Development of conditions for Pyrazidol identification in the urine in the presence of its biotransformation products by thin layer chromatography and mass spectrometry

For the analytical diagnosis of drug poisoning, it is important to develop conditions for the detection of both native compounds and products of their biotransformation in biological samples. Aim. To develop a method for isolating the antidepressant drug Pyrazidol from the human urine in the presence of its biotransformation products and determine the conditions that are suitable for analytical diagnostics of thymoleptic intoxication for their detection by thin layer chromatography. Materials and methods. The study was conducted with the human urine samples collected after taking a single therapeutic dose of Pyrazidol. The urine was subjected to the acid hydrolysis, and the antidepressant and its metabolites were extracted from the hydrolysate with chloroform from an alkaline medium at pH 8-9. Concomitant endogenous admixtures were removed by extraction with diethyl ether from an acidic medium at pH 1. For the chromatographic study of the extracts, four mobile phases recommended by the International Association of Forensic Toxicologists for TLC screening of drugs, and Merck chromatographic plates were used. Color reactions were performed on pieces of chromatographic plates with a number of chromogenic reagents most commonly used in chemico-toxicological analysis. Metabolites were identified by electron impact mass spectrometry. Results and discussion. The native substance and dehydropyrazidol were detected in the urine hydrolysates by TLC, their chromatographic mobility parameters in four TLC screening systems, as well as the results of their color reactions with the chromogenic reagents were determined. Conclusions. Conditions for isolating Pyrazidol and its biotransformation product from the urine have been proposed. The method for detecting the native compound and dehydropyrazidol in the urine extracts by TLC and mass spectrometry after taking a single therapeutic dose of the drug has been developed. The method is recommended for use in the practice of forensic and clinical toxicology.