Simultaneous determination of quinine and four metabolites in plasma and urine by high-performance liquid chromatography

The determination of quinine, (3S)-3-hydroxyquinine, 2'-quininone and (10R) - and (10S)-10, 11-dihydroxydihydroquinine in plasma and urine samples is d escribed. This is the first time the R and S configurations have been corre ctly assigned to the two metabolites of 10,11-dihydroxyquinine. One hundred microliter-plasma samples were protein precipitated with 200 mul cold meth anol. Urine samples were 10-100X diluted and then directly injected into th e HPLC. A reversed-phase liquid chromatography system with fluorescence det ection and a Zorbax Eclipse XDB phenyl column and gradient elution was used . The within and between assay coefficients of variation of the method for quinine and its metabolites in plasma and urine was less than 13%. The lowe r limit of quantitation was in the range of 0.024-0.081 muM. (C) 2001 Elsev ier Science B.V. All rights reserved.