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Leeds, United Kingdom

Xiang Q.,Wuhan University | Hashi Y.,COE Limited | Chen Z.,Wuhan University
Journal of Separation Science | Year: 2016

A rapid and sensitive ultra high performance liquid chromatography with electrospray ionization tandem mass spectrometry method was developed and validated for the simultaneous determination of eight major active components (magnoflorine, menisperine, 20-hydroxyecdysone, cepharanthine, columbamine, jatrorrhizine, columbin, and palmatine) in Radix Tinosporae. The separation was performed on an InterSustainSwift C18 column (1.9 μm, 2.1 id × 100 mm) at 40 °C with a gradient elution. A mixture of acetonitrile and methanol (v/v = 1:1) and ammonium acetate buffer (25 mmol/L ammonium acetate with 0.2% formic acid) were used as mobile phases, and the flow rate was set at 0.4 mL/min. The recovery was tested in real samples and calculated to be 86.97-111.28%, and all the compounds showed good linearity (r > 0.998) in relatively wide concentration ranges. The developed method was applied to the determination of eight active compounds in real herb samples, which were collected from four different places. It has been demonstrated that the proposed method has great potential for the quality control of the traditional Chinese medicine Radix Tinosporae. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Cai B.-D.,Wuhan University | Zhu J.-X.,Wuhan University | Gao Q.,Wuhan University | Luo D.,COE Limited | And 2 more authors.
Journal of Chromatography A | Year: 2014

A rapid method was developed for determination of endogenous cytokinins (CKs) based on magnetic solid-phase extraction (MSPE) followed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). We illustrated the hydrophilic character of bare Fe3O4 nanoparticles that were directly used as a MSPE sorbent for rapid enrichment of endogenous CKs from complex plant extract. To the best of our knowledge, this is the first report of bare Fe3O4 directly used as efficient extraction sorbent to enrich target CKs based on hydrophilic interaction. Under the optimized conditions, a rapid, sensitive and high-throughput method for the determination of 16 CKs was established by combination of MSPE with UPLC-MS/MS. Good linearity was obtained with correlation coefficients (r) from 0.9902 to 0.9998. The limits of detection (LODs) and quantification (LOQs) ranged from 1.2pgmL-1 to 391.3pgmL-1 and 4.1pgmL-1 to 1304.3pgmL-1, respectively. 16 CKs could be successfully determined in spiked sample with 80.6-117.3% recoveries and the relative standard deviations (RSDs) were less than 16.6%. Finally, 10 endogenous CKs were successfully quantified in 50mg Oryza sativa sample using the developed MSPE-UPLC-MS/MS method. © 2014 Elsevier B.V. Source


Gao Q.,Wuhan University | Lin C.-Y.,Wuhan University | Luo D.,COE Limited | Suo L.-L.,Wuhan University | And 2 more authors.
Journal of Separation Science | Year: 2011

A novel magnetic material Fe3O4/SiO 2/P(MAA-co-VBC-co-DVB) was prepared via the hypercrosslinking of its precursor which was produced via precipitation polymerization of methacrylic acid (MAA), vinylbenzyl chloride (VBC), and divinylbenzene (DVB) in the presence of Fe3O4/SiO2 submicrospheres with the surface containing abundant reactive double bonds. The resultant sorbent was characterized by scan electron microscopy, N2 adsorption, and Fourier transform infrared spectroscopy. It was found that this material had remarkable features such as large surface area (500m2/g) and pore volume (0.32 cm3/g), as well as desirable chemical composition (including hydrophobic and ion-exchange moieties). Taking advantages of the Fe 3O4/SiO2/P(MAA-co-VBC-co-DVB), a magnetic SPE (MSPE) coupled with capillary electrophoresis (CE) method was developed for the determination of illegal drugs in urine samples. The extraction time could be clearly shortened up to 3 min. The recoveries of these drug compounds were in the range of 84.0-123% with relative standard deviations ranging between 1.7 and 10.5%; the limit of detection was in the range of 4.0-6.0 mg/L. The proposed method is simple, effective, and low-cost, and provides an accurate and sensitive detection platform for abused drug analysis. © 2011 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim. Source


Gao Q.,Wuhan University | Luo D.,Wuhan University | Luo D.,COE Limited | Bai M.,Wuhan University | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2011

In this study, a nanocomposite of polypyrrole-coated magnetite nanoparticles (denoted as MNPs/PPy) was prepared and employed as magnetic solid-phase extraction (MSPE) sorbent for extraction of estrogens from milk samples. Because the polypyrrole coating possessed a highly π-conjugated structure and hydrophobicity, MNPs/PPy showed excellent performance for the estrogen extraction. Estrogens could be captured directly by MNPs/PPy from milk samples without protein precipitation. Moreover, the extraction could be carried out within 3 min. Thus, a rapid, simple, and effective method for the analysis of estrogens in milk samples was established by coupling MNPs/PPy-based MSPE with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The limits of detections for estrogens investigated were in the range of 5.1-66.7 ng/L. The recoveries of estrogens (concentration range of 0.5-20 ng/mL) from milk samples were in the range of 83.4-108.5%, with relative standard deviations ranging between 4.2 and 15.4%. © 2011 American Chemical Society. Source


Ma W.,Wuhan University | Fu S.,Wuhan University | Hashi Y.,COE Limited | Chen Z.,Wuhan University
Journal of Agricultural and Food Chemistry | Year: 2013

A GC/MS method with monolithic material sorptive extraction (MMSE) pretreatment was developed to determine contents of the enantiomers of jasmonic acid and methyl jasmonate in flowers. To optimize MMSE extraction, several MMSE parameters were investigated, including extraction temperature, extraction time, and extraction solvent. Under the optimal conditions, extraction efficiency was good. Using the selected-ion monitoring mode, the limit of detection (LOD, S/N = 3) for methyl jasmonates was 0.257 ng/mL. The limit of quantitation (LOQ, S/N = 10) was 0.856 ng/mL. The linearity range was 1-100 ng/mL. The average recovery of methyl jasmonate at lower concentration was 116.8% (2 ng/mL). The relative standard deviation of methyl jasmonate contents determined within the linear range of detection was less than or equal to 15% of the mean determined level. The proposed method is rapid, sensitive, and competently applied to the determination of jasmonic acid and methyl jasmonate enantiomers in flowers. © 2013 American Chemical Society. Source

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