The isolation of Venlafaxine from the biological material by hydrophilic solvents

Abstract

The isolation of Venlafaxine from the biological material by hydrophilic solvents Aim. To determine the Venlafaxine recovery from biological tissues using generally accepted methods of drug isolation by the extraction with acidified water and acidified ethanol. Materials and methods. The studies were performed on model samples of the animal liver spiked with Venlafaxine. The drug was isolated by the extraction with water acidified with oxalic acid according to the A. O. Vasylieva method, ethanol acidified with oxalic acid by the Stas-Otto method, water acidified with sulfuric acid according to the V. P. Kramarenko method. The extracts obtained were subjected to the additional cleanup procedure by the back-extraction and TLC. Detection and the quantitative determination of Venlafaxine in the extracts obtained were performed by TLC and UV spectrophotometry. Results and discussion. While extracting Venlafaxine from the biological material with water acidified with oxalic acid, ethanol acidified with oxalic acid and water acidified with sulfuric acid, the recovery values were 44 ± 2 %, 36 ± 3 % and 28 ± 3 %, respectively. The quantitative determination of the drug in extracts was performed by the UVspectrophotometric method at λmax 277 nm according to the equation of the calibration curve y=(0.00368 ± 2×10-5)×x, which showed linearity in the range of the analyte concentrations of 25.00-300 μg/mL. Conclusions. 1. The recovery values of Venlafaxine from the biological material using generally accepted methods have been determined. The highest recovery was obtained while extracting with water acidified with oxalic acid,which was 44 ± 2 %, which provided its suitability for the sample preparation during the non-directed toxicological examination. 2. The inclusion of the additional cleanup procedure by the back-extraction and TLC into the pretreatment process made possible to apply the UV spectrophotometric method, which was linear within the range of the expected lethal concentrations of Venlafaxine in the biological material. 3. The method of the Venlafaxine isolation from the liver tissue by extracting with acidified water with oxalic acid followed by the additional optimized cleanup procedure can be recommended for the forensic toxicological examination of the biological material for the presence of Venlafaxine.