Objective: To establish an HPLC-MS/MS method for the determination of hypericin in rat plasma. Methods: The sample was analyzed by HPLC-MS/MS after the addition of internal standard and then protein precipitation using acetonitrile. The sepa-ration was carried out on an Ultimate C18 column (150 mm × 2. 1 mm,5. 0 μm). The mobile phase was composed of acetonitrile∶ 5 mmol·L-1 ammoniumacetate (containing 0. 1% formic acid) (90∶10) at a flow rate of 0. 5 ml·min-1 under 35℃. The detection was performed with multiple teactions monitoring ( MRM) using an electrospray ionization ( ESI) . The precursor/product ion transitions were monitored at m/z 503. 2→m/z 405. 1 for hypericin and m/z 355. 0→m/z 41. 9 for the internal standard pioglitazone ( anion mode). Results:The good linearity of hypericin was obtained within the range of 0. 1-13. 2 ng·ml-1. The correlation coefficient was more than 0. 99 and the lower limit of quantification was 0. 1 ng·ml-1. The extraction recovery was within the range of 84. 19%-98. 71%. The precision of intra-and inter-day was below 18. 47%. Conclusion: The method is fast, sensitive and accurate, which provides research basis for the clinical further study of hypericin.

Objective:To establish an LC–MS/MS method for the determination of the active metabolite(SN-38) and secondary metabolite(SN-38G) of irinotecan in rat liver microsomes incubation system, and optimize the incubation conditions. Methods:Meth-anol was selected to precipitate protein in the samples, and then the concentrations were analyzed by LC–MS/MS. All the separation was carried out on a ZORBAX Eclipse XDB-C18 column(2. 1 mm × 50 mm, 3. 5 μm) with the mobile phase of acetonitrile – water (containing 0. 1% formic acid) (23 :77) at a flow rate of 0. 3 ml·min-1. The mass spectrometer was operated with multiple reac-tions monitoring ( MRM) using electrospray ionization ( ESI) . The incubation conditions were optimized by single factor design. Re-sults:SN-38 and SN-38G showed a good linearity ( r≥0. 9972) respectively within the range of 2. 3-920 ng·ml-1 and 2. 5-1000 ng ·ml-1. The intra-and inter-day RSD was below 14. 6%(n=6). The average recovery was within the range of 74. 1%-123. 4% with RSD below 13. 5% (n=6). The optimal incubation conditions were as follows:the concentration of liver microsomal protein was 0. 3 mg·ml-1 and the incubation time was 30 min. Conclusion:The method is rapid, sensitive and accurate in the quantification of SN-38 and SN-38G in the incubation system,which provides methodological basis for the activity determination of UGT1A1 enzyme in vitro.

A simple and sensitive liquid chromatographic method was developed for quantification of cefotetan disodium (CTT), a semi-synthetic cephamycin antibiotic, in human plasma. CTT and the internal standard chloramphenicol were extracted from plasma by a simple one-step protein precipitation with 35% (v/v) perchloric acid. Separation was carried out on a reverse-phase C18 column with a mobile phase of acetonitile-water containing 0.5% (v/v) phosphoric acids (20:80, v/v) at a flow rate of 1.0 mL/min. The column effluent was monitored by UV detection at 300 nm. The column temperature was maintained at 40°C. This method demonstrated good linearity in the range of 0.525-300.0 μg/mL, with correlation coefficients greater than 0.99. The limit of quantification (LOQ) was 0.525 μg/mL in human plasma. Intra- and inter-day precisions were less than 6.63% in terms of relative standard deviation (RSD). The accuracy, when expressed by the bias, ranged from 0.57% to 4.04%. The mean extraction recovery of CTT was higher than 40.94%. The method was found to be precise, accurate, and specific for CTT quantitative analysis, and was successfully applied for a pharmacokinetic study of CTT after a single intravenous dose of 1.0 g of CTT in healthy Chinese subjects.

A simple and sensitive liquid chromatographic method was developed for quantification of cefotetan disodium (CTT), a semi-synthetic cephamycin antibiotic, in human plasma. CTT and the internal standard chloramphenicol were extracted from plasma by a simple one-step protein precipitation with 35% (v/v) perchloric acid. Separation was carried out on a reverse-phase C18 column with a mobile phase of acetonitile-water containing 0.5% (v/v) phosphoric acids (20:80, v/v) at a flow rate of 1.0 mL/min. The column effluent was monitored by UV detection at 300 nm. The column temperature was maintained at 40°C. This method demonstrated good linearity in the range of 0.525-300.0 μg/mL, with correlation coefficients greater than 0.99. The limit of quantification (LOQ) was 0.525 μg/mL in human plasma. Intra- and inter-day precisions were less than 6.63% in terms of relative standard deviation (RSD). The accuracy, when expressed by the bias, ranged from 0.57% to 4.04%. The mean extraction recovery of CTT was higher than 40.94%. The method was found to be precise, accurate, and specific for CTT quantitative analysis, and was successfully applied for a pharmacokinetic study of CTT after a single intravenous dose of 1.0 g of CTT in healthy Chinese subjects.
Cefotetan ; blood ; pharmacokinetics ; Chromatography, Liquid ; methods ; Humans