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Chinese Journal of Chromatography
2006, Vol. 24, No. 5
Online: 30 September 2006

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Preparation of a Concanavalin A Immobilized Affinity Column and Its Application in the Structural Analysis of Ribonuclease B CHEN Gang, BAI Quan, GENG Xindu 2006, 24 (5):  425-431.  Abstract ( 2469 )   [Full Text(HTML)] () PDF (1338KB) ( 1047 )   The research on glycoproteomes represents an interesting field in the functional proteomics research. Affinity chromatography and mass spectrometry are powerful techniques that are used for gaining valuable information on glycoproteomes because glycoproteins and their unusual forms resulting from protein glycosylation can be important indicators of several diseases. In this study, the concanavalin A (Con A) immobilized silica packing was prepared and used for the separation of glycoprotein and glycopeptides. A very low, non-specific adsorption on the Con A affinity column was demonstrated by mass recovery of bovine serum albumin at more than 98.5%. The effect of concentration of methyl-α-D-mannopyranoside (α-Me-D-Man) in the mobile phase and the effect of flow rate on the retention behavior of ribonuclease B (RNase B) were also investigated. The standard glycoprotein RNase B was separated under optimized conditions using 0.2 mol/L α-Me-D-Man in the mobile phase at a flow rate of 0.5 mL/min. Meanwhile, the oligosaccharides and glycopeptides were enriched using a Con A column after digestion of the purified RNase B with peptide-N-glycosidase F (PNGase F) and trypsin. The structure of N-linked glycan and the rate and the site of glycosylation of RNase B were determined by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Glycoproteins and glycopeptides in human serum and digest solution could be separated by this method. The results showed that this method is rapid and sensitive for the purification and characterization of glycoproteins and glycopeptides. Fig.8 Tab.1 Ref.22

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Determination of Metabolites of Nitrofuran Antibiotics in Royal Jelly by High Performance Liquid Chromatography-Tandem Mass Spectrometry DING Tao, XU Jinzhong, SHEN Chongyu, WU Bin, CHEN Huilan,ZHU Chun, ZHAO Zengyun, JIANG Yuan, LIU Fei 2006, 24 (5):  432-435.  Abstract ( 2313 )   [Full Text(HTML)] () PDF (377KB) ( 768 )   Nitrofurans are a group of widely used veterinary antibiotics that have been banned in many countries. This has generated a great deal of interests and demands for assay of nitrofurans in animal food products. To our knowledge, this is the first time that a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been successfully developed for simultaneously analyzing the metabolites of four nitrofuran antibiotics (furazolidone, furaltadone, nitrofurazone and nitrofurantoin) in royal jelly. Trichloroacetic acid solution was used both to precipitate proteins and to provide acidic reaction condition. Four isotope internal standards were utilized to improve the quantitative precision. The limits of detection (LODs) were 0.03 μg/kg for the metabolite of furaltadone and 0.05 μg/kg for the other three metabolites. The limits of quantitation were 0.20 μg/kg for the metabolite of furaltadone and 0.25 μg/kg for the other three metabolites. The linear range was 0.4-20 ng/mL for all the target analytes. The recoveries calibrated by internal standard were in the range of 97.7%-104.8% with the relative standard deviations (RSDs) of 2.7%-9.7%. It showed that this method could meet the requirements of national monitoring plan in China and the Minimum Required Performance Limits (MRPL) set by the European Union.

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Determination of Lincosamide Residues in Honey Using High Performance Liquid Chromatography-Electrospray Tandem Mass Spectrometry XU Jinzhong, WU Bin, DING Tao, SHEN Chongyu, ZHAO Zengyun, CHEN Huilan, JIANG Yuan 2006, 24 (5):  436-439.  Abstract ( 2345 )   [Full Text(HTML)] () PDF (498KB) ( 654 )   An analytical method for the determination of lincosamide antibiotic residues in honey was developed. In the procedure a solid-phase extraction for the isolation of lincomycin and clindamycin from diluted honey samples was employed. The residues of lincomycin and clindamycin were subsequently analyzed by reversed-phase high performance liquid chromatography (RP-HPLC) coupled with electrospray tandem mass spectrometry. Mass spectral acquisition was applied with selective reaction monitoring of two diagnostic transition reactions. The qualitative analysis was based on the retention time, the precursor ion and two product ions, and the quantitation was carried out with intension of the characteristic ion m/z 126. The linear ranges were from 1.0 μg/L to 200 μg/L for lincomycin and clindamycin and the correlation coefficients (r2) were all greater than 0.996. The average recoveries for lincomycin and clindamycin ranged from 80% to 110% in replicate sets of honey samples spiked with the drug concentrations of 1.0, 5.0 and 20.0 μg/kg, and the relative standard deviations (RSDs) were less than 8% for intra-day and 15% for inter-day determinations. The method detection limit and quantitation limit were 0.1 μg/kg and 0.5 μg/kg, respectively. The method is simple and suitable for routine analysis.

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Determination of Multiple Pesticide Residues in Honey Using Gas Chromatography-Mass Spectrometry JIN Zhen, LIN Zhuguang, CHEN Meiyu, MA Yu, TAN Jun, FAN Yulan, WENG Jiachen, CHEN Zhaobin, TU Fengzhang, 2006, 24 (5):  440-446.  Abstract ( 2529 )   [Full Text(HTML)] () PDF (324KB) ( 885 )   An analytical method was developed for the simultaneous determination of 23 pesticide residues in various commercial honeys. Meanwhile, the characteristic ions and fragmentation mechanism of three pesticides in the process of electron ionization mass spectrometry (EI/MS) were evaluated. After the optimization of different parameters such as the extraction solvent, pesticides were extracted from honey with ethyl acetate in an ultrasonic bath, cleaned up on a Florisil column by an elution of mixture of hexane and ethyl acetate (7∶ 3,v/v), and analyzed by gas chromatography-electron ionization mass spectrometry (GC-EI/MS) in the selected ion monitoring mode (SIM) with PCB103 as internal standard. Recovery studies were performed at 50, 100 and 200 μg/kg fortification levels for each pesticide, and the recoveries ranged from 82% to 120% with relative standard deviations between 1.8% and 11.0% for different pesticides. The limit of detection was less than 10.0 μg/kg for all the pesticides. The developed method was linear in the range of 10-500 μg/kg, with correlation coefficients larger than 0.995. Finally, the developed analytical method has been successfully applied to the determination of pesticide residues in several honey samples.

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Determination of 3-Monochloropropane-1,2-Diol in Hydrolyzed Vegetable Proteins and Soy by Solid Phase Extraction and Gas Chromatography/Negative Chemical Ionization-Mass Spectrometry CHEN Jie, WANG Zhiyuan 2006, 24 (5):  447-450.  Abstract ( 2787 )   [Full Text(HTML)] () PDF (553KB) ( 710 )   Solid phase extraction (SPE) and gas chromatographic/negative chemical ionization-mass spectrometric （GC/NCI-MS） method was developed for the determination of 3-monochloropropane-1,2-diol (3-MCPD) in hydrolyzed vegetable proteins (HVP) and soy. The optimized conditions for the extraction and cleanup of 3-MCPD on an Aoisa-HBL column were investigated. The extract with hexane-ethyl acetate was evaporated to nearly dry by N2 at 40 ℃ and derivatization was performed with 1-(heptafluorobutyryl) imidazole at 70 ℃ for 30 min. The mixture was then injected into a gas chromatograph with a DB-5MS capillary column, detected by a mass spectrometer in negative chemical ionization and selected ion monitoring mode (NCI/SIM) and quantified with external standard calibration. The limit of quantitation (LOQ) for 3-MCPD was 0.5 μg/kg. The average recovery was in a range of 92.2%-97.4% with a relative standard deviation range of 3.6%-10.9%. The results indicated that the method could be used for the sensitive and accurate determination of 3-MCPD in foods and agriculture products.

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Microstructural Characterization for Pyrolysis Hydrogenation Fragments in Polyethylene by Pyrolysis Hydrogenation Gas Chromatography/Mass Spectrometry DING Junkai, SONG Ming, HUANG Li 2006, 24 (5):  451-455.  Abstract ( 1887 )   [Full Text(HTML)] () PDF (614KB) ( 579 )   The microstructural characterization of 47 samples, respectively of high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), copolymer of ethylene and α-olefins, was performed by pyrolysis hydrogenation gas chromatography/mass spectrometry (Py-H-GC/MS) with 10% Pt on 80-100 mesh Diasolid H as a hydrogenation catalyst. The samples were obtained from 12 domestic plants and 12 plants abroad as well. The sample sizes ranging from 30 to 80 μg were pyrolyzed at 770 ℃ in a flow of hydrogen carrier gas. It was found that short methyl branches as the characteristic isoalkanes of pyrolysis hydrogenation in polyethylene would be related closely to the different classes of polyethylene. The microstructural characterization has been carried out by means of Py-H-GC/MS, according to the relative amount of the four short methyl branches, 5-methyldodecane (5-MC12), 4-methyldodecane (4-MC12), 2-methyldodecane (2-MC12) and 3-methyldodecane (3-MC12) existed in C12-C13 isoalkanes. The Py-H-GC/MS technique will be providing further scientific evidences for the characterization of polyethylene plastics in forensic science.

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Synthesis of 1-［2-(p-Toluenesulfonate)Ethyl］-2-Phenylimidazole ［4,5-f］ 9,10-Phenanthrene and Its Application for Analysis of Long-Chain Fatty Acids ZHAO Xian’en, SUO Yourui, DING Chenxu, ZHU Fang, SUN Jing, ZHAO Wenchen, SUN Xuejun, YOU Jinmao, 2006, 24 (5):  456-461.  Abstract ( 2516 )   [Full Text(HTML)] () PDF (706KB) ( 959 )   A simple and sensitive method for the determination of long-chain free fatty acids (FFAs) using 1-［2-(p-toluenesulfonate)ethyl］-2-phenylimidazole ［4,5-f］ 9,10-phenanthrene (TSEPIP) as pre-column derivatization reagent by reversed-phase high performance liquid chromatography with fluorescence detection and mass spectrometric identification was developed. Eleven long-chain (C20-C30) FFA derivatives were separated on Eclipse XDB-C8 column with a good baseline resolution. Studies on derivatization conditions indicate that FFA reacts rapidly and smoothly with TSEPIP in the presence of K2CO3 catalyst at 90 ℃ in N, N-dimethylformamide solvent to give the corresponding sensitively fluorescent derivatives with maximal yields close to 100% with a 5-fold molar reagent excess. The identification of 11 FFA derivatives was carried out by online post-column mass spectrometry with atmospheric pressure chemical ionization source in positive-ion mode. The contents of 11 FFAs in soil and three bryophytes (Homomallium connexum (Card.) Broth., Actinothuidium hookeri, Neckera pennata) were determined. The results indicate that the bryophyte plants enrich an abundance of FFAs from soil. The excitation and emission wavelengths of fluorescence detection were set at 260 nm and 380 nm, respectively. Linear correlation coefficients for the most FFA derivatives were higher than 0.9996, and the detection limits (at signal-to-noise of 3∶1) were 26.19-76.67 fmol. The method is sensitive and reproducible for the determination of long-chain FFAs in real samples.

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Determination of Residues of Three Stilbene Drugs in Animal Tissues Using Gas Chromatography-Mass Spectrometry WU Yinliang, LIU Suying, HOU Dongjun, SHEN Jianzhong, WANG Hai, SHAN Jihao 2006, 24 (5):  462-465.  Abstract ( 2315 )   [Full Text(HTML)] () PDF (325KB) ( 615 )   A method has been developed to determine residual stilbenes such as diethylstilbestrol (DES), dienestrol (DIS) and hexestrol (HS) in animal tissues using solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). The procedures for extraction, cleanup on an LC-Si solid phase extraction cartridge and derivatization of stilbenes were established and optimized. The analytes were detected by mass spectrometer with electron impact source in selected ion monitoring mode(EI/SIM), and quantified with an external standard calibration curve method. Linear calibration curves were obtained in the concentration ranges from 5 to 500 μg/L for HS and from 10 to 1 000 μg/L for DES and DIS(the correlation coefficients were above 0.99). Recoveries of the stilbenes were 73.0%-86.5%, and the relative standard deviations were between 1.0% and 7.2%. The limits of detection were 0.30 μg/kg for cis-DES, 0.10 μg/kg for trans-DES and HS and 0.15 μg/kg for DIS in pork and swine liver.

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Optimum Separation Conditions of Catechin Compounds by HCI Program in Reversed-Phase High Performance Liquid Chromatography JIN Yinzhe, ROW Kyung Ho 2006, 24 (5):  466-470.  Abstract ( 2086 )   [Full Text(HTML)] () PDF (342KB) ( 830 )   An efficient optimization method was used to separate catechin compounds by reversed-phase high performance liquid chromatography (RP-HPLC). The binary mobile phase of water and methanol was utilized with the buffer of acetic acid (AA). The elution profiles were calculated by the plate theory based on the linear and quadratic equations of retention factor, ln k =ln kw +SF, k=A+B/F, ln k=L+MF+NF2, where F is the volume fraction of methanol in the mobile phase. The retention theory was modified to calculate the elution profile in both isocratic and gradient modes. Based on the retention theory, elution profiles were predicted by introducing the concept of solute migration in the mobile phase with the linear and quadratic dependence of ln k in terms of the organic modifier content. Using the HCI program (a software designed by Inha University), the recommended experimental conditions of mobile phase composition and gradient step were suggested, and the elution profiles calculated by the quadratic relationship of ln k showed better coincidence with the experimental data than the linear correlation did. The calculated results of mobile phase condition for separation of catechin compounds suggested that the mobile phase composition was 0.1% AA in water/0.1% AA in methanol, 75/25 (v/v), then after 15 min, the composition was linearly changed to 50/50 (v/v) in 10 min and held at the isocratic mode to the end. In the experimental conditions, the agreement between the experimental elution profiles and the calculated values of eluted concentration was relatively good.

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Monitoring Sulfadiazine and Sulfamethazine Residues in Eggs Using Polymer Monolith Microextraction Coupled with High Performance Liquid Chromatography WEN Yi, WANG Ying, FENG Yuqi 2006, 24 (5):  471-474.  Abstract ( 2036 )   [Full Text(HTML)] () PDF (415KB) ( 729 )   The method for the quantitative monitoring of sulfadiazine and sulfamethazine residues in eggs was established by coupling polymer monolith microextraction (PMME) with high performance liquid chromatography and ultra-violet detection (HPLC/UV). The PMME is an effective sample preparation technique, which has been developed on the basis of in-tube solid-phase microextraction. A poly (methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column was selected as an extraction device. To obtain the optimum extraction efficiency, several parameters related to PMME, including extraction flow-rate, extraction volume, and pH value of the sample matrix were investigated. The sample solution can be directly injected into the device for extraction after simple extraction with ethanol, dilution with phosphate buffer solution, and centrifugation. Because of the high extraction capacity of the monolith column, low detection limits (S/N=3) (8.8 ng/g for sulfamethazine and 11.2 ng/g for sulfadiazine) and quantification limits (S/N=10) (29.3 ng/g for sulfamethazine and 37.5 ng/g for sulfadiazine) were obtained. The method showed good linearity ranging from 50 to 5000 ng/g. Excellent reproducibility of the method was found by intraday and interday precisions, yielding the relative standard deviations of ≤7.6% and ≤8.2%, respectively. Recoveries for them were higher than 65%. Compared with the standard methods used in China, improved results were obtained using this method. The proposed method was proved to be simple, rapid, sensitive, and competent in monitoring sulfadiazine and sulfamethazine residues in eggs.

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Simultaneous Determination of Four Carotenoids in Health Products by Reversed-Phase High Performance Liquid Chromatography LI He, CHEN Min, ZHU Lei, LIU Lijuan, WANG Jingyu 2006, 24 (5):  475-478.  Abstract ( 2100 )   [Full Text(HTML)] () PDF (292KB) ( 623 )   A method was established for the determination of carotenoids （lutein, zeaxanthin, lycopene, β-carotene） in health products by reversed-phase high performance liquid chromatography (RP-HPLC). The extraction methods of carotenoids from different types of samples were also established. Separation and quantification was achieved by using a DiamonsilTM C18 column (250 mm×4.6 mm i.d., 5 μm), and a mobile phase of acetonitrile and ethyl acetate were used with the following gradient elution: 100% acetonitrile at the first 15 min, then ethyl acetate increased to 100% in the next 10 min, at last 100% acetonitrile for 5 min with a flow rate of 1 mL/min, temperature of 25 ℃ and monitored with a photodiode array detector at 450 nm. The external standard calibration curves were used for quantification. There were good linear correlations for the four carotenoids. The correlation coefficients were between 0.9994 and 0.9997. The detection limits were 0.4-0.5 mg/L. The recoveries of four carotenoids in tablet samples were 95.3%-98.7% with the relative standard deviations (RSDs) of 0.89%-2.0%. The recoveries of four carotenoids in powder samples were 93.7%-98.8% with RSDs of 0.89%-2.8%. The recoveries of four carotenoids in oil samples were 97.1%-99.2% with RSDs of 0.42%-1.2%. This method is simple, fast, accurate and convenient. It can be used as one of the reliable means for quantitative determination of carotenoid in health products.

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Isolation and Determination of Homoeriodictyol-7-O-β-D-Glycoside in Viscum coloratum ZHAO Yunli, MA Mingyan, GAO Xiaoxia, LIU Tao, YU Zhiguo, BI Kaishun 2006, 24 (5):  479-481.  Abstract ( 2165 )   [Full Text(HTML)] () PDF (237KB) ( 588 )   The homoeriodictyol-7-O-β-D-glycoside was isolated from Viscum coloratum and identified by mass spectrometry and nuclear magnetic resonance (NMR) (1H NMR and 13C NMR). A method for determination of homoeriodictyol-7-O-β-D-glycoside in Viscum coloratum was developed by using a Kromasil C18 column (200 mm×4.6 mm i.d., 5 μm) with a mixture of acetonitrile and 0.5% glacial acetic acid solution (18∶82, v/v) as mobile phase at a flow rate of 1.0 mL/min. The detection wavelength was set at 284 nm and temperature was set at 30 ℃. The volume of injection was 10 μL. Good linear relationship (r=0.9997) between the mass concentration and the peak area of homoeriodictyol-7-O-β-D-glycoside was obtained in the range of 1.0-32.0 mg/L. The recoveries were found to be in the range of 96.0%-100.1%. The results of the experiments demonstrated that the established method is rapid and simple with good accuracy and reproducibility. The method is suitable for the quality control of Viscum coloratum from different sources.

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Isolation and Purification of Puerarin from Puerarin Extractive by Chelate Complex Chromatography PAN Jian, YUAN Chuanxun, DAI Yuqing 2006, 24 (5):  482-485.  Abstract ( 2504 )   [Full Text(HTML)] () PDF (329KB) ( 625 )   Puerarin, an isoflavone compound, is an important ingredient in traditional Chinese medicine, which has the good medical effects on hypertension and angina. A new type of separation and purification method for isolating puerarin was developed using chelate complex chromatography. The stationary phase was prepared with silica gel containing 7% of Cu(OAc)2 in the chloroform. After the chloroform was evaporated, it was used as chelate complex chromatographic stationary phase to purify puerarin extractive. Pure puerarin was obtained when a mixture of chloroform and methanol (10∶1, v/v) was used as eluent. In comparison with a common silica gel column, the chelate complex chromatographic column was more convenient and efficient. The purity and recovery of puerarin, and column capacity were improved 11%, 12% and 200%, respectively. Under the optimized experimental conditions， the purity of puerarin could be as high as 93％with a recovery of 92%.

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Simultaneous Determination of Five Isoflavonoids in Commercial Radix Astragali by High Performance Liquid Chromatography WANG Xiaohui, LIU Tao, LI Qing, CHEN Xiaohui, BI Kaishun 2006, 24 (5):  486-488.  Abstract ( 2000 )   [Full Text(HTML)] () PDF (209KB) ( 1137 )   A reversed-phase high performance liquid chromatographic method (RP-HPLC) was developed for the simultaneous analysis of five isoflavonoids of Huangqi, the roots of Astragalus mongholicus. HPLC determination was performed on a Diamonsil C18 column (200 mm × 4.6 mm i.d., 5 μm) and detected at 230 nm. The mobile phase consisted of (A)acetonitrile and (B)water. Gradient program was adopted as follows: 0-25 min from 17%A to 31%A, 25-45 min 35%A. The flow rate was maintained at 1.0 mL/min. The method was proved to be linear in the ranges of 20.12-201.2 mg/L (r=0.9992), 4.62-46.2 mg/L (r=0.9997), 4.86-48.6 mg/L (r=0.9997), 9.24-92.4 mg/L (r=0.9995) and 6.92-69.2 mg/L (r=0.9995)for the five isoflavonoids, calycosin-7-O-β-D-glucoside, formononetin-7-O-β-D-glucoside, 9,10-dimethoxypterocarpan-3-O-β-D-glucoside, calycosin and formononetin, respectively. The recoveries were greater than 94%, and relative standard deviations were less than 3.2%. The method has been successfully applied to the simultaneous determination of the five isoflavonoids of radix astragali.

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Determination of Puerarin in Kangshen Granule by Reversed-Phase High Performance Liquid Chromatography CHEN Man, SHI Jian, WANG Lili, GENG Xindu 2006, 24 (5):  489-491.  Abstract ( 2158 )   [Full Text(HTML)] () PDF (294KB) ( 689 )   Kangshen granule, containing 12 kinds of traditional Chinese medicine, has complex composition. A new method for the determination of puerarin in Kangshen granule was developed using reversed-phase high performance liquid chromatography coupled with matrix assisted laser desorption ionization time of flight mass spectrometry and ultraviolet detection (RP-HPLC/MALDI-TOF MS/UV). The sample was separated by RP-HPLC with a non-linear gradient elution, and then was qualitatively detected by mass spectrometry to identify the puerarin peak. The chromatographic process was performed on a YMC-ODS column under the optimized conditions with a mobile phase consisting of methanol, water and 0.1% TFA, and detected at 250 nm. The linear range of puerarin was from 0.132 to 1.32 μg (r=0.9997). The recovery was higher than 103% and the relative standard deviation was lower than 2.0% (n=6). The puerarin content in Kangshen granule sample was determined and the puerarin content was 3.09 mg/g. The method is simple and feasible for the determination of puerarin with a good repeatability. The method can be used for quality control of Kangshen granule.

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Determination of Corosolic Acid in Eriobotrya japonica Leaves by Reversed-Phase High Performance Liquid Chromatography HU Changping, CHEN Longsheng, XIN Yang, CAI Qunxing 2006, 24 (5):  492-494.  Abstract ( 2050 )   [Full Text(HTML)] () PDF (451KB) ( 717 )   Corosolic acid is clinically proven to activate cell glucose-transporter “shuttles” and thus helps balance blood glucose levels. A method was developed for the determination of corosolic acid in Eriobotrya japonica leaves by reversed-phase high performance liquid chromatography (RP-HPLC). The peak of corosolic acid in Eriobotrya japonica leaves was qualitatively analyzed by comparing the retention times and mass spectra of corosolic acid standard and the extract on HPLC-mass spectrometry (MS). Eriobotrya japonica leaves were extracted thrice for 3.0 h at 90 ℃ with 90% ethanol. The extract was concentrated and deposited by water to remove the impurity which interfered the determination. The deposit was dissolved by methanol and separated on an ODS column (250 mm×4.6 mm i.d., 5 μm). Methanol-1.0%acetic acid (88∶12, v/v) was used as the mobile phase with a flow rate of 0.8 mL/min. The detection wavelength was 215 nm. The linearity was good within the range of 1.0-6.0 μg (r=0.9999). The corosolic acid content of Eriobotrya japonica leaves from Huangshan was 0.36%. The average recovery of corosolic acid was 99%. The method is simple, rapid, accurate and reliable for the determination of corosolic acid in Eriobotrya japonica leaves.

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Simultaneous Determination of Monochlorophthalic Anhydride and Monochlorophthalic Acid in Substrates by High Performance Liquid Chromatography YUAN Xiuling 2006, 24 (5):  495-498.  Abstract ( 1820 )   [Full Text(HTML)] () PDF (357KB) ( 702 )   A high performance liquid chromatographic method has been developed for the simultaneous determination of 3-chlorophthalic anhydride, 4-chlorophthalic anhydride, 3-chlorophthalic acid and 4-chlorophthalic acid. The operating conditions were a Luna-C18 column at 30 ℃, methanol-0.15 mol/L ammonium dihydrogen phosphate solution (42∶58, v/v) as mobile phase with flow rate of 0.8 mL/min, ultra-violet detection at 240 nm. An external standard method was used. Samples were esterified with absolute ethanol at 80-100 ℃ for 15 min. 3-Chlorophthalic anhydride and 4-chlorophthalic anhydride were respectively converted to two isomers of monochloro-O-carboxyl ethyl benzoate, and the monochlorophthalic acids were not esterified under the reaction conditions. The results demonstrated that the recoveries were 99.1%-101.5%; the relative standard deviations ranged from 0.48% to 0.87%; the linear ranges were 3.12-312.4 mg/L, 2.96-222.3 mg/L, 1.86-186.4 mg/L, 1.41-141.0 mg/L for 3-chlorophthalic anhydride, 4-chlorophthalic anhydride, 3-chlorophthalic acid and 4-chlorophthalic acid, respectively. The method was simple, accurate and fast. The six components could be separated completely in about 20 min.

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Simultaneous Determination of Trilobolide-6-O-Isobutyrates A and B in Wedelia trilobata by Gas Chromatography HUANG Xuesong, OU Shiyi, TANG Shuze, FU Liang, WU Jianzhong 2006, 24 (5):  499-502.  Abstract ( 1948 )   [Full Text(HTML)] () PDF (355KB) ( 668 )   A simple, sensitive, and specific gas chromatographic (GC) method was developed to determine the main bioactive sesquiterpene lactones, trilobolide-6-O-isobutyrates A and B (TBO-A and TBO-B), in Wedelia trilobata, a useful folk herb. A commercially available HP-5 capillary column (30 m×0.25 mm i.d.×0.25 μm) was utilized for the direct determination of TBO-A and TBO-B in W. trilobata. Calibration curves were obtained by spiking authentic compounds and the internal standard (ferulic acid) into W. trilobata samples before extraction. Extraction was carried out by refluxing the dried herb (0.5 g) for 1 h in methanol (25 mL). All calibration curves showed good linear regressions (r2>0.992) within test ranges. The assay was reproducible and accurate with the overall intraday and interday relative standard deviations and accuracies of less than 10% and more than 90%, respectively. The developed GC method was successfully utilized to analyze the TBO-A and TBO-B in aerial parts and flowers of W. trilobata, indicating that it was suitable for the quality control of this commonly used herb and related traditional Chinese medicines.

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Determination of Phthalic Acid Esters in Textiles by Solid Phase Extraction-Gas Chromatography NIU Zengyuan, YE Xiwen, FANG Liping, XUE Qiuhong, SUN Zhongsong 2006, 24 (5):  503-507.  Abstract ( 2656 )   [Full Text(HTML)] () PDF (422KB) ( 991 )   A method was established for the simultaneous determination of some phthalic acid esters， namely, dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPrP), dibutyl phthalate (DBP), diamyl phthalate (DAP), dihexyl phthalate (DHP), benzyl-n-butyl phthalate (BBP), di-(2-ethylhexyl)phthalate (DEHP), dicyclohexyl phthalate (DCHP), di-n-octyl phthalate (DNOP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP) in textiles by solid phase extraction (SPE) coupled with gas chromatography (GC). The phthalic acid esters in textiles were extracted by Soxhlet extraction with hexane, the extracts were then cleaned up and enriched by a strong anion exchange (SAX) SPE cartridge. The parameters affecting the purification efficiency of SPE cartridge, such as solvent conditioning, rinsing, and elution, were studied. Conditioning with 5 mL hexane and rinsing with 3 mL isooctane were proved to be the optimal conditions. Of the several solvent ratios (ethylacetate in hexane) used for selective elution of phthalic acid esters from the SAX SPE cartridge, the 15% (v/v) content for ethylacetate in hexane gave the best result. Under the optimized conditions, the recoveries of phthalic acid esters for spiked standards (n=7) were 86.3%-102.7%, and the relative standard deviations (RSDs) were less than 5%. In this method the detection limits for DMP, DEP, DPrP, DBP, DAP, BBP, DCHP, DEHP, DNOP were all below 1 mg/kg, and the detection limits for DINP and DIDP were 1.74 mg/kg and 1.55 mg/kg respectively. This SPE-GC method is sensitive, accurate and suitable for the analysis of phthalate environmental hormones in textiles.

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Detection of Acetylbritannilactone in Inulicin Ingredients and Dynamic Change in Vivo by Micellar Electrokinetic Capillary Chromatography ZHAO Jingshan, WEN Jinkun, HAN Mei 2006, 24 (5):  508-512.  Abstract ( 2265 )   [Full Text(HTML)] () PDF (3913KB) ( 628 )   Determination of Acetylbritannilactone in Inulicin and Rat Plasma by Micellar Electrokinetic Capillary Chromatography with On-Line Sweeping Concentration Technique

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Separation of Sitafloxacin Epimers by Capillary Electrophoresis YUAN Pei, LIN Lei, FAN Qi, ZENG Linggao 2006, 24 (5):  513-515.  Abstract ( 2003 )   [Full Text(HTML)] () PDF (368KB) ( 779 )   Sitafloxacin epimers were separated by capillary zone electrophoresis using γ-cyclodextrin(γ-CD) and D-phenylalanine (D-Phe) as chiral selector．The effects of the concentrations of γ-CD, D-Phe, Cu2+ and pH of buffer were investigated．An uncoated fused-silica capillary of 50 μm i.d. and 60 cm (effective length 52.5 cm) was used．The capillary temperature was maintained at 25 ℃．Samples were injected under a pressure of 7 kPa for 5 s and separated at 15 kV．A baseline separation of sitafloxacin epimers was achieved with a background electrolyte of 10 mmol/L KH2PO4-K2HPO4 (pH 4.5), 10 mmol/L CuSO4, 20 mmol/L γ-CD and 10 mmol/L D-Phe．The linear range for sitafloxacin was 32-400 mg/L (0.996)．The relative standard deviations (RSDs) of migration time and peak area were less than 1.9% and 3.8% respectively．This method can be applied in qualitative and quantitative analysis for sitafloxacin epimers.

专论综述

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Developments of Liquid-Phase Microextraction Based on Hollow Fiber WANG Chun, WU Qiuhua, WANG Zhi, HAN Dandan, HU Yanxue 2006, 24 (5):  516-523.  Abstract ( 2431 )   [Full Text(HTML)] () PDF (549KB) ( 710 )   The liquid-phase microextraction (LPME), based on disposable hollow fiber, has been developed to be a new environmentally benign sample preparation technique which incorporate sampling, extraction and concentration into a single step. The novel technique can be easily manipulated in combination with high performance liquid chromatography, gas chromatography and capillary electrophoresis, and can provide excellent sample clean-up effect and high degree of extraction recovery and enrichment. It is proved to be simple, low-cost and virtually solvent-free. The extraction set-up, extraction mode, basic principles and recent applications of the hollow fiber-based liquid-phase microextraction are reviewed.

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Application of Gas Chromatography in Research of Biodiesel Processing LI Changxiu, YANG Haiying, WANG Liqin, TIAN Songbai 2006, 24 (5):  524-528.  Abstract ( 2367 )   [Full Text(HTML)] () PDF (467KB) ( 1209 )   Applications of gas chromatography in the research of biodiesel processing are reviewed with 27 references, including the analysis of fatty acid methyl esters (FAME) in the reaction products and final biodiesel, the determination of mono-, di- and tri-glycerides, the contents and distribution of free fatty acids, and the determination of trace methanol in biodiesel. The effects of various factors for analysis of the reaction products are discussed, such as injection mode, column type and silylation. A method for the determination of trace methanol in biodiesel products with dual-columns and pressure backflush system is proposed. 1-Propanol was used as the internal standard. After methanol and 1-propanol entered the analytical column through pre-column, the pressure was changed to backflush the heavy components through the split vent. A polar PEG-20M column was applied for the analysis of the contents and distribution of FAME in biodiesels from 8 different vegetable oils.

技术应用

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Determination of the malachite green, crystal violet and its metabolites residues in aquatic animals by using LC-MS/MS XIE Wen, DING Huiying, XI Junyang, HUANG Leifang 2006, 24 (5):  529-530.  Abstract ( 1894 )   [Full Text(HTML)] () PDF (253KB) ( 953 )

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Enantioseparation of 1,2-Diphenylethylenediamine and its Schiff Base Condensated with Dehydroacetic Acid by High Performance Liquid Chromatography ZHANG Lei, XIE Baozhu, RUAN Yuanping 2006, 24 (5):  531-532.  Abstract ( 2543 )   [Full Text(HTML)] () PDF (1045KB) ( 720 )

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RP-HPLC Determination of Danshensu and Protocatechuic aldehyde in Guanxinning Injections CAO Dong, HUANG Xiru, LIU Weina, YANG Yajun, JI Guorong 2006, 24 (5):  533-533.  Abstract ( 2175 )   [Full Text(HTML)] () PDF (75KB) ( 554 )

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Determination of Three Endogenous Hormones in Catharanthus roseus D. Using Solid-phase Extraction and High Performance Liquid Chromatography ZHAO Xiaoju, TANG Zhonghua, GUO Xiaorui, ZU Yuangang， JIAO Yan,SUN Yanfei, YANG Lei 2006, 24 (5):  534-534.  Abstract ( 2242 )   [Full Text(HTML)] () PDF (100KB) ( 627 )

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Determination of 1, 4-butanedisulphonate by Ion Exchange Chromatography with Suppressed Conductimetric Detection FAN Hui, DING Mingyu 2006, 24 (5):  535-536.  Abstract ( 2055 )   [Full Text(HTML)] () PDF (184KB) ( 677 )