Isoentropic and Isoenthalpic Temperatures of Protein Unfolding in Hydrophobic Interaction Chromatography

The thermal behaviors of five proteins in hydrophobic interaction chromatography （HIC） were investigated in the temperature range from 0 to 50℃. The thermodynamic parameters （△H°,△S°, △Cp°and △G°） of these proteins in the process of retention and unfolding were determined. The existence of enthalpy and entropy convergence with temperature was confirmed. The differences of the isoentropic and isoenthalpic temperatures for protein unfolding in HIC system from the traditional solution were elucidated.

Simultaneous Determination of Two Types of Active Components with Different Physicochemical Properties in Kushen by HPLC-UV

A simple, reliable and accurate high performance liquid chromatography(HPLC) coupled with a UV detector at varied wavelength was developed for the quantitation of two types of anti-carcinogenic compounds, namely, Kushen alkaloids(KS-As) and Kushen flavonoids(KS-Fs), in Kushen. Their remarkable difference in physicochemical properties was circumvented by integrated optimization of column and mobile phase. The separation was achieved on an alkaline-resisting C18 column via gradient elution with acetonitrile(ACN) and 0.025%(volume ratio) diethylamine(DEA) in water as mobile phase. The flow rate was 0.7 mL/min, and the column temperature was maintained at 35 °C. UV detection wavelength was set at 225 nm to monitor KS-As, and then changed to 335 nm for KS-Fs at 26th min, which was kept for 30 min before returning to the original wavelength. All the calibration curves show good linearity(r20.999) within test ranges. The intra- and inter-day precision values of these components were less than 3.82%, and the average recovery rates obtained were in a range of 97.24%―102.64% for all the samples with RSD below 3.94%. This assay was successfully applied to determining the major active components in commercial herbal samples of Kushen. Moreover, the possible relationship between sample and the geographical region was visualized based on the contents of the 6 compounds in the light of principal component analysis(PCA). The results suggest that the proposed method facilitates the quality control of Kushen.

Development and Validation of a HPLC Method for Determination of Flavone Glycoside-Camellianin B in Cephalotaxus Sinensis

A simple,rapid and sensitive method for the quantification of camellianin B in Cephalotaxus sinensis（C.sinensis）a natural plant with anti-hyperglycemic effect,was developed and validated by reversed phase liquid chromatography.Chromatographic separation was achieved on a C18 column and an isocratic elution was carried out at a flow-rate of 1.0 mL·min-1 with the acetonitrile-water containing0.1%formic acid（19∶81,v/v）.The detection wavelength was set at 330 nm.The calibration curve was linear over the concentration range of 0.25-50μg·mL-1 with correlation coefficients larger than0.999 5.The limit of detection and limit of quantification were 0.09μg·mL-1and 0.25μg·mL-1,respectively.The precisions and accuracy for all samples were acceptable.The validated method has been successfully applied for the quantification of camellianin B in C.sinensis harvested in different months and may also be used as the quality evaluation of this herb medicine.

LC-ELSD analysis for simultaneous determination of five components in the Xue-Fu-Zhu-Yu capsules

A reliable and accurate liquid chromatography with evaporative light scattering detection(LC-ELSD)method was developed for simultaneous determination of five constituents in Xue-Fu-Zhu-Yu capsule,a widely used prescription of traditional Chinese medicine(TCM).The chromatographic separation was performed on a Symmetry C_(18)column(150 mm×4.6 mm,5.0μm)using gradient elution of acetonitrile and water(containing 1.0%acetic acid).The flow rate was 0.6 mL/min and the temperature of column was 30℃.A good linearity correlation was obtained over the investigated concentration ranges.Recoveries of the five components varied from 97.31%to 99.84%(RSD<4.0%).The validated method was successfully applied to the quality assessment of Xue-Fu-Zhu-Yu capsule.