[Development of methods for determining and studying the persistence of 2,4-dimethylhydroxybenzene and 2,6-dimethylhydroxybenzene in biological material].

To study the features of the determination and preservation of 2.4-dimethylhydroxybenzene and 2.6-dimethylhydroxybenzene in biological material. Extraction, semi-preparative chromatography, TLC, GC-MS and UV spectrophotometry are considered as methods of analysis. The 2.4- and 2.6-dimethylhydroxybenzenes were isolated from the biomaterial by double infusion (30 minutes each) with a mixture of ethyl acetate-acetone (7: 3) at a weight ratio of the insulating liquid and biomaterial of 2:1. Purification was carried out by extraction and chromatography in a semi-preparative (190×10 mm) column of silica gel L 40/100 µm using the eluent hexane-dioxane-propanol-2 (80: 5: 1). Analytes were determined by TLC (Sorbfil plates, mobile phase hexane-dioxane-propanol-2 (120: 5: 1)), GC-MS (DB-5MS EVIDEX column (25 m × 0.2 mm) with a stationary phase (5%-phenyl) - methylpolysiloxane), UV spectrophotometry (solvent - 95% ethanol). The developed methods for the determination of 2.4- and 2.6-dimethyl derivatives of hydroxybenzene in biomaterial (liver tissue) are validated according to the criteria of linearity, selectivity, correctness and precision. The study of the dynamics of decomposition of 2.4- and 2.6-dimethyl hydroxybenzene derivatives in model mixtures with liver tissue, carried out using the developed techniques showed that with an increase in temperature the duration of preservation of analytes in biological material decreases. Moreover, the 2.4-isomer is more stable during storage than the 2.6-isomer. At temperatures of -25 °C, 0-2 °C, 8-10 °C, 20-22 °C, 36 °C the duration of retention of 2.4-dimethylhydroxybenzene is 402, 379, 358 and 224 days, respectively, the duration of retention of 2.6-dimethylhydroxybenzene is 356, 312, 224 and 136 days, respectively.