ABSTRACT
OBJECTIVE: To develop a sensitive and specific reverse-phase high-performance liquid chromatography (RP-HPLC) method to determine propofol in follicular fluid. METHODS: Thymol was added into follicular fluid samples as the internal standard, and the samples were then precipitated with methanol. After centrifugation at 20000 r·min-1 for 15 min, 20 μL of supernatant was directly injected into an Agilent Extend-C18 column (4.6 mm×250 mm, 5 μm). The mobile phase was composed of methanol-water (77:23). Analysis was run at a flow rate of 1.0 mL ·min-1. Fluorescence detection was applied with excitation and emission wavelengths of 276 and 310 nm, respectively. RESULTS: The calibration curves had good linearity in the range of 0.108-5.4 mg·L-1. The linear regression equation was A=0.2074ρ-0.0012(r=0.9993). The limits of detection and quantity proved to be 54 and 108 μg·L-1, respectively. The method recoveries for low, intermediate and high concentrations were 117.9%, 101.7% and 99.4%, respectively. The RSDs of inter-day assay were 4.10%, 1.28% and 0.20%(n=5), and intra-day assay were 4.34%, 2.33% and 0.61%(n=5), respectively. CONCLUSION: The method is accurate and convenient. It can be used to determine propofol for studying its clinical pharmacokinetics.
ABSTRACT
<p><b>AIM</b>To prepare the micelles of stearic acid-grafted chitosan oligosaccharide and investigate the drug release from micelles.</p><p><b>METHODS</b>Mediated by a 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), stearic acid (SA) was covalently attached to chitosan oligosaccharide (CSO), and the graft polymer (CSO-SA) was obtained. The critical aggregation concentration (CAC) of the CSO-SA was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe. The effect of various pH dispersed media and concentration of tripolyphosphate sodium (TPP) on the micellar size distribution and zeta-potential measured by light scattering and electrophoretic mobility, was investigated. In buffers of different pH, the release profiles of methotrexate (MTX) from micelles were evaluated.</p><p><b>RESULTS</b>The CAC value of CSO-SA in deionized water was 0.05 g x L(-1). The mean diameter of CSO-SA micelles was 26.7 nm and the zeta potential was (55.9 +/- 0.1) mV. With the increase of TPP concentration, the size and MTX encapsulation of CSO-SA micelles increased, while the zeta-potential decreased. With the decrease of pH value of dispersed media, the size and zeta-potential of CSO-SA micelles increased, and the MTX encapsulation in CSO-SA micelles decreased. While the enhancement of drug release from the micelles was observed.</p><p><b>CONCLUSION</b>The graft polymer of CSO-SA provides polymeric micelles, which possessed a low CAC value in aqueous media. The drug release in vitro from CSO-SA micelles was affected by the pH of delivery media.</p>