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Chinese Journal of Chromatography
2014, Vol. 32, No. 8
Online: 08 August 2014

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Preparation and evaluation of pepsin affinity organic polymer capillary monolithic column CHI Cuijie, WANG Wei, JI Yibing 2014, 32 (8):  791-797.  DOI: 10.3724/SP.J.1123.2014.04042 Abstract ( 816 )   [Full Text(HTML)] () PDF (6556KB) ( 209 )   The protein modified monolithic column in affinity capillary electrochromatography (CEC) has attracted considerable attention over the past decades because of its great enantioseparation ability. A porous polymethacrylate ester-based capillary monolithic column poly (glycidyl methacrylate-co-ethyleneglycol dimethacrylate) (poly(GMA-co-EDMA)) was prepared by in situ co-polymerization. The process was initiated thermally by azobisisobutyronitrile (AIBN). The polymerization mixture contained GMA as the function monomer and EDMA as the crosslinking agent with 1,4-butanediol and 1-propanol as the binary porogen solvent. Under the optimized reaction conditions, including the proportion of monomer and porogens, reaction temperature etc, the column exhibited a uniform structure, sufficient permeability and excellent pressure resistance. The separation of alkyl benzenes on the column was mainly based on typical reversed-phase chromatographic retention mechanism. The reproducibility and stability were good with RSDs less than 9.0%. A pepsin functionalized organic polymer monolith was prepared by covalently bonded pepsin to poly(GMA-co-EDMA) monolith with glutaraldehyde as a spacer based on the activity of epoxide group. The enantioseparation performance of the pepsin affinity monolith for basic enantiomers has been investigated by CEC. Nefopam, amlodipine, citalopram and chlorpheniramine were resolved, and baseline separations of nefopam, amlodipine, citalopram were achieved. The influences of pH, operating voltage, temperature and sample quantity used on the chiral separation were studied. The chiral recognition mechanism of enantiomers on the monolithic column in CEC is discussed. This work developed a new method for the preparation and application of protein affinity monolith in CEC.

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Preparation and application of an emodin-bonded silica gel chromatographic column for high performance liquid chromatography XU Lili, REN Nailin, LIN Zeling 2014, 32 (8):  798-803.  DOI: 10.3724/SP.J.1123.2014.04038 Abstract ( 887 )   [Full Text(HTML)] () PDF (832KB) ( 264 )   An emodin-bonded silica gel stationary phase (ESP) for high performance liquid chromatography has been synthesized by the intermediate method. The preparation process was as follows:γ-glycidoxypropyltrimethoxy silane (KH-560) firstly reacted with emodin ligand; then the intermediate was chemically immobilized to the surface of silica gel. Characterization of ESP was carried out with Fourier transform infrared spectroscopy (FTIR), elemental analysis and thermogravimetric analysis. Naphthalene was used as a probe to determine the column efficiency with methanol-water (60:40, v/v) as binary mobile phase at a flow rate of 0.8 mL/min. In order to elucidate the related separation mechanism, ESP was used to separate a series of neutral, basic and acidic aromatic compounds, as well as a sample of wind medicated oil. The conventional C18 column and phenyl column were also tested under the same chromatographic conditions for comparison. The results showed that the emodin ligand was successfully bonded to the surface of spherical silica gel with a 0.23 mmol/g of bonded amount, and the theoretical plate number of ESP column was about 19874 N/m. The coupling reagent chains and anthraquinone rings in ESP offered a structural basis for hydrophobic interaction. Meanwhile, the emodin ligands provided π-π or p-π, charge transfer, hydrogen bonding, dipole-dipole action sites for different analytes. The synergistic reaction of various action sites endowed ESP column special and excellent chromatographic separation selectivity. And a baseline separation of polar compounds such as amines and phenols on ESP was easily achieved by using common and cheap methanol-water mobile phases without buffer salts. The experimental conditions were simple and convenient.

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Non-targeted metabolomics study for the analysis of chemical compositions in three types of tea by using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry ZHANG Lei, ZENG Zhongda, YE Guozhu, ZHAO Chunxia, LU Xin, XU Guowang 2014, 32 (8):  804-816.  DOI: 10.3724/SP.J.1123.2014.04029 Abstract ( 1088 )   [Full Text(HTML)] () PDF (3284KB) ( 551 )   Tea is one of the most widely consumed beverages in the world for its benefits to daily life and health. To discover the difference and correlation of chemical compositions in the three typical types of tea, a non-targeted metabolomics method was developed. After the optimization of extraction methods, gas chromatography-time-of-flight mass spectrometry and liquid chromatography-quadrupole time-of-flight mass spectrometry were applied for metabolomics analysis, 1812 and 2608 features were obtained, respectively. By comparing with the known compounds in public and/or commercial databases, 173 compounds were tentatively identified, and 109 of them were experimentally confirmed by standards. Totally, 33 tea samples including 12, 12 and 9 samples of green, oolong and black tea, respectively, were analyzed by using the above two methods. Multivariate analysis, Mann-Whitney U test and hierarchical cluster analysis were used to find and visualize the differential components in the three types of tea. Finally, 90 compounds, which contain catechins, amino acids, organic acids, flavonol glycosides, alkaloids, carbohydrates, lipids, etc, were found with a significant difference among them. This study demonstrates the potentials and power of metabolomics methods to understand the chemical secrets of tea. This should help a lot to optimize the processes of agriculture, storage, preparation and consumption.

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Determination of tetrabromobisphenol A and bisphenol A in environmental water using carboxylated multiwalled carbon nanotubes as sorbent for solid-phase extraction combined with liquid chromatography-tandem mass spectrometry KOU Lijuan, LIANG Rongning 2014, 32 (8):  817-821.  DOI: 10.3724/SP.J.1123.2014.03045 Abstract ( 732 )   [Full Text(HTML)] () PDF (800KB) ( 286 )   A method for the determination of tetrabromobisphenol A and bisphenol A in environmental water using carboxyl-functionalized multiwalled carbon nanotubes as solid-phase extraction sorbent and liquid chromatography-tandem mass spectrometry was established. Comparison of three nanomaterials including multiwalled carbon nanotubes, C60 and carboxyl-functionalized multiwalled carbon nanotubes used as solid-phase extraction sorbents was made. After preconcentration by solid-phase extraction, tetrabromobisphenol A and bisphenol A were separated on a Thermo Scientific Hypersil C18 column (150 mm×4.6 mm, 3 μm) and then detected by tandem mass spectrometry in negative electrospray ionization (ESI) mode. The results showed a good linear response in the concentration range of 0.02-1.0 mg/L for tetrabromobisphenol A and bisphenol A, and the limits of detection (S/N=3) were 0.04 μg/L and 0.2 μg/L for tetrabromobisphenol A and bisphenol A, respectively. The application of the proposed approach has been carried out for the determination of tetrabromobisphenol A and bisphenol A in spiked lake water and sea water samples. The recoveries varied from 82% to 99% with the relative standard deviations below 5.0%. The proposed method can be used for the determination of tetrabromobisphenol A and bisphenol A at trace level in complex environmental samples.

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Simultaneous determination of nine antidepressants in traditional Chinese medicines and health food by ultra performance liquid chromatography with tandem mass spectrometry GOU Xinlei, GAO Xia, HU Guanghui, LIU Weili 2014, 32 (8):  822-826.  DOI: 10.3724/SP.J.1123.2014.03032 Abstract ( 625 )   [Full Text(HTML)] () PDF (971KB) ( 337 )   A sensitive method was developed for the simultaneous determination of nine antidepressants in traditional Chinese medicines and health food by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) based on the sonication-assisted extraction. The separation was performed on a Waters ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm) by using 0.1% (v/v) formic acid aqueous solution and acetonitrile as the mobile phases with gradient elution at a flow rate of 0.2 mL/min. The electrospray ionization (ESI) source in positive ion mode was used for the analysis of the nine antidepressants in the multiple reaction monitoring (MRM) mode. The standard curves for the nine antidepressants were obtained with good correlation coefficients (R2>0.998) in the concentration range of 0.04-20 μg/L. The limits of detection for the nine antidepressants were in the range of 0.0068-0.034 μg/L. The average recoveries at three spiked levels (0.5, 1, 5 μg/L) were 77.7%-100.8% with the relative standard deviation of 0.9%-9.1%. The method is accurate, simple, rapid and feasible for the simultaneous determination of the antidepressants in traditional Chinese medicines and health food.

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Simultaneous determination of eight additives in polymer food packaging materials by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry ZHANG Xulong, LIU Yin, GONG Zhiguo, WANG Pengju, WANG Jide, FENG Shun 2014, 32 (8):  827-831.  DOI: 10.3724/SP.J.1123.2014.05038 Abstract ( 759 )   [Full Text(HTML)] () PDF (788KB) ( 261 )   An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was proposed for the simultaneous determination of eight additives (Irgafos 168 (tri(2.4-di-tert-butylphenyl)phosphite), Irganox 1076 (octadecyl-β-(4-hydroxy-3,5-di-tert-butyl- phenyl)propionate), Irganox 1010 (pentaerythritol tetrakys 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), BHA (butyl hydroxy anisole), TBHQ (tertiary butylhydroquinone), PG (propyl gallate), DG(dodecyl gallate), UV-326 (2-(2'-hydroxyl-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole) in food packaging materials. After extracted by chloromethane through ultrasonic extraction, the samples were analyzed by UPLC-MS/MS. The chromatographic conditions were optimized, and the best separation was obtained on a Waters BEH-C18 column (50 mm×2.1 mm, 1.7 μm) with gradient elution of 0.05% acetic acid solution and methanol. The analysis was performed by UPLC-MS/MS with electrospray ionization (ESI) source in switching between the positive and negative ion modes in one run for multiple reaction monitoring. The eight additives showed good linear relationships in the ranges with all the correlation coefficients (R2) more than 0.993. The limits of detection (LODs, S/N=3) and limits of quantitation (LOQs, S/N=10) of this method were 0.13-5.50 μg/L and 0.45-17.50 μg/L, respectively. The recoveries were in the range of 63.9%-127.0% with all the RSDs≤15.8% (n=6). This method is simple, accurate and effective for the analysis of the eight additives in food packaging materials.

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Chiral separation of six tetralone derivative enantiomers using immobilized cellulose chiral stationary phase ZHAO Yunfeng, SONG Jiaxin, SUN Jiayi, YUAN Xiaowei, GUO Xingjie 2014, 32 (8):  832-836.  DOI: 10.3724/SP.J.1123.2014.03035 Abstract ( 719 )   [Full Text(HTML)] () PDF (805KB) ( 238 )   A high performance liquid chromatographic method (HPLC) was developed for the chiral separation of six α -aryl tetralone derivatives using a Chiralpak IC column. The factors influencing the chiral separation including the type and concentration of organic modifier, column temperature and flow rate were investigated. The results showed that high enantiomeric separation can be obtained with isopropanol as modifier for the six compounds. The thermodynamic study indicated that the enantioseparation was enthalpically driven and showed that low column temperature was beneficial to separation. Complete separation of compound Ⅰ was achieved with a binary solvent mixture of n-hexane-isopropanol (90:10, v/v) as the recommended mobile phase. The compounds Ⅱ, Ⅲ and Ⅳ were separated with the mobile phase of the mixture of n-hexane-isopropanol (99:1, v/v) and the compound Ⅴ was separated with the mixture of n-hexane-isopropanol (85:15, v/v). The compound Ⅵ was separated with the mixture of n-hexane-isopropanol (80:20, v/v). The column temperature was 25℃, and the flow rate was 1.0 mL/min. The six tetralone derivative enantiomers were separated on a chiral stationary phase of Chiralpak IC by HPLC. The column has high enantiomeric selectivity to the six tetralone derivative enantiomers.

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Detection of 1,4-dioxane in water by membrane extraction-gas chromatography/differential mobility spectrometry LIANG Xixi, CHEN Chuang, WANG Weiguo, LI Haiyang 2014, 32 (8):  837-842.  DOI: 10.3724/SP.J.1123.2014.04035 Abstract ( 875 )   [Full Text(HTML)] () PDF (1514KB) ( 308 )   The method of detecting trace 1,4-dioxane in water using membrane extraction coupled with gas chromatography/differential mobility spectrometry (GC/DMS) was developed. The parameters including radio frequency voltage, sampling flow rate, permeation time and trapping time were optimized to 1000 V, 50 mL/min, 30 min and 150 s, respectively. The linear range for dioxane was obtained from 2.0 μg/L to 20.0 μg/L. The LOD was found to be 0.67 μg/L. The specificity towards 1,4-dioxane in the presence of five chlorinated hydrocarbons was improved by using two-dimensional GC separation with optimized DMS compensation voltage. This method paves a way for developing field-deployable sensors for real-time monitoring contaminants in groundwater.

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Pollution status of phenolic compounds in the soil and sediment from a chemical industrial park along the Yangtze River CHEN Jiexia, WEI Enze, XIAN Qiming 2014, 32 (8):  843-848.  DOI: 10.3724/SP.J.1123.2014.03041 Abstract ( 778 )   [Full Text(HTML)] () PDF (2222KB) ( 302 )   A determination method of 12 phenolic compounds in soil and sediment samples by gas chromatography-mass spectrometry (GC-MS) analysis coupled with accelerated solvent extraction (ASE) and gel permeation chromatography (GPC) for clean-up was developed. The method detection limits (MDLs) varied from 0.410 μg/kg to 13.1 μg/kg (dry weight), and the average recoveries ranged from 70.7% to 122% with the relative standard deviations (RSDs) of 1.2% to 16%. Based on this method, the levels of 12 phenolic compounds were investigated in 17 soil surrounding a chemical industrial park along the Yangtze River and seven sediment samples collected in the river. It was found that 11 of the 12 phenolic compounds were detected in all of the 24 samples, and only hydroquinone was below the MDL. The contents of the total 12 phenolic compounds were 10.16-30.66 mg/kg in the soil and 18.00-29.83 mg/kg in the sediment, with the average contents of 18.26 and 22.51 mg/kg respectively. It showed that 4-nitrophenol, 4-chloro-3-methylphenol, 2-chlorohydroquinone, 2-methyl-4,6-dinitrophenol and 2,4,6-trichlorophenol were five major phenolic contaminants in the soil and sediment in this study. The pollution levels of the 12 phenolic compounds were low in the soil of the chemical industrial park as well as in the sediment of the Yangtze River, which implied a comparatively low risk for the environment.

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Determination of flumorph and dimethomorph residues in vegetables by improved QuEChERS-gas chromatography-mass spectrometry DING Liping, CAI Chunping, WANG Danhong 2014, 32 (8):  849-854.  DOI: 10.3724/SP.J.1123.2014.04030 Abstract ( 931 )   [Full Text(HTML)] () PDF (1152KB) ( 369 )   To determine the residues of flumorph and dimethomorph in vegetables, a method was established with improved QuEChERS-gas chromatography coupled to mass spectrometry (GC-MS). With acetonitrile as the extraction solvent, the samples were pretreated with the improved QuEChERS method including extraction, salting-out and purification processes. Then all the sample extracts were analyzed with GC-MS in selected-ion monitoring (SIM) mode, and quantified by matrix-matched standard solution in external standard method. Under electron ionization conditions, the analysis was carried out with a capillary column (DB-5 MS, 30 m×0.25 mm×0.25 μm) at a flow rate of 1.1 mL/min. The quantitation was performed to detect ions of m/z 285, 371, 165 for flumorph and m/z 301, 387, 165 for dimethomorph. Good linearity was obtained in the range of 10-1000 μg/kg for both pesticides with correlation coefficients greater than 0.999. The recovery experiments were carried out by spiking blank samples of ginger, tomato, carrot, spinach, cabbage and tremella at the three levels of 10, 20 and 100 μg/kg. For both pesticides in different matrices, the limits of detection (S/N=3) were in the range of 0.67-2.42 μg/kg. The average recoveries of flumorph and dimethomorph ranged from 71% to 116% with the relative standard deviations (RSDs) in the range of 1.8%-14.7%. Meanwhile, the pyrolysis mechanism and matrix effect for the determination of flumorph and dimethomorph in vegetables were investigated in this study. The method is simple, rapid and accurate, and can be used for the routine analysis of flumorph and dimethomorph in vegetables.

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Simultaneous determination of cyhexatin, triphenyltin and fenbutatin oxide residues in fruits and vegetables by Grignard derivatization and gas chromatography coupled to tandem mass spectrometry CUI Zongyan, SUN Yang, GE Na, ZHANG Jinjie, LIU Yongming, LI Adan, CAO Yanzhong 2014, 32 (8):  855-860.  DOI: 10.3724/SP.J.1123.2014.04031 Abstract ( 1105 )   [Full Text(HTML)] () PDF (1198KB) ( 399 )   A method for the simultaneous determination of cyhexatin, triphenyltin and fenbutatin oxide residues in fruits and vegetables was developed by Grignard derivatization and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). The samples were firstly digested by HCl/THF (1:10, v/v), then extracted by hexane and followed by the derivatization with Grignard reagent (EtMgBr). Then after purification using florisil SPE columns, the sample extracts were finally analyzed by GC-MS/MS. The qualitative and quantitative determinations of the three organotin pesticides were performed by the tandem mass in multiple reaction monitoring (MRM) mode. By using apple as a representative matrix, the limits of detection (LODs) obtained by the proposed method for cyhexatin, triphenyltin and fenbutatin oxide were 2.0, 1.5 and 3.4 μg/kg (as Sn), respectively. The average recoveries for the three organotin pesticides were in the range of 72.4%-107.1% at the spiked levels of 10, 20, 50 and 200 μg/kg (as Sn) and the relative standard deviations (RSDs) ranged from 0.4% to 14.2%. The proposed method was validated to have good linearity, high sensitivity, selectivity and accuracy for the simultaneous determination of cyhexatin, triphenyltin and fenbutatin oxide in fruits and vegetables. The sensitivity of this method can meet the requirements of the inspection for the three organotin pesticides at the level of maximum residue limits (MRLs) set by China and some other countries.

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Simultaneous determination of ten phytohormones in five parts of Sargasum fusiforme (Hary.) Seichell by high performance liquid chromatography-triple quadrupole mass spectrometry LI Yan, XU Jilin, ZHENG Liyang, LI Min, YAN Xiaojun, LUO Qijun 2014, 32 (8):  861-866.  DOI: 10.3724/SP.J.1123.2014.03049 Abstract ( 799 )   [Full Text(HTML)] () PDF (819KB) ( 390 )   A method for the simultaneous determination of indole-3-acetic acid, N6-(2-isopentenyl) adenosine, N6-(2-isopentenyl) adenine, trans-zeatin riboside, zeatin, strigolactone, abscisic acid, salicylic acid, gibberellin A3 and jasmonic acid in five different parts of main branch, lateral branch, primary leaf, secondary leaf and stem of Sargasum fusiforme (Hary.) Seichell was established by high performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-TQMS). The samples were extracted with methanol/water/formic acid (15:4:1, v/v/v)(containing 0.5% 2,6-di-tert-butyl-4-methylphenol, BHT) after vacuum freeze-drying. The separation was performed on a Hypersil Gold C18 column by using methanol and water as mobile phases with gradient elution. The analytes were detected by tandem mass spectrometry in selected reaction monitoring (SRM) mode. The electrospray ionization (ESI) source was used for the quantitative analysis in the positive mode or negative mode. Under the optimized conditions, the correlation coefficients (r) of the ten phytohormones were from 0.9989 to 1.0000 in the linear ranges. The detection limits of the ten phytohormones were 0.0012-4.6512 μg/L. The average recoveries were 72.24%-91.31% with the relative standard deviations not more than 6.59%. In the five parts of fresh Sargasum fusiforme (Hary.) Seichell samples, the contents of the ten phytohormones were from not detected to 4041.431 ng/g. This method has good sensitivity, precision, recovery, and can be used to simultaneously determine the phytohormones.

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Simultaneous determination of 18β-agonist residues in feed using QuEChERS sample preparation and high performance liquid chromatography-tandem mass spectrometry ZHENG Ling, WU Yujie, ZHAO Yongfeng, LI Lihua, MA Yanjuan 2014, 32 (8):  867-873.  DOI: 10.3724/SP.J.1123.2014.03029 Abstract ( 922 )   [Full Text(HTML)] () PDF (1974KB) ( 325 )   A multi-residue method was developed for the simultaneous determination of 18 β-agonist residues (clenbuterol, ractopamine, penbutolol, tulobuterol, etc) in feed by using QuEChERS sample preparation and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The feed samples were dispersed by water, then the analytes were extracted with acetonitrile containing 4%(v/v) ammonia and cleaned up by QuEChERS method with 25 mg octadecylsilyl (C18) and 50 mg primary secondary amine (PSA) adsorbents. The separation of compounds was carried on an Agilent ZORBAX Eclipse XDB-C18 column (50 mm×4.6 mm, 1.8 μm) by a gradient elution using methanol-0.1%(v/v) formic acid aqueous solution as mobile phase. The analytes were detected by tandem mass spectrometry under multiple reaction monitoring (MRM) mode with positive electrospray ionization (ESI+) and quantified by the matrix-matched external standard method. The results showed that the calibration curves of the 18 β-agonists were linear in the range of 5-200 μg/L with correlation coefficients of 0.9912-0.9995. The average recoveries of the 18 analytes at three spiked levels of 0.05, 0.1 and 0.5 mg/kg ranged from 78.4% to 107.1% with the relative standard deviations (RSDs) of 3.5%-12.3%. The limit of quantification (LOQ, S/N≥10) was 0.05 mg/kg for each analyte . The developed method is simple and sensitive, and can be applied as a screen and confirmatory method for the analysis of β-agonists in feed.

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Determination of 14 sulfonamide residues in shrimps by high performance liquid chromatography coupled with post-column derivatization HUANG Dongmei, HUANG Xuanyun, GU Runrun, HUI Yunhua, TIAN Liangliang, FENG Bing, ZHANG Xuan, YU Huijuan 2014, 32 (8):  874-879.  DOI: 10.3724/SP.J.1123.2014.04009 Abstract ( 734 )   [Full Text(HTML)] () PDF (823KB) ( 405 )   A method for the determination of 14 sulfonamide residues in shrimps by high performance liquid chromatography coupled with post-column derivatization was established. The sulfonamide residues were extracted with ethyl acetate after adding sulfapyridine as internal standard. The extracts were vacuum-concentrated and reverse-extracted by 2 mol/L hydrochloric acid solution for clean-up, and then the hydrochloric acid solution was defatted with n-hexane. The solution after filtration was blended with a mixed solution of methanol, acetonitrile and 3.5 mol/L sodium acetate solution (5:5:20, v/v/v). The sulfonamides were separated on a C18 column by RP-HPLC and on-line derivatized with a fluorescamine and detected with a fluorescence detector. The standard addition method was used for quantitative analysis. The parameters of post-column derivatization system, such as concentration of fluorescamine solution, velocity of reagent solution and reaction temperature, were optimized. The calibration curves of the method showed good linearity in the range of 5-200 μg/L. The limits of quantification (LOQ, S/N=10) were 1.0-5.0 μg/kg for the 14 sulfonamides. The recoveries were 77.8%-103.6% in the spiked range of 1.0-100.0 μg/kg in shrimps with the relative standard deviations of 2.9%-9.1% (n=6). The results indicated that the method is sensitive, efficient and more accurate. It is suitable for the simultaneous determination of the 14 sulfonamide residues in shrimps.

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Chromatographic separation of aminoglutethimide enantiomers on cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase LIN Xiaojian, GONG Rujin, LI Ping, YU Jianguo 2014, 32 (8):  880-885.  DOI: 10.3724/SP.J.1123.2014.04022 Abstract ( 837 )   [Full Text(HTML)] () PDF (811KB) ( 373 )   Aminoglutethimide (AG) has been used clinically as a drug in the treatment of hormone-dependent metastatic breast cancer. It was reported that S-(-)-AG enantiomer had small activity and sometimes might cause side effects. Therefore, it was of great significance to obtain the high-purity R-(+)-AG by enantioseparation. In this work, aminoglutethimide enantiomers were separated by high performance liquid chromatography (HPLC) using an analytical column which was packed with cellulose tris(3,5-dimethylphenylcarbamate) stationary phase (Chiralcel OD-H). The solubilities of racemic AG in two different solvent compositions, n-hexane/ethanol and n-hexane/isopropanol, were measured, separately. The effects of alcohol content and monoethanolamine additive on the separation performance of racemic AG by HPLC were investigated. According to the experiments, n-hexane-ethanol (30:70, v/v) with 0.1% monoethanolamine additive was selected as the mobile phase. The separation factor, resolution, asymmetry factor, number of theoretical plates and maximum column capacity were measured and analyzed for the chromatographic separation of racemic AG at a flow-rate of 0.6 mL/min and column temperature of 25-40℃, with Chiralcel OD-H as stationary phase and n-hexane-ethanol (30:70, v/v) with 0.1% monoethanolamine as mobile phase. This work provides the basic information of chromatographic separation for the batch and continuous production of aminoglutethimide enantiomers.

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Determination of propargite, tebuconazole and bromopropylate pesticide residues in Taiwan green jujubes by gas chromatography-tandem mass spectrometry ZHANG Qun, LIU Chunhua, WU Nancun, WU Xiaofang, LI Shuhuai 2014, 32 (8):  886-889.  DOI: 10.3724/SP.J.1123.2014.04014 Abstract ( 1116 )   [Full Text(HTML)] () PDF (781KB) ( 444 )   An analytical method was established for the determination of propargite, tebuconazole and bromopropylate in Taiwan green jujubes (Zizyphus mauritiana Lam) by gas chromatography-tandem mass spectrometry (GC-MS/MS). The sample was extracted with acetonitrile from the Taiwan green jujubes after treated with a homogenizer. The organic phase was then separated from water phase by adding NaCl. The extract was further purified on a carbon/NH2 cartridge with elution solvents of acetonitrile/toluene (3:1, v/v). Finally, the target analytes were separated by a capillary gas chromatographic column SLB-5MS (30 m×0.25 mm×0.25 μm). A tandem quadrupole mass spectrometer operated in either full scan mode or in MS/MS mode for multiple reaction monitoring (MRM) was used for the qualitative and quantitative analysis of the constituents, respectively. The results showed that the average recoveries of the three pesticides ranged from 75.8% to 103.6% with the RSDs of 1.7%-9.3% at the spiking levels from 0.01 mg/kg to 0.50 mg/kg (n=5). The calibration curves showed good linearity in the range of 0.01-0.50 mg/kg, with the determination coefficients over 0.99 (R2>0.99). The limits of quantification (LOQs) were 0.01 mg/kg for propargite, tebuconazole and bromopropylate in Taiwan green jujubes. The method is available for the determination of propargite, tebuconazole and bromopropylate pesticide residues in Taiwan green jujubes.

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Determination of residual glycol ethers in leather and leather products by gas chromatography/mass spectrometry WANG Chengyun, ZHANG Weiya, LI Lixia, SHEN Yalei, LIN Junfeng, XIE Tangtang, CHU Naiqing 2014, 32 (8):  890-896.  DOI: 10.3724/SP.J.1123.2014.04008 Abstract ( 828 )   [Full Text(HTML)] () PDF (819KB) ( 370 )   An effective method was established for the simultaneous determination of residual glycol ethers in leather and leather products by gas chromatography/mass spectrometry. Glycol ethers in leather and leather products were ultrasonically extracted at 45℃, using ethyl acetate as the extraction solvent. The extracts were purified by solid phase extraction (SPE) columns, and then analyzed by gas chromatography/mass spectrometry in selected ion monitoring mode. The content of each analyte was calibrated by external standard method. The limit of detection of ethylene glycol ethyl ether (EGEE) was 0.10 mg/kg under the condition of signal to noise (S/N) of 3 and the limits of the other 11 glycol ethers were all less than 0.05 mg/kg. The spiked recoveries varied from 81.2% to 95.5% at three different spiked levels with the relative standard deviations (RSDs) ranged from 1.4% to 6.6%. The proposed method is simple, rapid and accurate, with the limits of detection much less than the requirements of the Regulation Concerning Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) of European Union. It is applicable to the determination of residual glycol ethers in leather and leather products, and provides a reference for the relevant testing standards.

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Matrix effect and application of field-amplified sample injection in the analysis of four tetracyclines in waters by capillary electrophoresis LI Aimei, HUANG Zhuo, LU Wenping, XU Zhongqi 2014, 32 (8):  897-903.  DOI: 10.3724/SP.J.1123.2014.03044 Abstract ( 823 )   [Full Text(HTML)] () PDF (950KB) ( 421 )   The system abilities of two chromatographic techniques, capillary electrophoresis (CE) and high performance liquid chromatography (HPLC), were compared for the analysis of four tetracyclines (tetracycline, chlorotetracycline, oxytetracycline and doxycycline). The pH, concentration of background electrolyte (BGE) were optimized for the analysis of the standard mixture sample, meanwhile, the effects of separation voltage and water matrix (pH value and hardness) effects were investigated. In hydrodynamic injection (HDI) mode, a good quantitative linearity and baseline separation within 9.0 min were obtained for the four tetracyclines at the optimal conditions; the analytical time was about half of that of HPLC. The limits of detection (LODs) were in the range of 0.28-0.62 mg/L, and the relative standard deviations (RSDs) (n=6) of migration time and peak area were 0.42%-0.56% and 2.24%-2.95%, respectively. The obtained recoveries spiked in tap water and fishpond water were at the ranges of 96.3%-107.2% and 87.1%-105.2%, respectively. In addition, the stacking method, field-amplified sample injection (FASI), was employed to improve the sensitivity, and the LOD was down to the range of 17.8-35.5 μg/L. With FASI stacking, the RSDs (n=6) of migration time and peak area were 0.85%-0.95% and 1.69%-3.43%, respectively. Due to the advantages of simple sample pretreatment and fast speed, CE is promising in the analysis of the antibiotics in environmental water.