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Glycosylated flavonols were characterized in the extracts of Rhamnus petiolaris and Rhamnus utilis , by high performance liquid chromatography coupled with photo diode and mass spectrometric detectors (HPLC-PDA-MS). The main dye components are rhamnetin-3 -O -rhamninoside for R. petiolaris and kaempferol-3 -O -rhamninoside for R. utilis . Based on this information, the yellow dye used in the wall cloth in the Palace Museum can be identified as R. petiolaris or a closely related species. In the case of the wallpaper (which was under the wall cloth), the main flavonoid found was rutin, suggesting that it was dyed with buds of pagoda tree ( Sophora japonica ), a dye traditionally used in China. The results presented here provide valuable information in regard to reconstitution of the late Qing dynasty (1840–1912 AD) wall coverings. In addition to HPLC-PDA-MS analysis, surface enhanced Raman spectroscopy (SERS) was used to tentatively identify yellow dyes in the two historical artifacts. Only a 1 mm length of single fiber, obtained from each Qing dynasty sample, was needed for comparison with the SERS data of dye references. This ultra-sensitive method is suitable for situations where sampling is restricted to trace amounts. [ABSTRACT FROM AUTHOR]

A sensitive and accurate liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for determination of tulobuterol in rat plasma for the first time. Plasma samples were extracted by liquid–liquid extraction method with methyl tert -butyl ether and the analyte and clenbuterol (IS) were separated on a Venusil MP C 18 column (100 mm × 2.1 mm, 3 μm) using 0.1% formic acid–water–methanol as mobile phase, with a runtime of 5 min. The analyte was detected in multiple reaction monitoring (MRM) mode with positive electrospray ionization. Transitions of m / z 228.2 → 154.0 for tulobuterol and m / z 277.1 → 203.0 for the clenbuterol were monitored. The linear range was 0.5–100 ng/ml ( r = 0.9967) for tulobuterol with the lower limit of quantitation of 0.5 ng/ml. The intra-day and inter-day precisions were less than 10.3% for the analyte and the accuracy was less than −8.6%. The RSD of matrix effect and recovery yield were within ±15% of nominal concentrations and tulobuterol was stable during stability studies. The validated method has been successfully applied to a pharmacokinetic study of three doses of tulobuterol patch in rats for the first time. [ABSTRACT FROM AUTHOR]