ABSTRACT
A new method based on ultraperformance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) was developed for the simultaneous determination of 22 endocannabinoids(eCBs) and relevant compounds in ovariectomized rat plasma. After being extracted by solid-phase column(SPE), the plasma samples were detected by using UPLC-MS/MS. Analysis was carried out with ACQUITY UPLC BEH C₁₈ column. The mobile phase was 0.1% acetic acid solution(A)-acetonitrile and isopropanol(9∶1, B) for the gradient elution. In the positive ion multiple reaction monitoring(MRM) mode, deuterated reagents were taken as standard alternatives to calculate recoveries and simultaneously quantify 22 endocannabinoids. The established method provided a good linearity for the 22 eCBs, and their linearly dependent coefficients were all higher than 0.99. The limits of quantitation(LOQs) ranged from 0.089 6 to 1.965 2 nmol•L-1. Relative recoveries of 5 deuterated surrogates ranged between 11.40% and 129.9%. The repeatability study results showed that RSD was all less than 8.0%. The established method could be used to analyze PGF2a EA, AEA and other endogenous cannabinoids in plasma samples of ovariectomized rats. In summary, this method was proved to boast a high sensitivity, repeatability and practicability, and thus could be used in rat plasma lipid metabolomics study.
ABSTRACT
A comprehensively comparison of the chemical profiles between sun-drying BJ (NBJ) and sulfur-fumigated BJ (SBJ) was conducted by HPLC analysis and the discrepant peaks were identified or tentatively assigned by HPLC-ESI-MSn. A total of 32 chemical components were used for qualitative comparison. Meanwhile, a quantitative comparison of BJwere conducted by HPLC analysis and determining seven compounds from 3 NBJ and 3 SBJ samples dramatic chemical changes were found. After sulfur fumigation, the contents of flavonoids glycosides and phenolic acids were remarkably reduced, but the contents of flavonoids aglycones were significantly increased. Multivariate statistics, including principle component analysis (PCA) and partial least squares discriminate analysis (PLS-DA) were used to investigate the potential damaging effect of sulfur-fumigating process. The PCA score plots showed six samples were clearly classified into the sun-drying and sulfur-fumigating groups. And according to VIP >1, the most important chemical markers were apigenin, luteolin and 3,5-dicaffeoylquninic acid which could be used to distinguish NBJ and SBJ samples. Combining the results of qualitative and quantitative analysis, it showed that the sulfur fumigation has a significant effect on BJ.