Application of thin layer chromatography and color tests in the analysis of metronidazole

Abstract

Metronidazole belongs to the group of antiprotozoal medicines and is a potential object of research in various areas of analytical toxicology. Aim. To study the metronidazole behavior when developing with color reagents generally accepted and to determine R f values of metronidazole under chromatographing conditions in the solvent systems generally accepted in forensic toxicology. Results and discussion. It has been shown that such widely used color reagents as UV-light, iodine vapor, Wagner reagent, acidified iodoplatinate solution can be used for detecting metronidazole on chromatographic plates. Metronidazole gives positive detection results with reagents used in the TLC-screening of extracts from the biological material for substances of basic, acid and neutral nature. It has been proposed to develop metronidazole with the neutral ninhydrin solution, p -dimethylaminobenzaldehyde solution and hydrochloric acid vapors, as well as acidified iodoplatinate solution after keeping the plates in formalin vapors. The chromatographic mobility of metronidazole has been studied in 17 solvents systems; the systems are used as standard mobile phases according to recommendations of the International Association of Forensic Toxicologists for TLC-screening of organic compounds of acid, neutral and basic nature, in the general TLC-screening of organic substances in the Ukrainian forensic toxicological laboratories, and some systems investigated with the purpose of choosing the optimal individual solvents systems for the metronidazole study. Experimental part. The chromatographic plates Sorbfil® PTLC-IIH-UV and Merck® TLC SILICA GEL 60 were used as thin layers. Conclusions. The behavior of metronidazole when developing on TLC-plates with two types of a substrate (plastic and glass) and with/without luminophor (or UV-indicator) with commonly used colored reagents has been studied. The R f values of metronidazole under chromatographing conditions in the standard solvent systems used for TLC-screening of organic compounds of acid, neutral and basic nature have been determined.