Simultaneous determination of four phytoecdysteroids by LC-MS/MS: application to a comparative pharmacokinetic study in normal and adjuvant arthritis rats after oral administration of C. officinalis Kuan phytoecdysteroids extract

Abstract

1.Method validation 1.1 Selectivity and SpecificitySelectivity was ascertained by comparing chromatograms of seven different batches of blank rat samples and corresponding blank plasma samples spiked with the four compounds and I.S., and the plasma samples from the rats after oral administration of the C. officinalis Kuan phytoecdysteroids extract were obtained. Specificity is the ability of analytical methods to distinguish and quantify analytes in the presence of other components. Linearity and LLOQCalibration curves were generated by assaying standard plasma samples at seven concentration levels and the linearity was constructed by using the plot of the peak area ratios of each analyte to its corresponding IS versus the nominal concentration of the calibration standard. The LLOQ was defined as the lowest concentration of the standard curve with the S/N greater than 10. Precision and accuracyThe intra-day and inter-day precision and accuracy of the method were evaluated for three consecutive days by analyzing samples of LLOQ and QC samples at four concentration levels (six replicates per concentration level), respectively. The concentrations of the QC samples were measured by a standard calibration curve and analyzed on the same day. Mean concentrations and relative standard deviations (RSD) were defined using validation sample values and the precision of intra-day and inter-day