Xiaohua Xiao

Sun Yat-Sen University, Shengcheng, Guangdong, China

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Publications (22)63.11 Total impact

  • Xiaohua Xiao · Kuanglin Yan · Xianfang Xu · Gongke Li
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    ABSTRACT: Ritodrine has similar skeleton structure to ractopamine and it was selected as the dummy-template molecule to synthesize the molecular imprinted polymers (MIPs). The MIPs exhibited better selectivity to ractopamine than to the dummy-template molecule: the imprint factor for ractopamine was 8.9, while 7.6 for ritodrine. The MIPs were used as sorbents in solid-phase extraction for selective enrichment of ractopamine, and some key parameters were optimized. After that, a rapid surface-enhanced Raman spectroscopy method was developed for analysis of ractopamine and isoxuprine in pig tissue samples. Under the optimal conditions, good linearity was achieved in the range of 20.0-200.0μg/L for ractopamine and isoxsuprine at 842cm(-1) and 993cm(-1), respectively. The limits of detection were 3.1-4.3μg/L, which were lower than the maximum allowed by U. S. Food and Drug Administration. The recoveries of ractopamine and isoxsuprine were 72.4-79.7% and 71.0-78.2% for the spiked pork and pig liver, respectively, while the relative standard deviations ranging from 7.4% to 13.0%. The results suggest that the proposed method is sensitive and selective, and it has good potential on the quantitative analysis of trace amounts of β-agonists in complex samples. Copyright © 2015 Elsevier B.V. All rights reserved.
    Talanta 02/2015; 138. DOI:10.1016/j.talanta.2015.02.003 · 3.51 Impact Factor
  • Qianchun Zhang · Gongke Li · Xiaohua Xiao
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    ABSTRACT: Heterocyclic amines (HAs) are considered as potential mutagens and carcinogens, and are found in trace quantities (ng/g level) in food samples. Therefore, it is important to develop a selective and effective method to determine trace HAs in complex matrices. In this study, acrylamide-modified graphene (AMG) was successfully synthesised and showed good stability and permeability in aqueous and organic phases. AMG was used as an efficient adsorbent in the online micro-solid-phase extraction (μ-SPE) of trace HAs. The enrichment factors of the AMG μ-SPE column were determined as 78-166 for six HAs. An online method based on AMG μ-SPE coupled to high-performance liquid chromatography was developed. The limits of detection ranged from 0.70 to 2.5ng/L. Trace HAs in spicy salted duck, baked fish, and fried chicken samples were determined and the concentrations of 2-amino-3-methylimidazo[4,5-f]quinoine, 2-amino-3,4-dimethylimidazo[4,5-f]quinoine, and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline in these samples were 4.7-37.3, 8.1-15.4, and 43.3-109ng/g, respectively. The recoveries for the six HAs ranged from 65.9% to 118%, and the relative standard deviation (RSDs) were less than 10.8%. The proposed online method was sensitive, reliable, and convenient for the analysis of trace HAs in food samples.
    Talanta 01/2015; 131:127–135. DOI:10.1016/j.talanta.2014.07.080 · 3.51 Impact Factor
  • Qianchun Zhang · Xiaohua Xiao · Gongke Li
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    ABSTRACT: Heterocyclic amines (HAs) are considered as highly potential mutagens and carcino- gens in cooked meat products. Efficient sample pretreatment as well as sensitive analytical method is very important for the determination of HAs in complex samples. In this paper, some sample pretreatment methods such as solvent extraction, solid-phase extraction, and solid- phase microextraction as well as analytical methods including liquid chromatography, and liquid chromatography-mass spectrometry are reviewed; The progress of HAs analysis is also prospected. A total of 51 references are cited.
  • Qianchun Zhang · Xiaohua Xiao · Gongke Li
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    ABSTRACT: A novel porous molecularly imprinted monolithic capillary column (MIMCC) based on ternary porogen was synthesized by in situ technique with sulfaquinoxaline as the template molecule. The characteristics of the MIMCC were investigated by scanning electron microscopy, infrared spectrum, thermogravimetric analysis and solvent resistance test. The saturated adsorption amount of sulfaquinoxaline on MIMCC was 2.7 times over that on the non-imprinted monolithic capillary column (NIMCC). The MIMCC also exhibited good enrichment ability to its analogs and the enrichment factors were 46-211 for five antimicrobials. High permeability and imprinting factors as well as good stability, reproducibility and long lifetime were obtained. An on-line method based on MIMCC solid-phase microextraction coupled with high-performance liquid chromatography was developed for the determination of trace antimicrobials in complex samples. The good linearity for sulfametoxydiazine, sulamethoxazole and sulfaquinoxaline was 0.05-10µg/L, the limits of detection (LODs) were 10.0-14.0ng/L. The linear range for mequindox and quinocetone were 0.10-10.0µg/L, the LODs were 20.0-27.0ng/L respectively. The recoveries were 71.0-108.2% with relative standard deviation of 1.6-8.5%, correspondingly. The results showed that MIMCC could effectively enrich antimicrobials from complex matrices. The on-line method based on MIMCC and HPLC was selective, sensitive and convenient for trace determination of antimicrobials in complex samples.
    Talanta 06/2014; 123:63–70. DOI:10.1016/j.talanta.2014.02.010 · 3.51 Impact Factor
  • Zhiquan Yuan · Xiaohua Xiao · Gongke Li
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    ABSTRACT: A simple and efficient dynamic pH junction high-speed counter-current chromatography method was developed and further applied to the online extraction, separation and purification of alkaloids from Stephania cepharantha by coupling with microwave-assisted extraction. Mineral acid and organic base were added into the mobile phase and the sample solution, respectively, leading to the formation of a dynamic pH junction in the column and causing focus of alkaloids. Selective focus of analytes can be achieved on the basis of velocity changes of the pH junction through appropriate selection of solvent systems and optimization of additive concentrations. The extract can be directly introduced into the HSCCC for the online extraction, separation and purification of alkaloids from S. cepharantha. Continuous separation can be easily achieved with the same solvent system. Under the optimum conditions, 6.0g original sample was extracted with 60mL of the upper phase of hexane-ethyl acetate-methanol-water (1:1:1:1, v/v/v/v) containing 10% triethylamine under 50°C and 400W irradiation power for 10min, the extracts were directly separated and purified by high-speed counter-current chromatography. A total of 5.7mg sinomenine, 8.3mg 6,7-di-O-acetylsinococuline, 17.9mg berbamine, 12.7mg isotetrandrine and 14.6mg cepharanthine were obtained with purities of 96.7%, 93.7%, 98.7%, 97.3% and 99.3%, respectively. The online method provides good selectivity to ionizable compounds and improves the separation and purification efficiency of the high-speed counter-current chromatography technique. It has good potential for separation and purification of effective compounds from natural products.
    Journal of Chromatography A 07/2013; 1317. DOI:10.1016/j.chroma.2013.07.063 · 4.26 Impact Factor
  • Xiaohua Xiao · Xiaoguang Chen · Xianfang Xu · Gongke Li
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    ABSTRACT: A rapid and efficient co-precipitation assisted cloud point extraction is proposed for extraction of five estrogens [17β-estradiol (E2), estrone (E1), ethinyl estradiol (EE), diethyl stilbestrol (DES) and dihydro stilbestrol (DHS)] in environmental water and toner samples prior to high performance liquid chromatography analysis. It is based on the combination of co-precipitation with aluminum hydroxide and cloud point extraction with sodium dodecylsulfate to extract the target estrogens. Parameters affecting the extraction of target analytes including the concentration of aluminum hydroxide and sodium dodecylsulfate, extraction time, and blending types were investigated. Under optimum conditions, the enrichment factors were 31.7, 38.5, 28.2, 40.8 and 79.5 for E2, EE, E1, DES and DHS, respectively. A co-precipitation assisted cloud point extraction/high performance liquid chromatography method was developed and the limits of detection (LODs) were in the range of 0.2-0.7 μg L−1. The proposed method was successfully applied for the determination of trace estrogens in environmental water and toner samples, and the recoveries ranging from 77.3 to 104.1% with RSD of 2.0-10.4% were obtained. Moreover, the present method was compared to the previously reported methods and the extraction mechanism was also discussed. The method was rapid, sensitive and suitable for the trace estrogen analysis.
    Analytical methods 01/2013; 5(22):6376. DOI:10.1039/c3ay41372a · 1.94 Impact Factor
  • Xing Tong · Ting Zhou · Xiaohua Xiao · Gongke Li
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    ABSTRACT: A consecutive preparation method based upon accelerated solvent extraction (ASE) coupled with high-speed counter-current chromatography (HSCCC) was presented and aesculin was obtained from Cortex fraxinus. The extraction condition of ASE was optimized with response surface methodology; some significant parameters such as the solvent system and its stability, the amount of loading sample in HSCCC were also investigated. The original sample was first extracted with methanol at 105°C and 104 bar for 7 min using ASE, then the extracts were consecutively introduced into the HSCCC system and separated and purified with the same ethyl acetate/n-butanol/water (7:3:10, v/v/v) solvent system for five times without further exchange and equilibrium. About 3.1 ± 0.2 mg/g in each time and total of 15.4 mg/g aesculin with purity over 95% was isolated from Cortex fraxinus. The results demonstrated that the consecutive preparation method was time and solvent saving and high throughput, it was suitable for isolation of aesculin from Cortex fraxinus, and also has good potential on the separation and purification of effective compounds from natural product.
    Journal of Separation Science 12/2012; 35(24):3609-14. DOI:10.1002/jssc.201200790 · 2.59 Impact Factor
  • Xiaohua Xiao · Xiaoxi Si · Xing Tong · Gongke Li
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    ABSTRACT: Nigakinones are the main effective compounds of Picrasma quassioides (D. Don) Benn and are widely used in traditional Chinese medicine, therefore a rapid and efficient separation and purification method is necessary. To develop a new method based on ultrasonic microwave-assisted extraction (UMAE) and high-speed counter-current chromatography (HSCCC) for the rapid separation and purification of nigakinone and methylnigakinone from P. quassioides (D.Don) Benn. Response surface methodology (RSM) was used to optimise the extraction conditions of UMAE: 10.0 g of original sample was extracted with 210 mL of 90% (v/v) aqueous methanol at 60°C for 13 min, ultrasonic power was 100 W and microwave power was dynamically adjusted to the given temperature. After extraction, the extract was introduced into the HSCCC and separated with a hexane:ethyl acetate:methanol:2% acetic acid (9:11:9:11, v/v/v/v) solvent system. About 2.1 mg nigakinone with purity of 96.8% was obtained in one step within 200 min, methylnigakinone was also obtained with a purity of 75.6%. Their chemical structures were identified with ESI-MS and ¹H-NMR. UMAE coupled with HSCCC was found to be a promising and feasible alternative method to separate and purify alkaloids from natural herbs such as P. quassiodes.
    Phytochemical Analysis 09/2012; 23(5):540-6. DOI:10.1002/pca.2352 · 2.45 Impact Factor
  • Xiaohua Xiao · Xiaoxi Si · Zhiquan Yuan · Xianfang Xu · Gongke Li
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    ABSTRACT: A rapid and efficient method for the separation and purification of fucoxanthin from edible brown algae by microwave-assisted extraction coupled with high-speed countercurrent chromatography was developed. The algae were first extracted using microwave-assisted extraction, then the dried extract was dissolved and directly introduced into the high-speed countercurrent chromatography system with a two-phase solvent system consisting of hexane-ethyl acetate-ethanol-water (5:5:6:4, v/v/v/v). The isolation was done in less than 75 min, and a total of 0.83 mg, 1.09 mg, and 0.20 mg fucoxanthin were obtained from 25.0 g fresh Laminaria japonica Aresch, 1.5 g dry Undaria pinnatifida (Harv) Sur, and 15.0 g dry Sargassum fusiforme (Harv) Setch, respectively. The purity of fucoxanthin determined by HPLC was over 90% and its structure was further identified by LC-ESI-MS and (1) H-NMR.
    Journal of Separation Science 09/2012; 35(17):2313-7. DOI:10.1002/jssc.201200231 · 2.59 Impact Factor
  • Ting Zhou · Xiaohua Xiao · Gongke Li
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    ABSTRACT: Microwave accelerated selective Soxhlet extraction (MA-SSE), a novel selective extraction technique, was investigated in this study. A Soxhlet extraction system containing a glass filter was designed as an extractor. During the procedure of MA-SSE, both the target analytes and the interfering components were extracted from the sample into the extraction solvent enhanced by microwave irradiation. After the solvent flowed though the sorbent, the interfering components were adsorbed by the sorbent, and the target analytes remaining in the solvent were collected in the extraction bottle. No cleanup or filtration was required after extraction. The efficiency of the MA-SSE approach was demonstrated in the determination of organophosphorus and carbamate pesticide residues in ginseng by gas chromatography/mass spectrometry (GC/MS). Under the optimized conditions, low limits of detection (0.050-0.50 μg/kg) were obtained. The recoveries were in the range of 72.0-110.1% with relative standard deviations less than 7.1%. Because of the effect of microwave irradiation, MA-SSE showed significant advantage compared with other extraction techniques. The sorbent used in this study showed good cleanup ability. The mechanism of MA-SSE was demonstrated to be based on the rupture of the cell walls according to the structural changes of ginseng samples. On the basis of the results, MA-SSE as a simple and effective sample preparation technique for the analysis of pesticide residues in complex matrixes shows great promise.
    Analytical Chemistry 06/2012; 84(13):5816-22. DOI:10.1021/ac301274r · 5.83 Impact Factor
  • Heyuan Qiu · Xiaohua Xiao · Gongke Li
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    ABSTRACT: A method of microwave-assisted extraction coupled with high-speed counter-current chromatography was established for separation and purification of isopimpinellin, pimpinellin and phellopterin from Toddalia asiatica (L.) Lam. The conditions of MAE including the extraction solvent, size of sample, solid/liquid ratio, extraction temperature and extraction time were optimized by a mono-factor test. That is, 2.0 g dried powder of T. asiatica (L.) Lam of 0.30-0.15 mm size was extracted with 20 mL (solid/liquid ratio of 1:10, g/mL) methanol under 50 °C for 1 min. The crude extract was separated and purified by high-speed counter-current chromatography with hexane-ethyl acetate-methanol-water (5:5:5.5:4.5, v/v/v/v) solvent system. 0.85 mg/g of isopimpinellin, 2.55 mg/g of pimpinellin and 0.95 mg/g of phellopterin were obtained from original sample in one-step within 240 min, the purity determined by high performance liquid chromatography was 95.0%, 99.1% and 96.4%, respectively. Their chemical structures were further identified by mass spectroscopy and nuclear magnetic resonance spectroscopy. The results demonstrated that microwave-assisted extraction coupled with high-speed counter-current chromatography was a feasible, economical and efficient technique for rapid extraction, separation and purification of effective compounds from natural products.
    Journal of Separation Science 04/2012; 35(7):901-6. DOI:10.1002/jssc.201100995 · 2.59 Impact Factor
  • Xiaohua Xiao · Wei Song · Jiayue Wang · Gongke Li
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    ABSTRACT: In this study, low temperature vacuum microwave-assisted extraction, which simultaneous performed microwave-assisted extraction (MAE) in low temperature and in vacuo environment, was proposed. The influencing parameters including solid/liquid ratio, extraction temperature, extraction time, degree of vacuum and microwave power were discussed. The predominance of low temperature vacuum microwave-assisted extraction was investigated by comparing the extraction yields of vitamin C, β-carotene, aloin A and astaxanthin in different foods with that in MAE and solvent extraction, and 5.2-243% increments were obtained. On the other hand, the chemical kinetics of vitamin C and aloin A, which composed two different steps including the extraction step of analyte transferred from matrix into solvent and the decomposition step of analyte degraded in the extraction solvent, were proposed. All of the decomposition rates (K(2)) for the selected analyte in low temperature, in vacuo and in nitrogen atmosphere decreased significantly comparing with that in conventional MAE, which are in agreement with that obtained from experiments. Consequently, the present method was successfully applied to extract labile compound from different food samples. These results showed that low temperature and/or in vacuo environment in microwave-assisted extraction system was especially important to prevent the degradation of labile components and have good potential on the extraction of labile compound in foods, pharmaceutical and natural products.
    Analytica chimica acta 01/2012; 712:85-93. DOI:10.1016/j.aca.2011.11.034 · 4.52 Impact Factor
  • Ting Zhou · Xiaohua Xiao · Gongke Li
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    ABSTRACT: A novel one-step sample preparation technique termed hybrid field-assisted solid-liquid-solid dispersive extraction (HF-SLSDE) was developed in this study. A simple glass system equipped with a condenser was designed as an extraction vessel. The HF-SLSDE technique was a three-phase dispersive extraction approach. Target analytes were extracted from the sample into the extraction solvent enhanced by the hybrid field. Meanwhile, the interfering components were adsorbed by dispersing sorbent. No cleanup step preceded chromatographic analysis. The efficiency of the HF-SLSDE approach was demonstrated in the determination of organochlorine pesticide (OCP) residues in tobacco with a gas chromatography-electron capture detector (GC-ECD). Various operation conditions were studied systematically. Low detection limits (0.3-1.6 μg/kg) and low quantification limits (1.0-4.5 μg/kg) were achieved under the optimized conditions. The recoveries of OCPs ranged from 70.2% to 118.2%, with relative standard deviations of <9.6%, except for the lowest fortification level. Because of the effect of the hybrid field, HF-SLSDE showed significant predominance compared with other extraction techniques. The dispersing sorbent with good cleanup ability used in this study was also found to be a microwave absorption medium, which could heat the nonpolar extraction solvent under microwave irradiation. Different microstructures of tobacco samples before and after extractions demonstrated the mechanism of HF-SLSDE was based on an explosion at the cell level. According to the results, HF-SLSDE was proved to be a simple and effective sample preparation method for the analysis of pesticide residues in solid samples and could potentially be extended to other nonpolar target analytes in a complex matrix.
    Analytical Chemistry 11/2011; 84(1):420-7. DOI:10.1021/ac202798w · 5.83 Impact Factor
  • Xiaohua Xiao · Xiaoxi Si · Xing Tong · Gongke Li
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    ABSTRACT: In the present work, five flavonoids and diarylheptanoid, namely, alpinetin, pinocembrin chalcone, pinocembrin, cardamomin and 1,7-diphenyl-4,6-heptadien-3-one, were simply and rapidly prepared from Alpinia katsumadai hayata (A. katsumadai) by microwave-assisted extraction (MAE) followed with high-speed counter-current chromatography (HSCCC). The critical conditions of MAE and HSCCC were optimized. 2.0g crude sample was extracted with MAE, and then directly separated and purified by HSCCC with a two-phase solvent system composed of hexane–ethyl acetate–methanol–water (3:7:6:4, v/v/v/v), and 7.5mg of alpinetin, 1.9mg of pinocembrin chalcone, 2.6mg of 1,7-diphenyl-4,6-heptadien-3-one with purities of 98.3%, 96.9% and 93.0% were obtained respectively in a single step within 4h. 4.0mg mixture of cardamomin and pinocembrin from HSCCC was further separated by prep-HPLC, 2.1mg of 99.4% pinocembrin and 1.4mg of 99.8% cardamomin were obtained respectively. The purities of compounds were determined by HPLC and their chemical structures were further identified by ESI-MS and 1H NMR. The results demonstrated that MAE coupled with HSCCC was a feasible, economical and efficient technique for rapid extraction, separation and purification of effective compounds in natural products.
    Separation and Purification Technology 10/2011; 81(3):265-269. DOI:10.1016/j.seppur.2011.07.013 · 3.07 Impact Factor
  • Xing Tong · Xiaohua Xiao · Gongke Li
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    ABSTRACT: An on-line method based upon dynamic microwave-assisted extraction (DMAE) coupled with high-speed counter-current chromatography (HSCCC) was developed for continuous isolation of nevadensin from Lyeicnotus pauciflorus Maxim. The DMAE parameters were optimized by means of the Box-Behnken design. The maximum extraction yield was achieved using 30:1 ml/g of liquid-solid ratio, 10 ml/min of solvent flow rate and 200 W of microwave power. The crude extracts were then separated by HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (7:3:5:5, v/v/v/v). 13.0mg of nevadensin was isolated from 15.0 g original sample by HSCCC with five times sample injection in 12h, and the isolation yield of nevadensin was 0.87 mg/g. The average purity of nevadensin was higher than 98.0%. The chemical structure of collected fraction was identified by HPLC, ESI-MS and (1)H NMR. The results indicated that this on-line method was effective and fast for high-throughput isolation of nevadensin from L. pauciflorus Maxim.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 08/2011; 879(24):2397-402. DOI:10.1016/j.jchromb.2011.06.035 · 2.69 Impact Factor
  • Si Zhou · Xiaohua Xiao · Gongke Li
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    ABSTRACT: In recent years, food safety incidents are increasing due to the environmental pollution, abuse of additives, improper storage and so on. Rapid detection techniques are fast, simple and efficient for the requirements of preliminary screening to food security. In this paper, the rapid detection methods for food safety, including enzyme inhibition, biosensors and immunoassay, are reviewed, and the prospects of the future developments are expected.
    Se pu = Chinese journal of chromatography / Zhongguo hua xue hui 07/2011; 29(7):580-6.
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    Ting Zhou · Xiaohua Xiao · Gongke Li · Zong-wei Cai
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    ABSTRACT: In this paper, the application of polyethylene glycol (PEG) aqueous solution as a green solvent in microwave-assisted extraction (MAE) was firstly developed for the extraction of flavone and coumarin compounds from medicinal plants. The PEG solutions were optimized by a mono-factor test, and the other conditions of MAE including the size of sample, liquid/solid ratio, extraction temperature and extraction time were optimized by means of an orthogonal design L(9) (3(4)). Subsequently, PEG-MAE, organic solvent-MAE, and conventional heating reflux extraction (HRE) were evaluated with nevadensin extraction from Lysionotus pauciflorus, aesculin and aesculetin extraction from Cortex fraxini. Furthermore, the mechanism of PEG-MAE was investigated, including microwave-absorptive property and viscosity of PEG solutions, the kinetic mechanism of PEG-MAE and different microstructures of those samples before and after extraction. Under optimized conditions, the extraction yields of nevadensin from L. pauciflorus, aesculin and aesculetin from C. fraxini were 98.7%, 97.7% and 95.9% in a one-step extraction, respectively. The recoveries of nevadensin, aesculin and aesculetin were in the range of 92.0-103% with relative standard derivation lower than 3.6% by the proposed procedure. Compared with organic solvent-MAE and conventional extraction procedures, the proposed methods were effective and alternative for the extraction of flavone and coumarin compounds from medicinal plants. On the basis of the results, PEG solution as a green solvent in the MAE of active compounds from medicinal plants showed a great promising prospect.
    Journal of Chromatography A 06/2011; 1218(23):3608-15. DOI:10.1016/j.chroma.2011.04.031 · 4.26 Impact Factor
  • Jianchao Deng · Xiaohua Xiao · Xing Tong · Gongke Li
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    ABSTRACT: In this paper, a simple method for the rapid extraction, separation and purification of bergenin from Ardisia crenata sims and Rodgersia sambucifolia hemsl by microwave-assisted extraction (MAE) coupled with high-speed counter-current chromatography (HSCCC) was developed. The MAE conditions were optimized and 2.0 g sample was extracted using 60% (v/v) aqueous methanol as extraction solvent with liquid/solid ratio of 10/1 (mL/g) at 60 °C for 15 min. The crude extract of MAE was separated and purified directly by HSCCC using ethyl acetate–n-butanol–water (3:2:5, v/v/v) solvent system. In less than 3.5 h, 18.6 or 25.0 mg of bergenin was obtained from 160 mg crude extract of A. creanta or R. sambucifolia in one-step separation, respectively. The purity of bergenin was over 99% determined by HPLC and its chemical structure was further identified by ESI-MS, 1H NMR and UV. The results indicate that microwave-assisted extraction coupled with high-speed counter-current chromatography is very suitable for the extraction, separation and purification of bergenin from A. creanta and R. sambucifolia.
    Separation and Purification Technology 08/2010; 74(2-74):155-159. DOI:10.1016/j.seppur.2010.05.018 · 3.07 Impact Factor
  • Xiaohua Xiao · Yi Yin · Yuling Hu · Gongke Li
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    ABSTRACT: A sensitive and accurate method consisting of microwave-assisted extraction (MAE) coupled with single drop microextraction (SDME) and HPLC was developed for the determination of four trace estrogen adulterants, including estriol (E3), estradiol (E2), ethinyl estradiol (EE), and estrone (E1), in different soybean dietary supplements. The samples were extracted by MAE; the extracts were cleaned up and enriched by SDME, and then analyzed by HPLC. The conditions of MAE were optimized, and the effects of solvent and extraction time in SDME on the enrichment capacity were studied. The enrichment factors of E3, E2, EE, and E1 under the optimized conditions were 247-, 335-, 316-, and 319-fold, respectively. The linear range of the MAE-SDME-HPLC method ranged from 5.0 to 180.0 microg/L, and the detection limit from 1.1 to 1.2 microg/L. The RSD ranged from 7.9 to 9.6%. Three soybean dietary supplements, including oral liquid, capsule, and tablet forms, were analyzed. The spike recovery was more than 70%, with RSD lower than 13.2%. It was shown that the proposed method was accurate, sensitive, and suitable for the determination of trace analytes in complex samples.
    Journal of AOAC International 01/2010; 93(3):849-54. · 1.39 Impact Factor
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    Xiaohua Xiao · Zongning Guo · Jianchao Deng · Gongke Li
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    ABSTRACT: In this paper, a simple method based upon microwave-assisted extraction (MAE) coupled with high-speed counter-current chromatography (HSCCC) for the rapid isolation, separation and purification of isofraxidin from Sarcandra glabra (thunb.) was developed. The dry extract obtained from MAE was directly introduced into the HSCCC for separation and purification. The critical experimental parameters of MAE and HSCCC were optimized. 2 g of Sarcandra glabra sample was extracted with 20 mL 60% (v/v) ethanol aqueous at 65 °C for 20 min at 500 W of microwave irradiation, then the extracting solution was concentrated to 300 mg dry extract. The dry extract was dissolved with the lower phase of n-hexane–ethyl acetate–methanol–water (1:2:1:2, v/v/v/v), separated and purified by preparative HSCCC. 300 mg dry extract can be introduced into the HSCCC system in one-step and 1.20 mg of isofraxidin was obtained with purity over 99% in 2.5 h. The purity of isofraxidin was determined with HPLC and its chemical structure was identified with 1H NMR. The results indicate that the method is simple, fast and efficient. The method has good potential on the separation and purification of effective compounds from natural product.
    Separation and Purification Technology 08/2009; 68(2-68):250-254. DOI:10.1016/j.seppur.2009.05.011 · 3.07 Impact Factor