds into an optimal solvent. The expediency of the procedure was shown on examples of phenylacetic, phenoxyacetic and isoxasolcarboxylic acids present as admixtures in semisynthetic penicillins and raw materials used for their preparation. The threshold sensitivity was increased by 6 to 9 times. The chromatographic separation was performed in a fixed layer of Silica Gel KSK treated with a buffer. The mobile phase was used in the form of a solvent system: n-heptan-glacial acetic acid (95:5).