Determination of Methadone and Its Metabolites by High Performance Liquid Chromatography Following Solid-Phase Extraction in Rat Plasma
- 1 November 1992
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Chromatographic Science
- Vol. 30 (11) , 443-447
- https://doi.org/10.1093/chromsci/30.11.443
Abstract
This paper describes a rapid, quantitative liquid chromatographic analysis and extraction of methadone and its two major metabolites from rat plasma, using difenoxin as the internal standard. Using a C18 column, resolution of all sample components and the internal standard is achieved with a mobile phase of 25:75 acetonitrile-0.08% diethylamine in 1000 mL water, pH 2.3, at a flow rate of 1.5 mL/min. The injection volume is 100 μL. Standards are linear over the range 25–100 ng, with a lower limit of detection for methadone of 0.25 ng. Within- and between-run coefficients of variation (CV) are 1.24% and 2.94%, respectively. Extraction of methadone and its metabolites from rat plasma uses a solid-phase extraction technique that is highly efficient. Extraction efficiencies of 90.3%, 99.6%, 85.9% and 93.8% were achieved for methadone, its primary and secondary metabolites, and difenoxin, respectively.Keywords
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