SELECTION OF SAMPLE PREPARATION CONDITIONS FOR CLOZAPINE FROM BIOLOGICAL FLUIDS BY LIQUID-LIQUID EXTRACTION
DOI:
https://doi.org/10.11603/2312-0967.2026.3.16332Keywords:
Clozapine, biological fluids, blood, urine, UV spectrophotometry, isolationAbstract
The aim of the work. This study aimed to develop methods for isolating and determining clozapine using liquid-liquid extraction, with a particular focus on chemical toxicological analysis (CTA).
Materials and methods. This paper presents methods for extracting clozapine from model mixtures of urine and blood plasma using liquid-liquid extraction. The study used biological fluid samples spiked with clozapine. The analyte was isolated from the blood and urine samples using liquid–liquid extraction with chloroform in an alkaline medium (pH 10). To remove endogenous impurities, a preliminary extraction step was performed using a 95:5 mixture of hexane and isopropyl alcohol under acidic conditions (pH 1). During preparation of the blood sample, cellular components were precipitated using a 1% solution of trichloroacetic acid. Clozapine was quantitatively determined by UV spectrophotometry following additional purification by thin-layer chromatography.
Results and discussion. Identification of clozapine in the obtained extracts was carried out using UV spectra, which matched those of a standard solution of the drug in ethyl acetate. The absorption maximum was observed at 261 ± 2 nm. Quantitative analysis was based on a linear calibration curve (y = 0.0047x + 0.0348) in the concentration range of 50.0–200.0 μg/mL, with a correlation coefficient (R²) of 0.9985. The average recovery of clozapine was found to be 33.02% for blood and 71.48% for urine.
Conclusions. The proposed approach for isolating clozapine from biological fluids using liquid-liquid extraction has been developed. UV spectrophotometry has been successfully demonstrated as a method for identifying and quantifying this compound, as confirmed by the obtained validation characteristics. These results can be used in forensic toxicology, particularly when investigating cases of poisoning involving psychotropic substances.
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