Biomedical subjects

Yanwei Wu

Publications and source records attributed to Yanwei Wu.

3 recordsLinked to original sources

PubMed2006

Stochastic resonance is applied to quantitative analysis for weak chromatographic signal of roxithromycin in beagle dog plasma.

Based on the theory of stochastic resonance, the signal to noise ratio (SNR) of HPLC/UV chromatographic signal of roxithromycin is enhanced by cooperation of signal, noise and nonlinear system. A simple new method for the determination of low concentration of roxithromycin in beagle dog plasma is presented. Using signal enhancement by stochastic resonance, this method extends the limit of quantitation from the reported 0.5 to 0.1 microg/ml. During validation of the new method, HPLC/MS was used as a comparison technique. The results indicate that the recovery and low concentrations of roxithromycin in beagle dog plasma were equivalent between the two methods (P>0.05). Stochastic resonance may be a promising tool for improving detection limits in trace analysis.

Animals↗

PubMed2005

Preparative SEC column packed with microporous particles prepared from cellulose.

New microporous particles with large pore size (mean pore diameter of 820 nm) are successfully prepared from a mixture of cellulose and konjac glucomannan (RC-KGM3) in 1.5 M NaOH-0.65 M thiourea aqueous solution by coagulating with 5 weight percentage (wt%) CaCl(2), and then 2 wt% HCl aqueous solution. A preparative size-exclusion chromatographic (SEC) column packed with the gel particles is used for the fractionation of a dextran in water. The exclusion limit and fractionation range of the stationary phase are molecular masses of 125 yen 104 g/mol and 5.6 yen 104 to 125 yen 104 g/mol, respectively. The dextran [dextran 50, weight-average molecular mass (M(w)) = 40.1 yen 104 g/mol, polydispersity index (d) = 3.5] is fractionated by the preparative SEC column to obtain six fractions, and four of them are refractionated twice by the same preparative SEC column. The refractionated samples F-3-3 and F-4-3 are characterized by analytical SEC combined with laser light scattering and light scattering to obtain M(w) of 91.8 and 61.9 yen 104 g/mol, as well as d of 1.3 and 1.4, respectively. The results indicate that the fractions having narrow molecular mass distribution are satisfactorily prepared with the SEC column. The described SEC column can be successfully used to fractionate polymers in aqueous solution.

Cellulose↗

PubMed2005

Determination of nifuratel in human plasma by HPLC and study on its pharmacokinetics.

A simple and sensitive reversed-phase high-performance liquid chromatography method using UV detection is established for the determination of nifuratel in human plasma and applied to a study of its pharmacokinetics. Plasma samples are extracted with ethyl acetate. A C(18) column and a mobile phase of 0.01 M (pH 7) phosphate buffer (KH(2)PO(4)) and acetonitrile (61:39, v/v) are used. Analysis is run at a flow rate of 1.0 mL/min with the detector operated at a wavelength of 367 nm. The calibration curve is linear over a concentration range of 0.2-40 ng/mL with a correlation coefficient of 0.9996. The limit of detection is 0.1 ng/mL. The mean absolute recovery value is greater than 80%. The intraday precision (relative standard deviation) ranges from 1.89% to 7.32%, and the interday precision ranges from 1.71% to 7.83%. The results show that the area under the plasma concentration-time curve, time to maximum observed plasma concentration, maximum concentration reached in the concentration profile, and elimination half-life between the testing tablets and reference tablets have no significant difference (P > 0.05). Relative bioavailability is 104.0% +/- 16.5%.

Chromatography, High Pressure Liquid↗