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Chinese Journal of Chromatography
2007, Vol. 25, No. 3
Online: 30 May 2007

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Applications of Ionic Liquids in Chromatography QIU Hongdeng, HU Yunyan, LIU Xia , JIANG Shengxiang 2007, 25 (3):  293-297.  Abstract ( 2379 )   [Full Text(HTML)] () PDF (182KB) ( 1206 )   Ionic liquids are solvents that may have great potentials in chemical analysis. A large variety of analytical applications of ionic liquids have emerged recently. In this paper, the applications of ionic liquids in chromatography including capillary electrophoresis, gas chromatography and liquid chromatography are reviewed.

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Advances in Ion Exchange Monolithic Columns HUANG Xiaojia, HUANG Benli 2007, 25 (3):  298-302.  Abstract ( 2148 )   [Full Text(HTML)] () PDF (148KB) ( 895 )   Recent advances and trends in the development of ion exchange monolithic columns are reviewed. Special attention is paid to the preparation methods and their applications in the environment and biology. The problems of ion exchange monolithic columns and its future are discussed. Fifty references are cited.

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Development of Metal Ions Analysis by Ion Chromatography YU Hong, WANG Yuxin 2007, 25 (3):  303-309.  Abstract ( 2540 )   [Full Text(HTML)] () PDF (193KB) ( 1055 )   Analysis of metal ions by ion chromatography, including cation-exchange ion chromatography, anion-exchange ion chromatography and chelation ion chromatography, is reviewed. The cation-exchange ion chromatography is a main method for the determination of metal ions. Stationary phases in cation-exchange ion chromatography are strong acid cation exchanger (sulfonic) and weak acid cation exchanger (carboxylic). Alkali metal ions, alkaline earth metal ions, transition metal ions, rare earth metal ions, ammonium ions and amines can be analyzed by cation-exchange ion chromatography with a suitable detector. The anion-exchange ion chromatography is suitable for the separation and analysis of alkaline earth metal ions, transition metal ions and rare earth metal ions. The selectivity for analysis of metal ions with anion-exchange ion chromatography is good. Simultaneous determination of metal ions and inorganic anions can be achieved using anion-exchange ion chromatography. Chelation ion chromatography is suitable for the determination of trace metal ions in complex matrices. A total of 125 references are cited.

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Development of Microwave Plasma Atomic Emission Detectors for Gas Chromatography YUAN Mao, SHI Yuhua, YU Aimin, ZHANG Hanqi, JIN Qinhan 2007, 25 (3):  310-315.  Abstract ( 2140 )   [Full Text(HTML)] () PDF (167KB) ( 744 )   Three microwave plasmas including microwave induced plasma, capacitively coupled microwave plasma and microwave plasma torch as atomic emission detectors for gas chromatography are evaluated in their history, application and restriction, separately. The development of microwave plasma atomic emission detectors for gas chromatography is prospected.

Communications

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Separation and Determination of Madecassic Acid in Triterpenic Genins of Centella asiatica by High Performance Liquid Chromatography Using β-Cyclodextrin as Mobile Phase Additive PAN Jian, KAI Guiqing, YUAN Chuanxun, ZHOU Beibei, JIN Risheng, YUAN Yuan 2007, 25 (3):  316-318.  Abstract ( 2825 )   [Full Text(HTML)] () PDF (1127KB) ( 811 )   Centella asiatica (L.) Urban is a tropical medicinal plant with a long history of therapeutic uses. Madecassic acid and terminolic acid, which are a pair of structural isomers, are two constituents of Centella asiatica. A method using reversed-phase high performance liquid chromatography in which β-cyclodextrin (β-CD) was the additive in mobile phase has been developed for separation of the structural isomers and determination of madecassic acid. The two compounds can be isolated with high resolution on a C18 reversed-phase column with the addition of β-CD in the mobile phase. The separation mechanism of the isomers was discussed. It was assumed that the separation of the isomers might have been resulted from different inclusion forces of complexes with β-CD. The effects of β-CD concentration and the pH of mobile phase on resolution were investigated. It was found that the resolution of the isomers increased with the increase of β-CD concentration when the mobile phase consisted of methanol-water (65∶35, v/v) at pH 4. The correlation coefficient (r2) of the linear calibration curve between peak area and concentration of madecassic acid was 0.9989 in the range of 0.1-5.0 g/L. This method was successfully used to determine the madecassic acid in triterpenic genins of Centella asiatica.

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Comparison of Micellar Electrokinetic Chromatography and Microcolumn High Performance Liquid Chromatography for Resveratrol Analysis FAN Enguo, HUANG Xiaojing, ZHANG Kai, BAI Yuhua, GAO Ruyu, YAN Chao 2007, 25 (3):  319-321.  Abstract ( 2573 )   [Full Text(HTML)] () PDF (200KB) ( 709 )   Resveratrol, occurring in trans- and cis-isomeric forms, is a phytoalexin with pharmacological activities, for example, anti-cancer, anti-cardiovascular disease, and life-span increasing properties. Two analytical methods, namely, micellar electrokinetic chromatography (MEKC) and microcolumn high performance liquid chromatography (μ-HPLC), were developed and compared for resveratrol isomer separation. Both methods are suitable for resveratrol analysis owing to their performances of high speed, good reproducibility， and low consumption of solvents and samples.

Articles

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Effect of Sargassum fusiforme Polysaccharides on the Complex Mobility of Erythrocytes in Tumor-Bearing Organisms Using High Performance Capillary Electrophoresis JI Yubin, WANG Chong, WU Tao, JI Chenfeng, 2007, 25 (3):  322-325.  Abstract ( 2412 )   [Full Text(HTML)] () PDF (306KB) ( 753 )   This study analyzed the effect of Sargassum fusiforme polysaccharides (SFPS) on the complex mobility of erythrocytes in tumor-bearing organisms. A mouse tumor model was developed in which mice were intraperitoneally injected with high, medium, and low dosages of SFPS for 7 d. The erythrocytes were collected and prepared into suspensions, and the complex mobilities of cells were measured using high performance capillary electrophoresis (HPCE). Experimental conditions included the following: capillaries, 75 μm×50 cm; buffer for electrophoresis, phosphate solution containing hydroxypropylmethyl cellulose (0.1 mol/L, pH 7.4); injection pressure, 3.448 kPa; injection time, 10 s; separation voltage, 20 kV; column temperature, 25 ℃. The electroosmotic mobility was calculated to be 2.16×10-4 cm2·V-1·s-1. It was found that SFPS can decrease the migration time of erythrocytes in tumor-bearing organisms, which was 17.56 min for the control group, 13.96 min for the low dosage group, 12.90 min for the medium dosage group, 13.51 min for the high dosage group, and 11.51 min for the normal group, and increase its complex mobility, which was 1.06×10-4 cm2·V-1·s-1 for the control group, 1.19×10-4 cm2·V-1·s-1 for the low dosage group, 1.29×10-4 cm2·V-1·s-1 for the medium dosage group, 1.23×10-4 cm2·V-1·s-1 for the high dosage group, and 1.45×10-4 cm2·V-1·s-1 for the normal group. Compared with the negative control group, all three dosage groups had significant differences (P＜0.01) in the complex mobility of erythrocytes. It was found that SFPS can change the complex mobility of erythrocytes in tumor-bearing organisms with the tendency to the condition in normal organisms, which is possibly because SFPS can change the charges density on erythrocytes surface. It is believed that HPCE can be used as an auxiliary tool for determining the physiological state and functions of erythrocytes.

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On-Line Sample Stacking for Determination of Carnosine-Related Peptides by Capillary Electrophoresis HUANG Ying, DUAN Jianping, ZHANG Jianhua, CHEN Guonan 2007, 25 (3):  326-331.  Abstract ( 2126 )   [Full Text(HTML)] () PDF (470KB) ( 670 )   Two on-line sample stacking methods in capillary electrophoresis, large volume sample stacking using reversed pressure as a pump (LVSRP) and large volume sample stacking using electroosmotic flow (EOF) pump (LVSEP)， were developed for the separation and determination of carnosine, anserine and homocarnosine. The principles of the two stacking methods are described. Various parameters affecting capillary electrophoresis separation and sample stacking were studied and optimized. The optimal stacking conditions for LVSRP were as follows: hydrodynamic sample injection at 41.4 kPa (60 s), then injection of a short plug of buffer at 13.8 kPa×15 s, stacking of sample at a voltage of 10 kV with a back pressure of 34.5 kPa, and separation in phosphate buffer (pH 5.63, 100 mmol/L) at a voltage of 15 kV. The optimal stacking conditions for LVSEP were as follows: hydrodynamic sample injection at 48.3 kPa (60 s), stacking at a voltage of 20 kV and separation at a voltage of -20 kV in a buffer of 100 mmol/L phosphate-0.5 mmol/L cetyltrimethylammonium bromide (CTAB) (pH 5.31). About 40-60 fold improvement of sensitivity was achieved without loss of separation efficiency by LVSRP and LVSEP, when compared with the normal CZE method. Under the optimum conditions, excellent linear responses were obtained in the concentration range of 0.080-5.0 μmol/L. The relative standard deviations (RSDs) of peak height were 2.4%-2.7% and 0.6%-4.0% for LVSRP and LVSEP, respectively. The concentration limits of detection (defined as signal-to-noise ratio of 3) of carnosine, anserine and homocarnosine obtained for LVSRP and LVSEP were 41-58 nmol/L and 35-43 nmol/L, respectively.

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Single-Step Purification of Galectin in Earthworm Using Sepharose CL-6B Affinity Chromatography CHEN Yihong, HUANG Huimin, LI Renqiang 2007, 25 (3):  332-336.  Abstract ( 2531 )   [Full Text(HTML)] () PDF (1371KB) ( 758 )   The S-type lectins in annelida are different in molecular structure and biochemical properties from that of common galectin and are valuable in anticancer study. Based on their specificity, Sepharose CL-6B affinity chromatography was adopted in this study to separate the S-type lectin in annelida from earthworms, in which EDTA-MEPBS (2 mmol/L EDTA, 4 mmol/L β-mercaptoethanol, 150 mmol/L NaCl, 20 mmol/L phosphate, pH 7.2) was used as an equilibrium solution and aqueous ammonia solution (150 mmol/L, pH 10.5) as an eluent. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that the relative molecular mass of the obtained protein in this purification procedure was about 32000 and it could be further separated into fractions with relative molecular mass about 15000. Hemagglutination experiment and fluorescence analysis demonstrated that this protein possessed the characteristics of agglutinin and its complex with lactose. This indicated that the target protein was one of the S-type lectins in annelida. This study may offer a novel and rapid method for purifying the S-type lectins in annelida in large scale.

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A Functional Fingerprint of Traditional Chinese Medicine for Measuring the Oil-Water Partition Coefficients YAN Lei, GONG Ping, YUAN Lin, JIANG Xuemei, XIA Zhining, 2007, 25 (3):  337-340.  Abstract ( 2292 )   [Full Text(HTML)] () PDF (217KB) ( 839 )   Following the principle and method on the measurement of oil-water partition coefficients by microemulsion electrokinetic chromatography (MEEKC), a traditional Chinese medicine fingerprint (TCM-FP) was established. The components which were extracted from the TCM were separated from each other by MEEKC under optimized operation conditions. The conditions of running solution were of 70 mmol/L SDS, 87 mmol/L n-heptane, 814 mmol/L n-butanol and 5 mmol/L sodium tetraborate with pH value of 8.80. The uncoated fused silica capillary used was 54 cm×75 μm with an effective length of 45 cm. The UV detection was carried out at 210 nm and an electrophoretic voltage of 15 kV was applied. SPSS program was used for the nonlinear regression of migration time and log Pow values of the standard compounds from literature, and the reliability of the established method has been investigated. As a result, the standard equation of regression with good linearity (r=0.9880) was obtained. The log Pow values of compounds measured under the same operation conditions were well consistent with those from literature. This method was applied to L. lucidum in which oleanolic acid is a main effective component. Besides the establishment of its TCM-FP, the log Pow of oleanolic acid, 3.63, was also obtained. The functional fingerprint of traditional Chinese medicine can give the log Pow of the extracts from TCM, reflect oil-water partition character of the constituents, and is of great significance to the selection of solvents, the design of dosage form, and the improvement of production technology.

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Determination of Benzoyl Peroxide in Wheat Flour by Micellar Capillary Electrophoresis On-Line Sweeping Concentration Technique WANG Quan, YANG Gengliang, ZHANG Li 2007, 25 (3):  341-343.  Abstract ( 1877 )   [Full Text(HTML)] () PDF (220KB) ( 682 )   A method for the determination of benzoyl peroxide in wheat flour was established by a micellar capillary electrophoresis on-line sweeping concentration technique. Benzoyl peroxide was ultrasonically extracted with methanol, filtrated by nylon membrane (0.45 μm), and analyzed directly by capillary electrophoresis. The conditions of pH of background solution, the concentration of sodium dodecyl sulfate (SDS) and injection time were investigated. The results demonstrated that the optimum separation efficiency can be obtained by using a running buffer of 0.02 mol/L borax-boric acid containing 0.04 mol/L SDS (pH 9.0), UV detection at a wavelength of 214 nm and an applied voltage of 10 kV. These conditions allowed up to 150-fold concentration of benzoyl peroxide and a linear correlation of benzoyl peroxide was obtained in a range from 0.002 g/L to 0.012 g/L. The detection limit was 2 mg/L. The results also showed that the method is precise, simple, and cost-effective.

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Two-Step Chromatographic Method for the Separation and Purification of Recombinant Angiogenesis Inhibitor Kringle 5 JIA Xingui, BIAN Liujiao 2007, 25 (3):  344-347.  Abstract ( 2167 )   [Full Text(HTML)] () PDF (1981KB) ( 660 )   The Kringle 5 domain of plasminogen, which was previously shown to inhibit angiogenesis in vitro and in vivo, is one of the most potent angiogenesis inhibitors known to date. A two-step chromatographic method, which consists of Chelating Sepharose Fast Flow chelated with Ni2+ affinity medium and Sephadex G-75 medium, was established to separate and purify recombinant angiogenesis inhibitor Kringle 5 (rK5). Through the two-step chromatographic purification process, the obtained rK5 was confirmed to be homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and its relative molecular mass was estimated to be about 32000, which matched well with the prediction by gene sequence. Its purity was about 98%, and the total protein recovery of this method was 0.63%. In addition, it was found that it inhibited the blood vessel growth of chick embryo chorioallantoic membrane effectively.

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Investigation on Binding Interaction of Berberine Chloride with Bovine Serum Albumin Immobilized onto Chromatographic Supports by Frontal Chromatography ZENG Xiaolei, LEI Genhu, WEI Yinmao 2007, 25 (3):  348-352.  Abstract ( 2247 )   [Full Text(HTML)] () PDF (356KB) ( 699 )   Berberine chloride (BC) is a major active constituent of coptis and can be used as an antipyrotic and antibacterial medicine. Frontal analysis was used to investigate the changes in the binding constant (K), retention factor (k), binding ratio (PPB) and mole of binding sites (mL) for the binding of BC on an immobilized bovine serum albumin (BSA) column at several temperatures and to obtain the thermodynamic parameters in the binding process. At 30 ℃, the binding constant was 4.79×104 L/mol. K, k and mL all decreased as the temperature was increased. Among these three parameters, the change magnitude in mL was the most significant. It could be concluded that the decrease in the retention of BC was caused by the decrease of both K and mL, and the change in the configuration of BSA was considered to be the main reason for the decrease of binding site. The thermodynamic analysis indicated that the main driving force for the interaction between BC and BSA is electrostatic force.

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Behaviors of β-Glucan from Grifola frondosa in High Performance Gel Permeation Chromatography SONG Letian, YU Guangli, ZHAO Xia, GAO Haodong, YANG Xiaohua, YANG Hai 2007, 25 (3):  353-355.  Abstract ( 2111 )   [Full Text(HTML)] () PDF (286KB) ( 745 )   The high performance gel permeation chromatographic (HPGPC) behaviors of four β-1,3/1,6-glucans (GF1, GF2, GF3, GF4) with different protein contents and one α-1,4/1,6-glucan (P100) from Grifola frondosa were examined with different concentrations of NaCl solution and pH values. The experimental results showed that the relative molecular mass (Mr) of the β-glucans sharply dropped as the NaCl concentration was less than 0.025 mol/L and then tended to be stable as the NaCl concentration was raised from 0.1 to 0.2 mol/L， the Mr increased quickly from pH 3 to 6, and then maintained stable from pH 6 to 9, but slightly increased as the pH value was higher than 9. However, the Mr of the α-1,4/1,6-glucan was slightly affected by either different concentrations of NaCl or different pH values. The β-glucan existed in a super-helix structure in aqueous solution, which could be influenced by the NaCl concentration and pH value. These factors led to the different molecular aggregation states, and the increase or decrease of the Mr of β-glucans, displaying a variety of HPGPC behaviors.

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Determination of Trace Polycyclic Aromatic Hydrocarbons in Surface Sediments of Huangpu River by High Performance Liquid Chromatography LIU Ying, CHEN Ling, TANG Yinjian, HUANG Qinghui, ZHAO Jianfu 2007, 25 (3):  356-361.  Abstract ( 2229 )   [Full Text(HTML)] () PDF (2938KB) ( 785 )   The 16 polycyclic aromatic hydrocarbons, included in US EPA Priority Pollutant List, in surface sediments from Huangpu River were qualified and quantified using high performance liquid chromatograph (HPLC) coupled with photodiode array detector (PDA). On the basis of qualification by retention times, the ultraviolet spectra of 16 PAHs obtained from PDA were used to improve the qualification. Furthermore, benzo［b］fluoranthene, benzo［k］fluoranthene, benzo［a］pyrene and benzo［e］pyrene in sediment samples were identified with the differences of ultraviolet spectra of isomers. The quantitative method for 16 trace PAHs in the sediments was developed. In order to intensify ultraviolet response of target components and reduce those of the interferents, detection wavelengths of 16 PAHs were optimized. The limits of detection were improved further and were from 1.1 to 18.3 ng/g on dry basis, and spiked recoveries from environmental samples were 87%-113%. Therefore, the quantitative method in this study was sensitive and accurate and was satisfied for the determination of trace PAHs in environmental samples. Finally, the quantitative method was successfully used for the analysis of the surface sediments of Huangpu River. All the PAHs, except acenaphthylene, were detected. The concentrations of the PAHs were 10.1-253.0 ng/g and their relative standard deviations (RSD) were less than 10%.

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Determination of Carbamate Pesticides in Reservoir Water by Hollow Fiber-Based Liquid Phase Microextraction Coupled with High Performance Liquid Chromatography YANG Xiumin, WANG Zhi, WANG Chun, HAN Dandan, CHEN Yongyan, SONG Shuangju 2007, 25 (3):  362-366.  Abstract ( 2117 )   [Full Text(HTML)] () PDF (1593KB) ( 831 )   An analytical method for the determination of carbamate pesticides (carbofuran, carbaryl, isoprocarb and diethofencarb) in reservoir water using hollow fiber-based liquid phase microextraction (HF-LPME) coupled with high performance liquid chromatography (HPLC) was developed. Some main experimental parameters that affect the extraction efficiency were optimized. Toluene was selected as both the extraction solvent and the impregnation solvent. The extraction was carried out at room temperature (20 ℃) in a 5 mL Teflon-lined septum cap vial filled with 4.5 mL of sample solution at a stirring rate of 720 r/min for 20 min. The extract was dried under nitrogen stream at room temperature. The dried residue was then dissolved in the mobile phase for HPLC analysis. The separation was carried out on a Baseline C18 column (4.6 mm×250 mm, 5.0 μm) with methanol-water (60∶40, v/v) as the mobile phase at a flow rate of 1.0 mL/min. The detection for carbofuran, carbaryl, isoprocarb and diethofencarb was selected at 200, 223, 200 and 208 nm, respectively. The average enrichment factors for the four analytes were greater than 45. The linear range for the quantification of the four analytes was 10-100 μg/L （r＞0.99）. The limits of detection (LODs) were 5, 1, 5 and 3 μg/L (S/N=3) for carbofuran, carbaryl, isoprocarb and diethofencarb, respectively. Good recoveries (82.0%-102.2%) and good reproducibilities (2.0%-6.2%, n=6) were achieved.

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Determination of Flavonoid Glycosides in Pyrola decorate by Reversed-Phase High Performance Liquid Chromatography ZHANG Yuanyuan, CHEN Xiaohui, SUN Yanyan, BI Kaishun 2007, 25 (3):  367-370.  Abstract ( 2099 )   [Full Text(HTML)] () PDF (186KB) ( 803 )   A reversed-phase high performance liquid chromatographic method was developed for the simultaneous determination of five flavonoid glycoside components, namely hyperin, isoquercitrin, 2″-O-galloylhyperin, quercetin 3-O-α-L-arabinofuranoside and quercitrin in Pyrola decorate. After being immersed in 70% (v/v) ethyl alcohol for 6 h, samples were ultrasonically extracted for 30 min. The separation was carried out on a Zorbax Extend-C18 column (250 mm×4.6 mm, 5 μm) using acetonitrile-water (14∶86, v/v) as mobile phase at a flow rate of 1.0 mL/min. The absorbance was monitored at 350 nm and the column temperature was 35 ℃. All analytes showed good linearity within the test ranges and the recoveries were 96.3%-104.2%. Satisfactory precisions were obtained with relative standard deviations less than 5%. The method was simple, accurate and reproducible in the application to the determination of 20 commercial samples of Pyrola decorata collected from different regions of China. It can be used for the quality control of both plant materials and preparations of Pyrola decorate.

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Simultaneous Determination of Wedelolactone and Isodemethyl-wedelolactone in Herba Ecliptae by Reversed-Phase High Performance Liquid Chromatography YUAN Hongxia, ZHAO Yunli, WANG Xiaoying, TANG Qian, GAO Xiaoxia, YU Zhiguo 2007, 25 (3):  371-373.  Abstract ( 2144 )   [Full Text(HTML)] () PDF (182KB) ( 805 )   A reversed-phase high performance liquid chromatographic method (RP-HPLC) was developed for the simultaneous determination of wedelolactone and isodemethylwedelolactone in Herba Ecliptae from different sources. The separation was performed on a Kromasil C18 column (250 mm×4.6 mm, 5 μm), with methanol-0.5% acetic acid (55∶45, v/v) as mobile phase at a flow rate of 1.0 mL/min. The detection wavelength was set at 351 nm and the volume of injection was 20 μL. There were good linear relationships between the mass concentrations and the peak areas of isodemethylwedelolactone and wedelolactone in the ranges of 1.6-32.0 mg/L (r=0.9995) and 5.6-112.0 mg/L (r=0.9998), respectively. The recoveries were found to be in the range of 97.5%-98.2% and 99.0%-100.2%, respectively. The results of the experiments have demonstrated that the established method is rapid and simple with good accuracy and reproducibility for the simultaneous determination of wedelolactone and isodemethylwedelolactone. The method is suitable for the quality control of Herba Ecliptae from different sources.

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Preparation, Characterization and Chromatographic Performance of Curcumin Bonded Silica Stationary Phase XU Lili, LI Laisheng, YANG Hanrong 2007, 25 (3):  374-379.  Abstract ( 2408 )   [Full Text(HTML)] () PDF (559KB) ( 832 )   A curcumin bonded silica stationary phase(CCSP)for high performance liquid chromatography was prepared by using γ-glycidoxypropyltrimethoxysilane (KH-560) as coupling reagent. Its structure was characterized by elemental analysis, Fourier transform infrared spectroscopy and thermal analysis. The chromatographic performance and the retention mechanism on the new packing material were evaluated by using neutral, acidic and basic compounds as solute probes and methanol-water as binary mobile phases. A comparative study with ODS was carried out as well. The results showed that CCSP appeared to be excellent reversed-phase stationary phase with versatile chromatographic functions. The curcumin ligand bonded on silica gel can provide n-π and π-π action sites for different analytes because of its integrated conjugated system. Additionally, the polar hydroxyl and carbonyl groups of curcumin facilitated dipole-dipole and hydrogen-bonding interactions between the ligand and solutes in the effective separation process. In comparison with ODS, CCSP has the advantages in fast separation of polar compounds because of its weaker hydrophobicity and various synergistic sites.

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Simultaneous Determination of Nine Organochlorine Pesticide Residues in Textile by High Performance Liquid Chromatography ZHANG Xiang， LIAO Qing， ZHANG Yan 2007, 25 (3):  380-383.  Abstract ( 2407 )   [Full Text(HTML)] () PDF (225KB) ( 868 )   A method for the simultaneous determination of pesticide and herbicide residues in cotton textile by high performance liquid chromatography coupled with diode array detector (HPLC-DAD) has been established. The pesticides and herbicides determined were 2,4-dichlorophenoxy (2,4-D), 2-methyl-4-chlorophenoxy acetic acid (MCPA), dichlorprop, mecoprop, 2,4,5-trichlorophenoxy (2,4,5-T), 2-methyl-4-chlorophenoxy butyric acid (MCPB), β-endosulfan, methoxychlor and 2,2-bis(p-chlorophenyl)-1,1-dichloroethene (DDE). Pesticide and herbicide residues in cotton products were extracted with acetone-petroleum ether by ultrasonic instrument. The extract was analyzed using an SGE C18 column with a linear gradient elution (methanol-phosphoric acid as mobile phase at a flow rate of 0.8 mL/min) and ultraviolet detection at 230 nm. The linear range was 0.5-10 mg/L, and the correlation coefficients were all greater than 0.9988. By using acetone-petroleum ether(4∶1, v/v) as solvent, the recoveries of nine organochlorine pesticides and herbicides at spiked levels of 0.5-2 mg/kg were 85.5%-99.6%. The limits of detection (S/N=3) were 0.05 mg/kg except MCPB, β-endosulfan, methoxychlor and DDE that were 0.10 mg/kg. This method is of high accuracy, easy operation, satisfactory recoveries and good reproducibility. It could be used for the determination of the nine pesticides and herbicides in textile.

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Determination and Distribution of Sulfur Compounds in Coked Gasoline by Gas Chromatography-Sulfur Chemiluminescence Detection YANG Yongtan, WANG Zheng 2007, 25 (3):  384-388.  Abstract ( 2270 )   [Full Text(HTML)] () PDF (228KB) ( 700 )   The method for the separation and determination of sulfur compounds in coked gasoline by gas chromatography-sulfur chemiluminescence detection (GC-SCD) was established. Seventy-four sulfur compounds including hydrogen sulfide, mercaptans, sulfides, disulfides, thiophene, alkyl thiophenes, benzothiophene, alkyl benzothiophenes in a coked gasoline sample were identified by standard samples and past identified results. The retention indexes of different sulfur compounds in coked gasoline under programmed temperature condition were calculated based on the retention times of hydrosulfide, ethyl mercaptan, n-propyl mercaptan, thiophene, 2-methyl thiophene, 2-ethylthiophene, 2-propylthiophene, C4-thiophene (tR=40.28 min), benzothiophene, and methylbenzothiophene (tR=58.13 min). The relative standard deviations of the determination results of main sulfur compounds (isopropyl mercaptan, n-propyl mercaptan, n-butyl mercaptan, 2-methylthiophene, 3-methylthiophene, 2,4-dimethylthiophene, 2,3,4-trimethylthiophene) in coked gasoline were less than 5%, and the detection limit for sulfur was 0.05 mg/L. The linear range of sulfur was 0.2-400 mg/L for each sulfur compounds（r2=0.999）. The contents of sulfur compounds, especially the content of mercaptan, are much more than those in the catalytic gasoline. There is also a big difference in the sulfur contents between 2-methylthiophene and 3-methylthiophene. The data can be useful for the study of hydrodesulfurizing catalyst and industrial process planning.

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Determination of Three Organophosphorous Flame Retardants in Textiles by Gas Chromatography MU Junze, LI Xuan, ZHANG Bin, JIANG Liyuan 2007, 25 (3):  389-391.  Abstract ( 2284 )   [Full Text(HTML)] () PDF (151KB) ( 951 )   A method of simultaneous determination of three organophosphorous flame retardants in textiles by capillary gas chromatograph (GC) combined with nitrogen phosphorus detector (NPD) was developed. The samples were extracted by ultrasonic extraction, filtered by 0.22 μm microporous film and then directly analyzed by GC-NPD. The ultrasonic extraction key factors optimized by the orthogonal design were as follows: the volume ratio of acetone to n-hexane was 2∶8, the extraction time was 40 min and the solvent volume was 35 mL. The linear ranges of tris (2-chloroethyl) phosphate (TCEP), tri-o-cresyl phosphate (TOCP) and tris (2,3-dibromopropyl) phosphate (TRIS) were 0.3758-36.38 μg/mL, 0.3841-38.41 μg/mL and 15.78-1010 μg/mL, respectively, and the detection limits were 0.044 mg/kg, 0.053 mg/kg and 0.82 mg/kg, respectively. Textile samples including cotton, flax, nylon, silk and terylene spiked with different levels of the three flame retardants were employed to investigate the method precision and recovery. For aforementioned analytes, the method precisions were 6.2%, 7.7% and 6.5%, respectively and the method recoveries based on spiked studies were in the range of 83.2%-115.4%. The method is suitable for the determination of three organophosphorous flame retardant residues in textiles in commodity inspection.

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Determination of Endosulfan Pesticide Residues in Litopenaeus vannamai by Capillary Gas Chromatography LIU Xiaosong, HUANG Daxin, LU Shengyu 2007, 25 (3):  392-394.  Abstract ( 2391 )   [Full Text(HTML)] () PDF (206KB) ( 775 )   A method is described for the determination of endosulfan pesticide residues in Litopenaeus vannamai by capillary gas chromatography. The residues of α-endosulfan and β-endosulfan were extracted from the sample with ethyl acetate, and the extract was cleaned up using a neutral alumina column and an active carbon column after concentrated and then eluted with a mixture of n-hexane-ethyl acetate (1∶1, v/v). During the process of purification, the flow rate of eluent was controlled within 3 mL/min. The eluate was collected and evaporated to 1 mL for analysis. The determination was performed on a gas chromatograph equipped with an electron capture detector. The retention time was used for qualification and the external calibration standard was used for quantitation. The results obtained showed that the recoveries were 80.5%-97.3% for α-endosulfan and 81.1%-109.5% for β-endosulfan. The limit of detection (LOD) was 0.002 mg/kg, and the limit of quantitation (LOQ) was 0.007 mg/kg for both. The precision of the method, expressed as the relative standard deviation for the within-laboratory repeatability, was generally below 8.5%. The method was used for the analysis of Litopenaeus vannamai samples from Guangxi Province, a Litopenaeus vannamai aquiculture area in south China.

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Determination of Organic Phosphorus Pesticide Residues in Scallion by Gas Chromatography Coupled with Microwave Clean-Up JIANG Jun, LI An, LI Haiyan, TONG Kexing, ZHOU Lili, ZHOU Huimin, ZHAO Tong 2007, 25 (3):  395-398.  Abstract ( 2211 )   [Full Text(HTML)] () PDF (312KB) ( 842 )   A method for the determination of organic phosphorus pesticide residues is described. It covers 25 residues in scallion including dichlorvos, ethoprophos, phorate, diazinon, disulfoton, dimethoate, pirimiphos-methyl, chlorpyrifos, malathion, fenitrothion, parathion, chlorfenvinphos, ethion, EPN, dyfonate, chlorpyrifos-methyl, parathion-methyl, fenthion, quinalphos, gardona, methidathion, carbophenothion, phosmet, phosalone, and coumaphos. After the scallion samples were heated for 30 s in microwave oven, the residues were extracted with acetonitrile, and then the organic phase was salted out from the matrix. As a result, most of the interfering impurities were abolished in the heating process. In this study, these pesticides were categorized into two groups for analysis. The gas chromatographic analysis was performed on a capillary column (DB-1701, 30 m×0.25 mm×0.25 μm) and determined with a flame photometric detector. Linear correlation coefficients of the 25 organic phosphorus pesticides were not lower than 0.9910 and the linear ranges for most of the compounds were between 0.1 to 5.0 mg/L. The detection limits were between 0.025 and 0.200 mg/L. In recovery study, average recoveries ranged from 85.2% to 119.6% at the fortification levels of 0.05, 0.2 and 0.5 mg/kg and the relative standard deviations were in the range of 2.1% and 14.8%. The method is a simple, rapid and highly efficient one to determine organic phosphorus pesticide residues in scallion.

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Solid-Phase Chemical Synthesis and Oxidative Refolding of Hainantoxin-Ⅲ PI Jianhui, QUAN Miaohua, ZENG Xiongzhi 2007, 25 (3):  399-403.  Abstract ( 2192 )   [Full Text(HTML)] () PDF (524KB) ( 704 )   Hainantoxin-III (HNTX-III) was synthesized using solid-phase chemical method with Fmoc-protected amino acids. Reversed-phase high performance liquid chromatography (RP-HPLC) was used to monitor the oxidative refolding of linear HNTX-III. It is found that the best refolding yield for 0.1 g/L linear HNTX-III could be obtained in double-distilled aqueous solution at pH 7.5 containing 1.0 mol/L L-arginine, 1.0 mmol/L reduced glutathione (GSH), and 0.1 mmol/L oxidized glutathione (GSSG). The relative molecular mass of the refolded HNTX-III was determined to be 3607.68 by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Only one peak was found in the RP-HPLC chromatogram for the mixed sample of native HNTX-III and refolded HNTX-III at ratio of 1∶1, and the effect of refolded HNTX-III on neuromuscular transmission in isolated mouse phrenic nerve-diaphragm preparations was almost same as that of native HNTX-III. The results indicate that refolded HNTX-III had the same structure and biological activities as the native HNTX-III.

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Determination of Five Macrolide Antibiotic Residues in Royal Jelly Samples by Using High Performance Liquid Chromatography Tandem Mass Spectrometry XIE Wen, DING Huiying, XI Junyang, QIAN Yan, HUANG Leifang 2007, 25 (3):  404-407.  Abstract ( 2168 )   [Full Text(HTML)] () PDF (263KB) ( 902 )   The macrolides are lipophilic molecules having a central lactone ring bearing 12 to 20 atoms to which several amino and/or neutral sugars are bound. They are broad spectrum antibiotics active against Gram-positive bacteria and mycoplasmas, as well as some Gram-negative organisms and members of the chlamydia group. Macrolides are a group of antibacterial compounds that have been widely used in medical and veterinary practices. A method of high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was developed for the confirmation of five macrolide antibiotic residues (spiramycin, oleandomycin, tylosin, roxithromycin, josamycin) in royal jelly samples. Trichloroacetic acid solution was used to precipitate the protein in the sample. The upper layer solution was extracted with acetonitrile. Then it was cleaned up with a C18 column. The one precursor/two product ion transitions for each macrolide antibiotics were monitored. The results show that the working curves for five macrolide antibiotics were linear in the range of 0.002-0.05 mg/L by HPLC-MS/MS in selective ion monitoring model. The limits of quantitation of the antibiotics in royal jelly were all 20 μg/kg. The recoveries were between 73.0%-90.2% at three spiked levels （20, 100 and 200 μg/kg for each macrolide antibiotic）, and the relative standard deviations were between 5.6%-10.5%.

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Investigation of the Pyrolysis Behavior of 4-Oxo-β-Damascone by On-Line Pyrolysis Gas Chromatography-Mass Spectrometry WU Yiqin, YANG Liu, LIU Fang, MIAO Mingming, ZHU Hongyou, MAO Deshou, 2007, 25 (3):  408-412.  Abstract ( 2353 )   [Full Text(HTML)] () PDF (515KB) ( 938 )   The pyrolysis behavior of an essence, 4-oxo-β-damascone, was investigated using an on-line pyrolysis gas chromatography-mass spectrometry (PyGC/MS). In helium atmosphere, the compound was pyrolyzed at 350, 450, 550, 650, 700, and 750 ℃, separately. The pyrolysis products were directly introduced into GC/MS with 1.03×106 Pa He and were qualitatively and semi-quantitatively analyzed. At the six pyrolysis temperatures mentioned above, 3, 7, 15, 33, 42 and 45 products were detected and their relative contents were 96.25%, 85.44%, 87.18%, 78.37%, 78.29% and 83.13%, respectively. The results indicated that the pyrolysis temperature directly affected the pyrolysis pattern and the relative content of the products. A total of 54 products were identified, including β-damascone, 4-oxo-β-ionone, 3,4,4-trimethyl-2-cyclohexen-1-one and 2,5,5-trimethyl-cyclohex-3-en-1-one. At 550 ℃, only a small portion of the parent compound was pyrolyzed. At 750 ℃, the compound was completely pyrolyzed, with a conversion of 99.74% and 45 products were given. Moreover, with the elevation of the pyrolysis temperature, complex pyrolysis products were formed, and harmful substances, such as benzene, toluene, anthracene and phenanthrene were identified. According to the relative content and the category of the pyrolysis products, the pyrolysis mechanism of 4-oxo-β-damascone is further discussed with the conclusion that the pyrolysis of this compound might take place via 4 different pathways. The investigation gave an exemplification for the transfer behavior of tobacco essence in the cigarette burning process, and provided a reliable theoretical foundation for the perfume reinforcement technology in tobacco products, contributing to the development of cigarette products with better aroma and taste.

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Characterization of the Reaction Products from Pine Gum Catalytic Disproportionation by Gas Chromatography/Mass Spectrometry WANG Linlin, XU Xu, CHEN Xiaopeng, SUN Wenjing, TONG Zhangfa 2007, 25 (3):  413-417.  Abstract ( 2376 )   [Full Text(HTML)] () PDF (363KB) ( 871 )   The reaction products of a new pine gum catalytic disproportionation were analyzed by gas chromatography/mass spectrometry (GC/MS) using HP-5MS flexible quartz capillary column. Forty-five peaks were separated and 38 compounds were identified. It was found that the main product of the disproportionated turpentine from pine gum was p-cymene (16.26%), and the main chemical compositions of disproportionated rosin were dehydroabietic acid (41.58%) and hydrogenation resin acid (21.43%). In addition, the mechanism of pine gum catalytic disproportionation was preliminarily investigated based on the analysis results. The results showed that resin acids of pine gum produced the intermolecular hydrogen transfer reaction, and the dehydrogenation of resin acids was promoted by the solvent effect of terpenes. It was indicated that the double ring monoterpene in the turpentine of pine gum was converted into monocyclic ring monoterpene by ring-opening isomerization reaction, and then into p-cymene by catalytic dehydrogenation in the presence of resin acids. Based on the results it was also found that the superfine disproportionated rosin and high contents of p-cymene could be obtained from pine gum using the novel process.

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Determination of Difenoconazole Residue in Foods by Gas Chromatography-Negative Chemical Ionization Mass Spectrometry SHEN Weijian, YANG Wenquan, SHEN Chongyu, ZHAO Zengyun, XU Jinzhong, DING Tao 2007, 25 (3):  418-421.  Abstract ( 4605 )   [Full Text(HTML)] () PDF (225KB) ( 1340 )   A method is presented for the determination of difenoconazole residue in all kinds of foods by solid phase extraction-gas chromatography-negative chemical ionization mass spectrometry (SPE-GC-MS/NCI). Difenoconazole residue was extracted with ethyl acetate from different samples, such as perilla leaves, carrots, spinach powder, rice, gram, jasmine flower tea, oolong tea, strawberries, sauce, bee honey, beef, chicken and eels, etc. The extracts were cleaned-up by active carbon SPE column connected to alumina neutral SPE column or Florisil SPE column only. Analytical screening was determined by the technique of GC-MS/NCI on selected ion monitoring mode. The recoveries of difenoconazole in most samples were in the range from 70% to 120% at three spiked levels, 0.01 mg/kg, 0.04 mg/kg and 0.10 mg/kg, and the relative standard deviations (RSDs) were below 9.5%. The linearity of the method is good from 0.02 to 1.00 mg/L, and limit of detection (LOD) was 0.0005 or 0.0010 mg/kg for different type samples. The method is selective without interference and is suitable for determination and conformation of difenoconazole residue in all kinds of foods.

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Extraction and Identification of Volatile Constituents in the Flowers of Aglaia odorata Lour. ZHANG Junsong, YAO Ermin, WANG Jianmin, XU Ruyan, 2007, 25 (3):  422-424.  Abstract ( 2770 )   [Full Text(HTML)] () PDF (155KB) ( 778 )   The volatile constituents in the flowers of Aglaia odorata were extracted by supercritical CO2 fluid under 25 MPa and 40 ℃ for 80 min. The oil yield was 2.64%. These volatile constituents were separated and identified by capillary gas chromatography-mass spectrometry (GC-MS). Experiments were performed on an Agilent 6890 GC Chromatograph with Agilent 5973N Mass Selective Detector. The GC separation conditions was carried out on an HP-5MS capillary column (60 m×250 μm, 0.25 μm); oven temperature, 50 ℃ (held for 2 min) to 280 ℃ at a rate of 5 ℃/min, and held for 8 min; split ratio, 1∶10; injector temperature, 270 ℃. Mass spectra were collected in the scan range of m/z 50-550. The measurements were performed with electron bombardment ion （EI） source with electron energy of 70 eV and electron multiplier voltage of 1.65 kV. The results showed that 54 peaks were separated and 48 compounds were identified for the essential oil extracted from Aglaia odorata L. There were 18 terpenes, 12 esters and other constituents in the volatile oil fraction. The constituents in the oil fraction were α-humulene, followed by ethyl linolenate, germacrene D, β-elemene, copaene, caryophyllene, methyl jasmonate, β-humulene-7-ol, ethyl palmitate, etc.

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Identification of Volatile Organic Compounds in the Manures of Cow, Hog and Chicken by Solid Phase Microextraction Coupled with Gas Chromatography/Mass Spectrometry HUANG Jun, HE Jin, ZHANG Jibin, YU Ziniu, 2007, 25 (3):  425-429.  Abstract ( 2858 )   [Full Text(HTML)] () PDF (297KB) ( 876 )   A simple, rapid and solvent-free method, headspace solid phase microextraction (HS-SPME) coupled with gas chromatography/mass spectrometry (GC/MS) has been developed for the identification of volatile organic compounds (VOCs) in the manures of cow, hog and chicken. The optimization of SPME conditions and parameters on the effectiveness of analysis and identification of the VOCs has been investigated. The optimal procedures were that 10 g of solid manure and 50 mL of solution saturated by NaCl were added into a vial of 100 mL, stirred at 800 r/min, equilibrated for 30 min and extracted for 30 min at 60 ℃ using a PDMS/DVB fiber, and desorbed at 280 ℃ for 5 min. A total of sixty-six compounds from these three kinds of manures were identified using the NIST library of compound mass spectra. In cow manure, a total of forty-four VOCs were identified as compared to forty in hog manure and forty-one in chicken manure, and among them, sixteen compounds were found to be commonly present. The main components found were: 3-methyl-dodecane (8.18%, peak area percentage), 1-methyl-naphthalene (7.97%) and 3-methyl-1H-indole (7.81%) for the cow manure; 3-methyl-1H-indole (48.89%), 4-methyl-phenol (24.68%) and indole (7.30%) for the hog manure, and 4-ethyl-phenol (13.80%), 4-methyl-phenol (10.67%) and indole (9.77%) for the chicken manure. The results of this study show that HS-SPME-GC/MS is an excellent analytical technique that can be used to identify and analyze VOCs from animal manures. These results also provide a scientific basis to identify off-flavor from animal manures in livestock and poultry industry.

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Simultaneous Determination of Iodate, Chlorite and Bromate in Bottled Drinking Water by Ion Chromatography with Post-Column Reaction and UV Detection ZHOU Yiqi, WANG Zijian, XU Yiping, MA Mei 2007, 25 (3):  430-434.  Abstract ( 2089 )   [Full Text(HTML)] () PDF (630KB) ( 815 )   Iodate, chlorite and bromate in bottled water are disinfectant by-products (DBPs) from ozonation. The established methods for simultaneous determination of iodate, chlorite and bromate are mostly based on pre- or post-column chemical reaction in which the target compound was converted to another easily detectable species. However, the procedure suffers from several time-consuming reaction steps that involve multiple chemicals, or where the reagents themselves are toxic. In the present study, a rapid, highly sensitive, precise and accurate method was established, and a post-column reaction with sodium nitrite and acid solution of potassium bromide was employed to enhance sensitivity and to reduce interferences. Under optimized conditions, the method limits for iodate, chlorite and bromate were 0.5, 0.4 μg/L and 0.1 μg/L, respectively. Percentage recoveries of iodate, chlorite and bromate varied from 70.8% to 98.0%, 92.4% to 100% and 93.2% to 104.1% respectively with different spiked water samples. The proposed method was demonstrated for detecting the concentrations of iodate, chlorite and bromate in bottled water produced from different water sources. Results showed that severe bromate contamination was present in bottled mineral water purchased from Beijing supermarket, which used spring water or ground water as the sources.