[Determination of 2,4-dimethylhydroxybenzene by chromatographic methods in forensic toxicological research of biological material]. / Opredelenie 2,4-dimetilgidroksibenzola khromatograficheskimi metodami pri khimiko-toksikologicheskom issledovanii biologicheskogo materiala.

OBJECTIVE: Is to develop a method for determining 2.4-dimethylhydroxybenzene (2.4-DMHOB) in biological material. The analytical methods used in the experiments were extraction, column chromatography of normal pressure, TLC, GC-MS and HPLC. To extract the analyte from the bioactive matrix, maceration with the binary insulating agent acetone-ethyl acetate (3:7) was used, observing the 2:1 mass ratio of the «insulating agent-matrix¼. Optimal conditions of semi-preparative analyte chromatography were achieved in column (150×10 mm) of «Silasbor¼ S-18 sorbent in elution with a mixture of acetonitrile-water (7:3), which was used in the proposed cleaning scheme, combining extraction and reversed-phase column chromatography. The application of the mobile phase of tetrachloromethane-dioxane (9.5:0.5) has been substantiated for the selective determination of 2.4-DMHOB by TLC («Sorbfil¼ plates). The expediency of confirming identification of the analyte in the form of 2.4-dimethyltrymethylsilylphenol using GC-MS (DB-5MS EVIDEX column (25.000×0.2 mm), stationary phase (5%-phenyl)-methylpolysiloxane, carrier gas - helium) has been shown. The group of characteristic particles in the mass spectrum of trimethylsilyl analyte derivative was represented by 45; 59; 73; 82; 91; 105; 119; 135; 149; 163; 179; 194 m/z ions. HPLC (Discovery C18 250×4.6 mm column, eluting liquid - acetate buffer solution with pH 5.5 - acetonitrile, 50:50) was used to confirm the identification and quantification of 2.4-DMHOB. A method for determining 2.4-DMHOB by the HPLC method in biological material (liver tissue) is proposed, which corresponds to the criteria of linearity, selectivity, accuracy, precision and stability. The minimum detectable quantity of 2.4-DMHOB in the bioactive matrix is 0.5 µg/g, the minimum determined quantity is 1.2 ug/g.

[Development of methods for determining and studying the persistence of 2,4-dimethylhydroxybenzene and 2,6-dimethylhydroxybenzene in biological material]. / Razrabotka metodik opredeleniya i izuchenie sokhranyaemosti 2,4-dimetilgidroksibenzola i 2,6-dimetilgidroksibenzola v biologicheskom materiale.

OBJECTIVE: 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.

[The specific features of the distribution of 2,6-di-tret-buthyl-4-methlhydroxybenzole in the organism of the warm-blooded animals].

We have studied the specific features of the distribution of 2,6-di-tret-buthyl-4-methlhydroxybenzole in the organism of the omnivorous warm-blooded animals (rats) following the intragastric administration of the three-fold lethal dose of the poisonous substance. 2,6-di-tret-buthyl-4-methlhydroxybenzole was isolated from the blood and various organs of the animals by means of acetone extraction. It was further purified on the 40/100 mcm L silicagel column with the use of hexane/acetone for elution. TLC, GC-MS, and UV-spectrophotometry were employed to identify and quantify the material of interest. It was shown that 2,6-di-tret-buthyl-4-methlhydroxybenzole undergoes modification in the internal organs and blood of the poisoned animals. In was present in the highest amounts (100 mg/g) in the stomach and small intestine contents (787.78±52.31 and 18.31±3.47 respectively), spleen (12.46±1.02), and kidneys (8.48±0.61).

[Specific features of the distribution of 2,4- and 2,6-dimethyl derivatives of hydroxybenzene in the body of the warm-blooded animals].

This study was designed to elucidate the specific features of the distribution of 2,4- and 2,6-dimethyl derivatives of hydroxybenzene in the body of the warm-blooded animals (rats) after the intragastric administration of these poisonous substances. It was shown that large amounts of these compounds are present in the unmetabolized form in the blood and internal organs of the experimental animals. Their largest quantities were found in the stomach contents, spleen, and small intestines.