RESUMO
OBJECTIVE: To establish an HPLC method for the simultaneous determination of butorphanol tartrate, dextroisomer and benzethonium chloride which works as the bacteriostatic agent in butorphanol tartrate injection on a cyclodextrin chiral column. METHODS: The HPLC analysis was performed on an Astec Cyclobond II cyclodextrin chiral column (4.6 mm×250 mm, 5 μm), with mobile phase consisting of 0.05 mol·L-1 ammonium acetate solution (pH was adjusted to 4.1 by acetic acid) and acetonitrile using gradient elution at a flow rate of 1.0 mL·min-1. The detection wavelength was set at 280 nm. RESULTS: The method showed good linearity for the three components to be measured. The linear ranges were 0.04-2.0 mg·mL-1 for butorphanol tartrate (r=0.999 9), 0.01-2.0 mg·mL-1 for dextroisomer (r=1.000 0), and 0.02-1.0 mg·mL-1 for benzethonium chloride (r=0.999 9), respectively. The average recoveries were 100.2%, 100.7%, and 99.4%, respectively. CONCLUSION: The method is simple, accurate and reproducible. It can be used for the quality control of butorphanol tartrate injection.
RESUMO
A selective, sensitive and high throughput liquid chromatography-tandem mass spectro-metry (LC-ESI-MS/MS) method has been developed for separation and quantification of metoprolol enantiomers on a chiral Lux Amylose-2 (250 mm×4.6 mm, 5 mm) column. Solid phase extraction of (S)-(-)- and (R)-(t)-metoprolol and rac-metoprolol-d6 as an internal standard (IS) was achieved on Lichrosep DVB HL cartridges employing 200 mL human plasma. Both the analytes were chromatographically separated with a resolution factor of 2.24 using 15 mM ammonium acetate in water, pH 5.0 and 0.1% (v/v) diethyl amine in acetonitrile (50:50, v/v) as the mobile phase within 7.0 min. The precursor-product ion transitions for the enantiomers and IS were monitored in the multiple reaction monitoring and positive ionization mode. The method was validated over the concentration range of 0.500-500 ng/mL for both the enantiomers. Matrix effect was assessed by post-column analyte infusion experiment and the mean extraction recovery was greater than 94.0% for both the enantiomers at all quality control levels. The stability of analytes was evaluated in plasma and whole blood under different storage conditions. The method was successfully applied to a clinical study in 14 healthy volunteers after oral administration of 200 mg metoprolol tablet under fasting conditions. The assay reproducibility is shown by reanalysis of 68 incurred samples. The suitability of the developed method was assessed in comparison with different chromatographic methods developed for stereoselective analysis of metoprolol in biological matrices.