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Chinese Journal of Chromatography
2006, Vol. 24, No. 2
Online: 30 March 2006

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Study on Gender Difference Based on Metabolites in Urine by Ultra High Performance Liquid Chromatography/ Time of Flight Mass Spectrometry LU Guo, WANG Jiangshan, ZHAO Xinjie, KONG Hongwei, XU Guowang 2006, 24 (2):  109-113.  Abstract ( 2486 )   [Full Text(HTML)] () PDF (622KB) ( 920 )   Metabolites in urine can illustrate the physical condition of an individual as a whole. Ultra high performance liquid chromatography/time of flight mass spectrometry (UPLC/TOF-MS) is a relative new technique for the separation of complex samples. The aim of this study is to assess the feasibility of metabonomics in gender difference in unrestricted conditions, i.e. for healthy volunteers there are no strict controls such as food, life style and the collection of urine samples. In this work, 31 spontaneous urine samples were collected and analyzed by using UPLC/TOF-MS. Principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA) models were tested and compared in samples classification. The gender discrimination was highly improved and some gender related biomarkers were found by PLS-DA. These preliminary results suggested that UPLC/MS-based approaches coupled with pattern recognition show promise for metabonomics.

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Preparation of A Novel Chiral Stationary Phase Based on Library of Small Peptides Obtained by Digestion of Bovine Serum Albumin with Trypsin LI Shengjing, YU Xin, ZHENG Jing, WANG Jinghui, XIAO Yuxiu 2006, 24 (2):  114-116.  Abstract ( 2721 )   [Full Text(HTML)] () PDF (222KB) ( 679 )   A novel chiral stationary phase (CSP) based on library of small peptides for high performance liquid chromatography (HPLC) is described. The conditions for digestion of bovine serum albumin (BSA) with trypsin were optimized, and the results of which were: enzymolysis time 6 h, enzymolysis pH 8.2, enzymolysis temperature 37 ℃. The obtained library of small peptides, which held many chiral recognition sites, could enhance the interaction between enantiomers and CSP. Then it was ultrafiltrated with membrane (Mr=6000) to discard Mr＞6000 molecules, and was bonded to aminopropyl-silica gel activated with 1,1′-carbonyldiimidazole. The proposed CSP held higher density of peptides’ ligand and was more steady than intact BSA-CSP. D,L-Tryptophan and D,L-tyrosine were well chiral separated on the novel peptides-CSP. The resolution (Rs) for D,L-tryptophan reached 10.48 with gradient pH buffer from 4.0 to 7.5. The Rs for D,L-tyrosine reached 13.50 with gradient pH buffer from 5.6 to 6.3. In the enantioseparation procedure of D,L-tryptophan and D,L-tyrosine, pH gradient elution was applied. The results could be ascribable to that the variation in pH of mobile phase can change dissociation of both enantiomers and peptides on CSP, which influenced the interaction between them by the conformation of peptides and/or the electrostatic situation and the hydrophobicity of solutes.

Articles

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Study of Blending Method for the Extracts of Herbal Plants LIU Yongsuo, CAO Min, CHEN Yuying, HU Yuzhu, WANG Yiming, LUO Guoan 2006, 24 (2):  117-121.  Abstract ( 2179 )   [Full Text(HTML)] () PDF (219KB) ( 696 )   The irregularity in herbal plant composition is influenced by multiple factors. As for quality control of traditional Chinese medicine, the most critical challenge is to ensure the dosage content uniformity. This content uniformity can be improved by blending different batches of the extracts of herbal plants. Nonlinear least-squares regression was used to calculate the blending coefficient, which means no great absolute differences allowed for all ingredients. For traditional Chinese medicines, even relatively smaller differences could present to be very important for all the ingredients. The auto-scaling pretreatment was used prior to the calculation of the blending coefficients. The pretreatment buffered the characteristics of individual data for the ingredients in different batches, so an improved auto-scaling pretreatment method was proposed. With the improved auto-scaling pretreatment, the relative differences decreased after blending different batches of extracts of herbal plants according to the reference samples. And the content uniformity control of the specific ingredients could be achieved by the error control coefficient. In the studies for the extracts of fructus gardeniae, the relative differences of all the ingredients is less than 3% after blending different batches of the extracts. The results showed that nonlinear least-squares regression can be used to calculate the blending coefficient of the herbal plant extracts.

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Application of Adjustable Moving Overlapping Separation Range Map in Multisegment Stepwise Gradient Elution Condition Optimization of High Performance Liquid Chromatography SHAN Yichu, ZHANG Weibing, SEIDEL-MORGENSTERN Andreas, ZHAO Ruihuan, ZHANG Yukui 2006, 24 (2):  122-128.  Abstract ( 2165 )   [Full Text(HTML)] () PDF (8128KB) ( 594 )   Computer-assisted optimization of high performance liquid chromatographic separation conditions can be used to obtain optimized experimental conditions in relatively short time and low cost, and has been widely applied to the separation of complex samples. Based on “moving overlapping separation range map” method, a novel method of optimizing multi-segment stepwise gradient elution conditions, “adjustable moving overlapping separation range map” method, was developed. By predicting the retention time, peak width and resolution of each solute under different mobile phase conditions, the overlapping separation range map of the solutes in the sample is plotted. When the mobile phase composition on the current step is optimized, the overlapping separation range map for solutes eluted in next one or two steps is replotted simultaneously by considering the influence of elution conditions for current step on the retention of uneluted solutes. It is helpful to consider the separation of each solute in the sample simultaneously and find optimized separation conditions close to the global optimum by investigating the effect of mobile phase conditions for current step on the separation of solutes eluted in the current and next one or two steps. By slightly adjusting the optimized separation conditions using grid search method, the separation performance can be further improved. The application of “adjustable moving overlapping separation range map” method was illustrated by using experimental data from literature. The advantage of this method in high performance liquid chromatography was verified in binary mobile phase system.

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Preparation of Strong Cation Exchange Packings Based on Monodisperse Hydrophilic Non-Porous Resins and Their Application for Fast Separation of Proteins ZHU Jinxia, BO Chunmiao, GONG Bolin, 2006, 24 (2):  129-134.  Abstract ( 2607 )   [Full Text(HTML)] () PDF (2979KB) ( 1114 )   Monodisperse, 3.0 μm non-porous hydrophilic poly (glycidylmethacrylate-co-ethylenedimethacrylate) particles were prepared by an one-step swelling and polymerization method. The particles were modified to be a strong cation exchange (SCX) stationary phase for high performance liquid chromatography (HPLC) in the following steps. First, the particles were completely hydrolyzed. Second, the hydrolyzed particles were treated with epichlorhydrin followed by another hydrolysis of the newly introduced epoxide groups. Third, the particles were reacted with chlorosulfonic acid. The SCX stationary phase was evaluated in light of the ion exchange property, separability and hydrophilicity on the separation and retention of proteins in detail. Four proteins were quickly separated in 1.0 min with linear gradient elution using the synthesized SCX stationary phase. It was found that it followed ion exchange chromatographic (IEC) retention mechanism. The SCX resin was used for the fast purification of lysozyme from egg white and cytochrome-C from pig heart in 3.0 min with only one step. The results obtained were satisfactory.

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Three-Step Column Chromatographic Method for Separation and Purification of Thrombin-Like Enzyme from Venom of Agkistrodon halys pallas BIAN Liujiao, YANG Xiaoyan, LIU Li 2006, 24 (2):  135-139.  Abstract ( 2403 )   [Full Text(HTML)] () PDF (511KB) ( 681 )   A three-step column chromatographic method, utilizing CM Sepharose CL-6B, DEAE Sepharose Fast Flow and Sephadex G-75 in sequence, for the separation and purification of thrombin-like enzyme from crude venom of Agkistrodon halys pallas was developed. Based on the separation results on lab-scale chromatographic column, this isolation and purification process was amplified according to the diameter of the chromatographic columns used in lab-scale. It was found that when the amount of the sample loaded on the large-scale columns was 25 times as that loaded on the lab-scale columns, the quality level of the thrombin-like enzyme obtained with the large-scale columns was almost the same as that obtained with lab-scale columns. The relative molecular mass of thrombin-like enzyme obtained was about 33500, and its purity was about 96%. When using this method to isolate thrombin-like enzyme from crude venom of Agkistrodon halys pallas, the total protein yield and total activity yield of thrombin-like enzyme were about 0.3% and 64% respectively, and specific activity was more than 2000 U/mg.

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Simultaneous Determination of Kynurenine and Tryptophan in Serum by High Performance Liquid Chromatography WANG Rui, TANG Aiguo 2006, 24 (2):  140-143.  Abstract ( 2172 )   [Full Text(HTML)] () PDF (325KB) ( 1051 )   A method was established for the simultaneous determination of kynurenine (Kyn) and tryptophan (Trp) in serum by high performance liquid chromatography-ultraviolet detection (HPLC-UV). It employed a Symmetry Shield RP-C18 column (150 mm×3.9 mm i.d., 5 μm) and a mobile phase of 15 mmol/L sodium acetate-acetic acid solution containing 2.7% (v/v) acetonitrile (pH 3.6) at a flow rate of 1.0 mL/min. The ultraviolet detector was operated at 225 nm. Serum samples were first precipitated with a 5.0% perchloric acid solution, then centrifuged to remove protein residue and finally analyzed by HPLC. The retention time of Kyn was 3.5 min, the linear range of the method was from 0.098 to 49　μmol/L, and the detection limit was 0.02 μmol/L. The recoveries of Kyn were from 90.82% to 93.45%, the intraday and interday variations were 2.37% and 3.66%, respectively. The retention time of Trp was 8.1 min, the linear range of the method was from 4.9 to 490 μmol/L, and the detection limit was 0.20 μmol/L. The recoveries of Trp were from 95.51% to 98.67%, the intraday and interday variations were 1.50% and 2.65%, respectively. The method is simple, fast, accurate, and suitable for routine analysis.

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Separation of Enantiomers of Amino Acid Derivatives by High Performance Liquid Chromatography on Teicoplanin　Chiral Stationary Phase LIN Lin, XIA Lijun, XU Xu, XU Hongyan, 2006, 24 (2):  144-147.  Abstract ( 2317 )   [Full Text(HTML)] () PDF (382KB) ( 780 )   Direct enantioseparations of seven N-fluorenylmethoxycarbonyl-amino acids (Fmoc-Val, Fmoc-Ser, Fmoc-Leu, Fmoc-Ile, Fmoc-Met, Fmoc-Ala, and Fmoc-Phe) were achieved by high performance liquid chromatography using a 250 mm×4.6 mm i.d. column bonded teicoplanin on silica gel as chiral stationary phase and methanol-acetic acid-triethylamine mixtures as mobile phase. The comparison of retention behavior and enantioseparation of N-Fmoc-Val and its non-blocked analogue on a Chirobiotic column with different mobile phase systems is presented. The effects of the content of acetic acid and triethylamine and the content ratio of acetic acid and triethylamine in the mobile phase on the enantioseparation of some N-Fmoc-amino acids were examined. The results showed that variations of column temperature and flow rate of mobile phase also had effects on enantioseparation of N-Fmoc-amino acids. The method had been successfully applied to the determination of optical purity of some derivatized amino acids.

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Determination of Dihydroxybenzenes Using High Performance Liquid Chromatography with Acidic Potassium Permanganate Chemiluminescence FAN Shunli, ZHANG Like, WEI Yanlin, LIN Jin-Ming 2006, 24 (2):  148-151.  Abstract ( 2290 )   [Full Text(HTML)] () PDF (458KB) ( 788 )   A sensitive, selective and simple post-column chemiluminescence (CL) detection method for simultaneously determining catechol, resorcinol, hydroquinone has been developed based on high performance liquid chromatography (HPLC) coupled with CL detection using reaction of dihydroxybenzenes with acidified potassium permanganate solution with the enhancing effect of formic acid. The optimal conditions for the CL detection and HPLC separation were achieved. Dihydroxybenzene isomers were baseline separated at column temperature of 25 ℃ using a mobile phase of methanol-0.1 mmol/L β-cyclodextrin aqueous solution (30/70, v/v) with an isocratic elution program and the mobile phase matched well the CL detection. For all compounds, the linear ranges of the CL detection were about two orders of magnitude. The detection limits were 3.2 μg/L for hydroquinone, 4.7 μg/L for resorcinol and 5.2 μg/L for catechol. Combining with solid phase extraction, the proposed method was successfully applied to the determination of dihydroxybenzenes in river water. The recoveries for the three dihydroxybenzenes were 92.1%-95.4%.

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Simultaneous Determination of Twelve Sulfonyl Urea Herbicide Residues in Rice by High Performance Liquid Chromatography with Solid-Phase Extraction SUI Kai, LI Jun, WEI Feng, CHU Xiaogang, ZHAO Shoucheng, WANG Yuping 2006, 24 (2):  152-156.  Abstract ( 2315 )   [Full Text(HTML)] () PDF (639KB) ( 892 )   A high performance liquid chromatographic (HPLC) method with solid-phase extraction was developed for screening of 12 sulfonyl urea herbicides in rice. The sample was cleaned up and extracted with ENVITM-18 （C18） and ENVI-Carb （GCB） columns. The separation was performed on a SymmetryshieldTM RP8 column （4.6 mm i.d.×150 mm）with a linear gradient elution (acetonitrile and 5 mmol/L acetic acid as mobile phase), and the wavelength of an ultraviolet detector was set to 240 nm for the detection. The linear range was 0.1-10 mg/L, and the correlation coefficients were 0.9983-0.9999. Recoveries from rice samples spiked with 12 sulfonyl urea herbicides at spiking levels ranging from 0.01-0.50 μg/g were from 72.2% to 106.5%, with relative standard deviations from 0.6% to 6.4%. The lowest detection limits (S/N=3) were 0.01-0.02 μg/g. The results indicate that the method is easier, faster, sensitive and has better purification effect. It also demonstrates that this multiresidue analytical method can meet the requirements for simultaneous determination of sulfonylurea herbicides in rice.

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Determination of Bitter Components in Citrus Juice by High Performance Liquid Chromatography CHEN Jing, GAO Yanxiang, WU Weili, LI Shaozhen 2006, 24 (2):  157-160.  Abstract ( 2078 )   [Full Text(HTML)] () PDF (296KB) ( 958 )   Bitterness in citrus juice is primarily due to the presence of both limonin and naringin, and determination of them is a standard in controlling the quality of juice. A high performance liquid chromatographic （HPLC） method was developed for the rapid determination of bitter components in citrus juice. The HPLC conditions were as follows: ODS column with acetonitrile-tetrahydrofuran-water (17.5∶17.5∶65, v/v) as mobile phase, flow rate at 1 mL/min, 207 nm as detection wavelength for limonin, and methanol-100% acetic acid-water (40∶1∶59, v/v) as mobile phase, flow rate at 1 mL /min, 283 nm as detection wavelength for naringin. As results showed, for limonin and naringin, the linearity was good within the ranges of 1.00-50.00 mg/L (r=0.9992) and 20.00-160.00 mg/L (r= 0.9988) respectively, and the detection limits were 0.07 μg and 0.14 μg, then the average recoveries were 98.69% and 100.13% with relative standard deviations of 2.5% and 1.5% , respectively. The method is simple, rapid and accurate for determining limonin and naringin in juice.

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Determination of Carotenoids in Flue-Cured Tobacco Leaves During its Growth by Reversed-Phase High Performance Liquid Chromatography LIU Guoshun, WEI Fengjie, WANG Fang, LI Yajuan, GUO Qiaoyan, HUANG Xiaoshu 2006, 24 (2):  161-163.  Abstract ( 1999 )   [Full Text(HTML)] () PDF (313KB) ( 901 )   A reversed-phase high performance liquid chromatographic (RP-HPLC) method for the determination of carotenoids in flue-cured tobacco leaves was developed. Carotenoids were extracted from flue-cured tobacco leaves by acetone-water (90∶10, v/v) solution containing 0.1% butylated hydroxytoluene (BHT). Plant proteins were eliminated by adding 0.1 g Pb(Ac)2 and by centrifugation (10000 r/min) for 5 min at 4 ℃. Lutein, β-carotene, neoxanthin, violaxanthin and other plant pigments were separated on a reversed-phase C18 column (3.9 mm i.d.×150 mm, 5 μm), with a mobile phase of (A) methanol-isopropyl alcohol (1∶1, v/v) and (B) water using a gradient elution at a flow rate of 0.5 mL/min. The optimum elution gradient was as follows: 0-10 min, 70%A+30%B; 10-17 min, 100%A; 17-30 min, 90%A＋10%B. The recoveries of carotenoids in flue-cured tobacco leaves were 91.77%-97.42%, and relative standard deviations were 3.46%-0.98%. This method was applied to determine carotenoids in flue-cured tobacco leaves during its growth with satisfactory results.

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Determination of Contents and Dissolution of Ethambutol Hydrochloride in Fixed Dose Combinations for Anti-Tuberculosis Drugs by High Performance Liquid Chromatography with Pre-Column Derivatization SUN Jin, SONG Hongtao, ZHANG Tianhong, WANG Zhuo, HE Zhonggui 2006, 24 (2):  164-167.  Abstract ( 2184 )   [Full Text(HTML)] () PDF (294KB) ( 957 )   A reversed-phase high performance liquid chromatographic method (RP-HPLC) with pre-column derivatization and ultraviolet (UV) detection was established to determine ethambutol hydrochloride in fixed dose combinations (FDCs) for anti-tuberculosis drugs. The derivatization was carried out in a non-aqueous environment, where ethambutol hydrochloride was derivatized with phenylethylisocyanate at an optimal molar ratio of 1∶6. The extraction recovery was 98.7% with the mean relative standard deviation of 0.70%. The accuracy and precision of the method were all qualified. The linear regression of the standard calibration curve was determined and the linearity was good (r=0.9993). The method is sensitive, specific, rapid, and can be successfully applied to the quantitation and dissolution of ethambutol hydrochloride in FDCs.

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Study on Content Variation of Chemical Constituents During Combination of Rhizoma Coptidis Alkaloids with Fructus Evodiae Flavonoids by High Performance Liquid Chromatography PAN Langsheng, LU Xiuyang, XU Haidan, WU Pingdong 2006, 24 (2):  168-170.  Abstract ( 2108 )   [Full Text(HTML)] () PDF (212KB) ( 736 )   In order to study the compatibility of Chinese herbal drugs, a method was proposed by investigating chemical reactions with combination of chemical constituents or major groups of chemical compounds of Chinese herbal drugs. The content variation of chemical constituents during combination of rhizoma coptidis alkaloids with fructus evodiae flavonoids was analyzed by high performance liquid chromatography (HPLC). The experimental results showed that only small changes of the relative peak areas of different chemical constituents were observed and no new peaks were detected. No chemical reactions were observed during the compatibility test of rhizoma coptidis alkaloids with fructus evodiae flavonoids.

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Determination of Tetracycline Antibiotics Residues in Chicken Muscle by Liquid Chromatography-Tandem Mass Spectrometry LIU Yanhua, ZHANG Chunping, MEN Liqiang, LIU Zhihong, WANG Shuhuai 2006, 24 (2):  171-173.  Abstract ( 2146 )   [Full Text(HTML)] () PDF (292KB) ( 1226 )   A sensitive and selective method is presented for simultaneous determination of tetracycline antibiotics (TCs) veterinary drugs. Oxytetracycline (OTC), tetracyclines (TC) and chlortetracycline (CTC) in the chicken muscle were extracted, and then solid-phase cleaned-up on a C18 reversed-phase column to obtain an extract suitable for analysis by liquid chromatography-tandem mass spectrometry（LC-MS/MS）. Electrospray ionization was applied and operated in the positive ion mode. The calibration curves were good linear between the peak areas and the mass concentrations of TCs from 25 to 500 μg/L with the correlation coefficient more than 0.99. The average recoveries from spiked chicken muscle at the three concentrations of 50, 100 and 200 μg/kg were from 72.4% to 94.9% with relative standard deviation less than 11%. The detection limits of TCs were 10 μg/kg. The method was successfully validated for chicken muscle in compliance with the requirements set by Document No.1 of 2003 dispatched by the Bureau of Animal Husbandary of Ministry of Agriculture. This method is suitable for the determination of OTC,TC and CTC in chicken muscle.

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Determination of Organophosphorus Pesticide Residues in Tobacco by High Performance Liquid Chromatography- Tandem Mass Spectrometry LIU Yingwen, DING Shichao, DU Wen, YIN Donghong, LIU Jianfu 2006, 24 (2):  174-176.  Abstract ( 2359 )   [Full Text(HTML)] () PDF (246KB) ( 1266 )   A novel and rapid method based on high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for determination of organophosphorus pesticide residues (OPs) in tobacco. The OPs were extracted from tobacco samples by acetonitrile under ultrasonication. The extractive was determined by high performance liquid chromatography using methanol-water (containing 0.1% ammonium acetate) (95∶5, v/v) as mobile phase. The OPs were detected using a tandem mass spectrometer with electrospray ionization in multiple reaction monitoring (MRM) mode. The OPs, such as dimethoate, trichlorfon, chlorpyrifos, methamidophos and acephate could be detected quantitatively within 2.5 min. The linear calibration curves were obtained in the entire range (1-200 μg/L) for all the above pesticides (r＞0.998). The average recoveries in tobacco obtained were ranged from 77% to 104%. The limits of detection were between 1.0 μg/kg and 5.0 μg/kg.

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Separation and Identification of Volatile Flavors of Jinhua Ham by Gas Chromatography-Mass Spectrometry Coupled with Head Space Solid Phase Microextraction TIAN Huaixiang, WANG Zhang, XU Shiying 2006, 24 (2):  177-180.  Abstract ( 2010 )   [Full Text(HTML)] () PDF (281KB) ( 1782 )   Head space solid phase microextraction (SPME) technique was employed to extract volatile flavor compounds from the Chinese traditional food, Jinhua ham. Volatile flavor components of Jinhua ham were isolated and identified successfully by capillary gas chromatography-mass spectrometry (GC-MS). A 75 μm carboxen/poly(dimethysiloxane) （CAR-PDMS） fiber was selected to be the optimum fiber among four different fibers. Optimum adsorption time was 40 min at 60 ℃. Aldehydes, carboxylic acids and acetones were the major flavor compounds of Jinhua ham.

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Analysis of Fatty Acids in Gymnocypris przewalskii Oil by Gas Chromatography/Mass Spectrometry with Base-Catalyzed Transesterification BO Haibo, WANG Xia, ZHAI Zongde, LI Yongmin, CHEN Liren 2006, 24 (2):  181-184.  Abstract ( 2333 )   [Full Text(HTML)] () PDF (282KB) ( 791 )   The composition of fatty acids (FA) in Gymnocypris przewalskii oil was identified and quantified by gas chromatography (GC)/electron impact (EI) mass spectrometry (MS). A base-catalyzed transesterification method was used to convert fatty acids to methyl esters. The lipids were extracted using petroleum ether and the total lipids in dried meat and skin of Gymnocypris przewalskii were about 25%. Forty-seven fatty acids were identified in the current study. Main types of fatty acids found in the oils were normal saturated, mono-branched, multi-branched, cyclopropane, furanoid, normal monounsaturated and polyunsaturated fatty acids. Saturated fatty acids were approximately 25.7% of the total, and the main components were C14∶0(3.4%), C16∶0 (19.4%) and C18∶0(1.1%). Unsaturated fatty acids were totally 73.6%, and the major components of monounsaturated fatty acids were C16∶1 (9) (19.8%), C18∶1 (9) (18.6%) and C18∶1 (11) (7.3%); polyunsaturated fatty acids were mainly composed of C18∶2 (9,12) (4.8%), C18∶3 (9,12,15) (3.1%), C20∶4 (5,8,11,14) (1.2%), C20∶5 (5,8,11,14,17) (EPA, 9.4%) and C22∶6 (4,7,10,13,16,19) (DHA, 6.7%). Especially, furyl-, cyclopropane- and several odd and branched chain fatty acids were found in Gymnocypris przewalskii oil. It is thus an important dietary resource of functional fatty acids.

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Analysis of Volatile Constituents in Leaves of Three Cypress Species by Gas Chromatography/Mass Spectrometry HAO Dejun, ZHANG Yonghui, DAI Huaguo, WANG Yan 2006, 24 (2):  185-187.  Abstract ( 2385 )   [Full Text(HTML)] () PDF (155KB) ( 934 )   Volatile oils in leaves of three cypress species were extracted by hydrodistillation method and analyzed by gas chromatography/mass spectrometry. Sixty-four constituents were separated and identified. The majority of the components were found to be monoterpenes and sesquiterpenes. There were 33, 37, 37 compounds in the oils of leaves of Sabina chinensis (L.) Ant, Cupressus lusitanica ‘zhongshan’ Mill and Sabina chinensis (L.) Ant. Cv. Kaizuca, respectively. Fourteen compounds were common to them, which were thujene, α-pinene, camphene, sabinene, β-myrcene, α-terpinene, γ-terpinene, α-terpinolene, bornyl acetate, β-elemene, α-amorphene, germacrene D, δ-cadinene and elemol. In addition, each species had particular compounds. The main components were found to be: sabinene (20.99%), limonene (19.78%) and bornyl acetate (11.68%) for Sabina chinensis (L.) Ant; α-pinene (10.39%), sabinene (11.19%) and δ-3-carene (8.88%) for Cupressus lusitanica ‘zhongshan’ Mill; limonene (24.56%), β-myrcene (8.04%) for Sabina chinensis (L.) Ant. Cv. Kaizuca.

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Chiral Separation of Dipeptides by Capillary Electrophoresis CHENG Yan, BAI Min, WANG Xinmei, MING Yongfei, YOU Jinmao 2006, 24 (2):  188-191.  Abstract ( 2509 )   [Full Text(HTML)] () PDF (513KB) ( 658 )   Peptides are increasingly used as pharmaceutical agents. Many small peptides are the essential compounds in biological systems. Direct chiral separation of dipeptide derivatives using 9-(2-carbazole) ethyl chloroformate (CEOC) as the derivatizing agent by capillary electrophoresis (CE) with β-cyclodextrin (β-CD) and sodium deoxycholate (SDC) as chiral selectors has been developed. It has been well recognized that the combination of the binary selectors can enhance the selectivity and resolution instead of either β-CD or SDC alone. The molar ratio of the binary chiral selectors, the buffer concentration and pH of Tris-H3PO4, organic modifier were studied and optimized. Complete chiral separations for 14 dipeptide derivatives using β-CD and SDC as binary chiral selectors were obtained. The results indicated that each pair of D/L chiral resolution was more than 3.63, and the highest resolution for Gly-Ala was 43.14.

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Study on Elimination of 3-Chloro-1,2-Propanediol in Hydrolyzed Vegetable Protein by Capillary Electrophoresis with Electrochemical Detection XING Xiaoping, CAO Yuhua 2006, 24 (2):  192-195.  Abstract ( 2158 )   [Full Text(HTML)] () PDF (397KB) ( 784 )   A method was developed to estimate 3-chloro-1,2-propanediol (3-MCPD) in hydrolyzed vegetable protein (HVP) by capillary electrophoresis with electrochemical detection. The optimum conditions were investigated to determine 3-MCPD in hydrolyzed vegetable protein. In 30 mmol/L borax (pH 9.24) running buffer, separation of 3-MCPD from glycerol was achieved. A 328 μm copper-disk electrode used as the working electrode exhibited a good response at +0.65 V (vs. saturated calomel electrode (SCE)) in 0.05 mol/L sodium hydroxide solution. The effects of pH value, temperature and hydrolysis time on the elimination of 3-MCPD in hydrolyzed vegetable protein were studied. By adjusting hydrolyzed vegetable protein to pH value of 8.0 and heating up for 1 h at 90 ℃, the content of 3-MCPD in hydrolyzed vegetable protein could be controlled under the level of 1.0 mg/kg, which coincides with the criterion of food safety in China.

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Study on the Fingerprints of Fructus Forsythiae by High Performance Capillary Electrophoresis SUN Guoxiang, MU Shanxue, HOU Zhifei, SUN Yuqing 2006, 24 (2):  196-200.  Abstract ( 2192 )   [Full Text(HTML)] () PDF (658KB) ( 852 )   The capillary electrophoresis fingerprints (CEFP) of Fructus Forsythiae was established to control its quality. The background electrolyte (BGE) was a 75 mmol/L sodium borate solution adjusted to pH 9.7 with 0.1 mmol/L NaOH solution. The detection wavelength was 228 nm and a voltage of 14 kV was applied. The Forsythia suspensa (Thunb.) Vahl was extracted by water and a set of CEFP containing 29 peaks was obtained. The CEFP had acceptable precision and reproducibility with the relative standard deviation (RSD) of the relative migration time less than 5.0% and the RSD of the relative peak area from 2% to 15%. There were good similarities between the standard CEFP and each set of CEFP of Forsythia suspensa (Thunb.) Vahl from ten different places, and their similarity coefficients were not less than 0.94. The CEFP were also evaluated by the information index I and the relative information index Ir of chromatographic fingerprint.

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Determination of Water-Soluble Glucose, Fructose and Sucrose in Flue-Cured Tobacco by High Performance Anion Exchange Chromatography Coupled with Pulsed Amperometric Detection WANG Li, CHEN Qiaozhen, SONG Guoxin, SHEN Yi, LIU Baizhan 2006, 24 (2):  201-204.  Abstract ( 2498 )   [Full Text(HTML)] () PDF (493KB) ( 926 )   The quantitative determination of water-soluble sugars such as glucose, fructose and sucrose in flue-cured tobacco by high performance anion exchange chromatography coupled with pulsed amperometric detection （HPAEC-PAD） was developed. The method was used to determine flue-cured tobacco samples containing large amounts of carbohydrates after pretreatment by water-leaching and membrane filtration. The separation was performed on a Dionex CarboPac PA-1 anion exchange column with 0.2 mol/L NaOH solution as the eluent at a flow rate of 1.0 mL/min. The injection volume was 20 μL. Good linearities were obtained for glucose, fructose and sucrose within the range of 0.5-100 mg/L (r2＞0.997). The detection limits (S/N= 3) were 0.1 mg/L, 0.1 mg/L and 0.2 mg/L, and the average recoveries were 97.3%, 101.4% and 98.9% with good reproducibility for glucose, fructose and sucrose, respectively.