UPLCeMS/MS for the determination of azilsartan in beagle dog plasma and its application in a pharmacokinetics study

The purpose of the study is to develop an ultra performance liquid chromatographytandem mass spectrometry(UPLCeMS/MS)to determinate the concentration of azilsartan in the dog plasma.After precipitated by methanol,the plasma sample containing azilsartan and diazepam(internal standard,IS)was determined by UPLCeMS/MS.The mobile phase consisted of acetonitrile-water was pumped at a flow rate of 0.3 ml/min in gradient elution.Kinetex 2.6 m XB-C18 column(50
2.1 mm,100Å;Phenomenex,USA)were used for LC separations.The column temperature was 30℃ and the injection volume was 5 ml.The electrospray ionization(ESI)and multiple reaction monitoring(MRM)were applied at the transitions of m/z 457/279(azilsartan)and m/z 285/193(diazepam),respectively.The developed method was identified a good linearity over a concentration range of 2.5e5000 ng/ml.The lower limit of quantitation(LLOQ)was 2.5 ng/ml.The intraday and inter-day precision(relative standard deviation,RSD%)were less than 10%and accuracy(relative error,RE%)was less than 5%at three quality control levels.The extraction recovery of azilsartan at three quality control levels were 82.41±0.68%,98.66±11.00%,102.43±0.82%.And the recovery for IS(100 ng/ml)was 91.75±0.54%.A validated UPLCeMS/MS method was firstly developed for the quantification of azilsartan in dog plasma and it was applied to the pharmacokinetics study.

Quantitative determination of isradipine in dog plasma by an ultra performance liquid chromatographyetandem mass spectrometry method

A simple,sensitive and specific ultra performance liquid chromatographyetandem mass spectrometry(UPLCeMS/MS)method was developed for the analysis of isradipine in dog plasma.After extracted with organic solvent,dog plasma samples were analyzed on an Acquity UPLC BEH C18 column interfaced with a triple quadrupole tandem mass spectrometer in positive electrospray ionization mode.Acetonitrile:water:formic acid(80:20:0.3,v/v/v)was used as the mobile phase at a flow rate of 0.2 ml/min.The chromatographic run time of each sample was 1.4 min.The calibration curve in plasma was linear in the range of 0.1e40.0 ng/ml.The intra-and inter-day precision was within 13.5%in terms of relative standard deviation(RSD%)and the accuracy was required to be 96.5%e98.4%.The validated UPLCeMS/MS method was successfully applied in a pharmacokinetic study of controlledrelease isradipine in dogs.

Comparative analysis of twenty-five compounds in different parts of Astragalus membranaceus var.mongholicus and Astragalus membranaceus by UPLC-MS/MS

As a traditional Chinese medicine,the root of Astragalus membranaceus var.mongholicus(AMM) or A.membranaceus(AM) has been widely used in China and other Asian countries for thousands of years.Till now,the flavonoids,phenolic acids and saponins are considered as the main active components contributing to their therapeutic effect in these plants.In order to clarify the distribution and contents of these compounds in different organs of these plants,a rapid and sensitive analytical method for simultaneous determination of 25 active compounds including seven types(i.e.dihydroflavones,isoflavane,isoflavones,flavones.pterocarpans,phenolic acid and saponins) within 10 min was established using ultra-pressure liquid chromatography coupled with tandem mass spectrometry(UPLC-MS/MS).Then,the established method was fully validated and successfully applied to the determination of the contents of these analytes in different parts(root,rhizome,stem,leaf and flower) of AMM and AM.The results indicated that the contents of the same type of compounds in two different species plants were significantly different.Moreover,the obvious differences were also found for the distribution and contents of different type of compounds in five organs of the same species.The present study could provide necessary information for the rational development and utilization of AMM and AM resource.