ABSTRACT
To ensure the safety of the commercially available chenpi, a convenient and fast analytical method was developed for the determination of 133 pesticide residues in chenpi using gas chromatography-tandem mass spectrometry (GC-MS/MS). In this study, different extraction solvents, redissolution solvents and adsorbents were tested according to the recovery and purification effect to obtain a modified QuEChERS method. The samples were extracted with acetonitrile. During the clean-up step, octadecyl-modified silica (C18) and graphitized carbon black (GCB) were selected, and aminopropyl (NH2) was used instead of primary secondary amine (PSA) because of its weaker ion exchange capacity which had little effect on the recovery of ditalimfos. Samples were quantified by matrix-matched calibration with internal stan-dards. All pesticides showed good linearity in the respective range, both with values of r2 >0.99. The average recoveries of the pesticides spiked samples ranged from 70.0％ to 112.2％ with the RSDs of 0.2％–14.4％. The modified QuEChERS method was validated and applied to twenty real samples. Five pesticides were found in eight batches, but no pesticide exceeded the maximum residue limits (MRL, MRL reference to European commission).
ABSTRACT
An acute myocardial infarction rat model was established by ligation of the left ventricular coronary artery.Plasma samples of rats were collected and analyzed by ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) to study the myocardial protection mechanism of compound Danshen dropping pill (CDDP).After principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), 22 metabolites were identified as potential biomarker of AMI.Furthermore, CDDP had remarkable effect on AMI rats.p-Tolyl sulfate, hippuric acid, equol 7-O-glucuronide, lysoPC(16∶0), cholic acid, oleamide, palmitic amide and SM(d18∶1/16∶0) were significantly changed in treatment group.The results showed that CDDP had a very good myocardial protection effect on AMI rats, and might influence the pathways of phenylalanine metabolism, glycerophospholipid metabolism, fatty acid metabolism, primary bile acid biosynthesis and Sphingolipid metabolism.
ABSTRACT
Ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS) was developed to identify the absorbed parent components and metabolites in rat bile, plasma and urine after oral administration of Radix Paeoniae Alba extract (RPAE). A total of 65 compounds were detected in rat bile, plasma and urine samples, including 11 parent compounds and 54 metabolites. The results indicated that glucuronidation, hydroxylation and methylation were the major metabolic pathways of the components of RPAE. Furthermore, the results of this work demonstrated that UPLC-Q-TOF/MS combined with MetaboLynx? software and mass defect filtering (MDF) could provide unique high throughput capabilities for drug metabolism study, with excellent MS mass accuracy and enhanced MSE data acquisition. With the MSE technique, both precursor and fragment mass spectra can be simultaneously acquired by alternating between high and low collision energy during a single chromatographic run.