List of Issues

Chinese Journal of Chromatography
2005, Vol. 23, No. 6
Online: 30 November 2005

Previous Issue    Next Issue



For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

研究报告

Select

Preparation of Weak Cation-Exchange Packings Based on Monodisperse Porous Poly (Chloromethylstyrene-co- Divinylbenzene) Beads and Its Applications in Separation of Biopolymers LI Long, MA Guijuan, GONG Bolin, 2005, 23 (6):  567-572.  Abstract ( 2108 )   [Full Text(HTML)] () PDF (287KB) ( 1042 )   Monodisperse polystyrene seed particles were prepared by dispersion polymerization of styrene in ethanol and water under a nitrogen atmosphere using benzoyl peroxide as an initiator. Then the monodisperse, porous poly (chloromethylstyrene-co-divinylbenzene) beads in the range of 6-15 μm were prepared by one-step swelling and polymerization method. Based on this media, a new hydrophilic weak cation exchange stationary phase (WCX) for high performance liquid chromatography was synthesized by a new chemical modification method. The stationary phase was evaluated on the behavior of ion exchange, separability, and hydrophilicity. Effects of the nature of salts and pH value on the separation and retention of proteins of the stationary phase were investigated in details. It was found that the WCX resin follows ion exchange chromatographic retention mechanism. It was also used for the rapid separation and purification of lysozyme from egg white in only one step. The purity was found more than 96% and specific bioactivity of the purified lysozyme was as high as 71184 U/mg.

Select

Preparation and Determination of 1-O-Acetylbritannilactone in Inula Britannica L. WANG Yunzhi, SHI Xiaowei, FU Yan, CHENG Wei, ZHANG Diqun, ZHA Jianpeng 2005, 23 (6):  573-576.  Abstract ( 2195 )   [Full Text(HTML)] () PDF (219KB) ( 735 )   To prepare reference substance for quality control of Inula Britannica L., 1-O-acetylbritannilactone was extracted and separated from chloroform extraction of Inula Britannica L. Chemical structure of the 1-O-acetylbritannilactone product was elucidated by ultraviolet spectrometry (UV), infrared spectroscopy (IR), nuclear magnetic resonance (NMR) and mass spectrometry (MS), and the results were in agreement with the reference. The purity of the 1-O-acetylbritannilactone product was 99.5%, which satisfies the need of reference substances of traditional Chinese medicines. A method of high performance liquid chromatography-evaporative light scattering detection (HPLC-ELSD) is described for the determination of 1-O-acetylbritannilactone in Inula Britannica L. The chromatographic conditions include Hypersil ODS-2 column, a mixture of methanol-water (52∶48, v/v) with the flow rate of 1.0 mL/min used as mobile phase. The temperature of drift tube of the ELSD was 90 ℃. Flow rate of carrier gas was 2.5 L/min. Linear range of 1-O-acetylbritannilactone was 1.37-8.21 μg (r=0.9998). The average recovery of 1-O-acetylbritannilactone was 100.2% with the relative standard deviation (RSD) of 1.3%(n=6). The method is simple, accurate, time saving and reproducible.

Select

Determination of Chloramphenicol Residues in Milk by Reversed-Phase High Performance Liquid Chromatography with Fluorescence Detection PAN Yingyu, XU Qian, KANG Xuejun, ZHANG Jianxin 2005, 23 (6):  577-580.  Abstract ( 2548 )   [Full Text(HTML)] () PDF (153KB) ( 989 )   A high performance liquid chromatographic method with fluorescence detection for the determination of chloramphenicol (CAP) residues in milk was developed. Although CAP itself is non-fluorescent the aromatic nitro group of CAP could be reduced to aromatic primary amino group and fluorescamine can be used as a selective reagent for primary amines. Therefore, the CAP was derivatized with fluorescamine prior to injection in this project. The HPLC method was performed on a Diamond C18 column (250 mm×4.6 mm i.d., 4.0 μm) with the mobile phase composed of sodium acetate buffer (0.02 mol/L, pH 6.0)-acetonitrile-tetrahydrofuran (76∶16∶8, v/v/v). The flow rate of the mobile phase was set at 1.0 mL/min, and the column was maintained at 40 ℃. Analytes were detected by a fluorescence detector at 410 nm excitation and 508 nm emission wavelength. The standard curve was linear in the range from 0.4 μg/L to 800 μg/L. The limit of detection (LOD) was 0.2 μg/L, and the limit of quantitation (LOQ) was 0.4 μg/L. Overall recoveries were between 66.6% and 92.8% with relative standard deviations between 4.5% and 9.4%. The procedure provides a rapid, reliable and sensitive method for the determination of CAP in milk.

Select

Determination of Carbendazim and Thiabendazole in Tomatoes by Solid-Phase Microextraction Coupled with High Performance Liquid Chromatography and Fluorescence Detection HU Yanxue, YANG Xiumin, WANG Zhi, WANG Chun, ZHAO Jin 2005, 23 (6):  581-584.  Abstract ( 2135 )   [Full Text(HTML)] () PDF (166KB) ( 1119 )   A novel method for the determination of carbendazim (MBC) and thiabendazole (TBZ) in tomatoes by solid-phase microextraction (SPME) coupled with high performance liquid chromatography (HPLC) and fluorescence detection was developed. The experimental conditions of SPME, including extraction fiber, extraction time, extraction temperature, desorption time, desorption solvent, desorption mode, pH value, organic solvent and ionic strength, and HPLC conditions were optimized. The SPME for MBC and TBZ was performed on a 65 μm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 50 min at room temperature with the solution being stirred at 1100 r/min. The florescence detection was made at 315 nm with excitation wavelength at 280 nm. The method is linear for MBC and TBZ over the range assayed from 0.01 to 1.0 mg/kg tomatoes with the detection limits of 0.003 mg/kg and 0.001 mg/kg and the correlation coefficients of 0.9958 and 0.9967, respectively. The average recoveries for MBC and TBZ were 83.5% and 85.6% with the relative standard deviations (RSDs) of 6.5% and 3.8%, respectively. The method is fast, simple, sensitive, solvent-free and suitable for the determination of MBC and TBZ in tomatoes.

专论综述

Select

Porous Monoliths: Stationary Phases of Choice for High Performance Liquid Chromatography in Various Formats SVEC Frantisek 2005, 23 (6):  585-594.  Abstract ( 1967 )   [Full Text(HTML)] () PDF (747KB) ( 544 )   Modern porous monoliths have been conceived as a new class of stationary phases for high performance liquid chromatography (HPLC) in classical columns in the early 1990s and later extended to the capillary format. These monolithic materials are prepared using simple processes carried out in an external mold (inorganic monoliths) or within the confines of the column (organic monoliths and all capillary columns). These methods afford macroporous materials with large through-pores that enable applications in a rapid flow-through mode. Since all the mobile phase must flow through the monolith, the convection considerably accelerates mass transport within the monolithic separation medium and improves the separations. As a result, the monolithic columns perform well even at very high flow rates. The applications of monolithic capillary columns are demonstrated on numerous separations in the HPLC mode.

Select

Hydride-Based Separation Materials for High Performance Liquid Chromatography and Open Tubular Capillary Electrochromatography PESEK Joseph J, MATYSKA Maria T 2005, 23 (6):  595-608.  Abstract ( 1747 )   [Full Text(HTML)] () PDF (782KB) ( 515 )   Silica hydride is a recent development in chromatographic support materials for high performance liquid chromatography (HPLC) where hydride groups replace 95% of the silanols on the surface. This conversion changes many of the fundamental properties of the material as well as the bonded stationary phases that are the result of further chemical modification of the hydride surface. Some unique chromatographic properties of hydride-based phases are described as well as some general application areas where these bonded materials may be used in preference to or have advantages not available from typical stationary phases. The fabrication, properties and applications of etched chemically modified capillaries for electrophoretic analysis are also reviewed. It is shown that the etching process creates a surface that is fundamentally different than a bare fused silica capillary. The new surface matrix produces unique electroosmotic flow properties and is more compatible with basic and biological compounds. After chemical modification of the surface, the bonded organic moiety (stationary phase) contributes to the control of migration of solutes in the capillary. Both electrophoretic and chromatographic processes take place in the etched chemically modified capillaries leading to a variety of experimental variables that can be used to optimize separations. A number of examples of separations on these capillaries are described.

Select

Progress in the Determination of Trace Polycyclic Aromatic Hydrocarbons in Complex Matrices DONG Xinyan, YANG Yiwen, REN Qilong 2005, 23 (6):  609-615.  Abstract ( 2076 )   [Full Text(HTML)] () PDF (206KB) ( 1257 )   The analytical methods of polycyclic aromatic hydrocarbons （PAHs) in different samples, e.g., vegetable oils, waters and soils, have been reviewed. The sample pretreatment steps play a key role during the analysis due to the very low PAHs contents. The pretreatment methods for water samples include liquid-liquid extraction, solid phase extraction, etc. The pretreatment methods for soil samples include Soxhlet extraction, ultrasonic extraction, microwave assisted extraction, accelerated solvent extraction, and supercritical fluid extraction, etc. The pretreatment methods for vegetable oils include saponification, liquid-liquid partitioning, caffeine complexation, solid phase extraction, and supercritical fluid extraction, etc. Gas chromatography with mass spectrometry and high performance liquid chromatography (HPLC) with fluorescence detection are mainly used for separation and detection. The novel on-line determination method, e.g., the coupling of liquid chromatography with high performance liquid chromatography, or with gas chromatography may obtain ideal results. Fifty-two references are cited.

研究简报

Select

Preparation of Porous Silica Microspheres with High Porosity Using Base-Dissolving Method ZHAO Rui, LI Xinhui, LIU Guoquan 2005, 23 (6):  616-618.  Abstract ( 1936 )   [Full Text(HTML)] () PDF (123KB) ( 852 )   A novel method was proposed and studied for the preparation of porous silica with high porosity using base-dissolving technology. The relationships between the removal of silica and the base concentration, the reaction temperature as well as the reaction time were evaluated. The amount of silica removed from silica spheres was increased and silica-dissolving rate was also accelerated along with the increase of NaOH concentration. This was due to the damage of some inner walls of the porous silica and the dissolution of small fragments into the base solution. The amount of silica removed was in direct proportion to the reaction temperature and reaction time. Moreover, the specific pore volumes were linearly increased along with the increase of the amount of silica removed. The treated silica particles remained as homogeneous spheres and the changes of the particle diameter were not observed. Under the optimized conditions with the NaOH solution of 1.25 mol/L, the reaction temperature of 25 ℃ and the reaction time of 3.0 h, the original silica spheres with the diameter of 4-5 μm, the pore size of 8 nm and the specific pore volume (Vp) of 1.4 cm3/g were modified to the high-porosity silica with the diameter of 4-5 μm, the pore size of 14 nm and the Vp of 3.2 cm3/g. The porosity of the silica microspheres was changed from 75% to 88%. This high-porosity silica was suitable for the preparation of high performance gel filtration packings.

Select

Synthesis and Evaluation of High Performance Gel Filtration Chromatography Packing of KH-s-GFC300 ZHAO Rui, LI Xinhui, LIU Guoquan 2005, 23 (6):  619-621.  Abstract ( 2390 )   [Full Text(HTML)] () PDF (122KB) ( 661 )   A novel packing for high performance gel filtration chromatography (GFC) was synthesized and characterized. High porosity silica prepared by base-dissolving method was used as the matrix. γ-(2,3-Epoxy propoxyl) propyltrimethoxysilane was used as the ligand and covalently bonded onto the silica matrix. After acidic hydrolysis, the epoxy groups were converted to the diol groups. Because a condensation tube filled with water at 70 ℃ was used in the grafting reaction, the resulting methanol could easily be discharged from the reaction system to shift the reaction equilibrium to achieve high ligand density. The hydrolysis condition greatly affects ligand density and column efficiency. The high column efficiency is observed when the ligand density is between 2.6 and 3.5 μmol/m2. Several proteins, such as cytochrome C, chymotrypsin, ovalbumin, bovine serum albumin, aldolase, ferritin, insulin, γ-globulin, phosphorylase, actin, carbonic anhydrase, were used to characterize the separation properties of the resulting high performance GFC column. It was shown that the excluded limit of relative molecular mass for the separation of bio-molecules was 300000. The recovery yield of bovine serum albumin was 99%.

Select

Fast Separation of Nicotinamide and Nicotinic Acid with Molecularly Imprinted Monolithic Column LI Zhiwei, LIU Shubin, YANG Gengliang, LI Baozhi, CHEN Yi 2005, 23 (6):  622-625.  Abstract ( 2274 )   [Full Text(HTML)] () PDF (143KB) ( 1859 )   Nicotinamide has been employed as template for the preparation of molecularly imprinted monolithic polymer （MIP） which was used as liquid chromatographic stationary phase. It showed that the nicotinamide-MIP monolithic column was capable of recognizing the difference between nicotinamide and nicotinic acid, while the non-imprinted polymer had no such ability. The content of organic solvent, flow rate and pH of the mobile phase were investigated in the experiments. The following high performance liquid chromatographic conditions were selected: column, 50 mm×4.6 mm i.d.; mobile phase, water; flow rate, 7.0 mL/min; experiment temperature, room temperature. The resolution between nicotinamide and nicotinic acid was 1.8. The results showed that the two compounds could be separated by the nicotinamide-MIP monolithic column. The column is very useful for the enrichment and detection of nicotinamide in body fluids.

Select

Analysis of Four Components in Fufang Danshen Tablets by High Performance Liquid Chromatography with Electrochemical and Ultraviolet Detections SUO Zhirong, QIN Haiyan, CAO Wei, LIU Wenzhe, ZHENG Jianbin 2005, 23 (6):  626-629.  Abstract ( 2225 )   [Full Text(HTML)] () PDF (149KB) ( 753 )   A rapid and accurate method for the simultaneous separation and determination of protocatechuic acid, protocatechuic aldehyde, caffeic acid and tanshinone ⅡA in Fufang Danshen Tablets by high performance liquid chromatography has been established. The former three constituents were detected by electrochemical array detector (ECD) and the last one by ultraviolet diode array detector (DAD). The separation was performed on a Zorbax SB-C18 column (150 mm×4.6 mm i.d., 5.0 μm) by gradient elution with methanol and 0.4% aqueous phosphoric acid as mobile phase at a flow rate of 1.0 mL/min. The detections were done at 0.7 V, 270 nm and 30 ℃. The results showed that the linear ranges were 0.3-9.0 mg/L for protocatechuic acid, 1.1-54.0 mg/L for protocatechuic aldehyde, 1.1-11.1 mg/L for caffeic acid and 5.2-52.0 mg/L for tanshinone ⅡA. The average recoveries (n= 6) were 97.8% with relative standard deviation (RSD) of 2.15% for protocatechuic acid, 98.2% with RSD of 2.07% for protocatechuic aldehyde, 97.6% with RSD of 2.18% for caffeic acid and 97.2% with RSD of 2.07% for tanshinone ⅡA. These four components were separated successfully from each other. The sensitivities of detection of protocatechuic acid, protocatechuic aldehyde and caffeic acid with ECD were 11.0-25.3 times greater than those with DAD. The study provides a scientific basis for the quality control of Fufang Danshen Tablets.

Select

Quick Optimization of High Performance Liquid Chromatographic Conditions for Separation of Flavones of Astragalus XU Qing, WANG Longxing, ZHANG Xi, JIN Gaowa, XIAO Hongbin, LIANG Xinmiao 2005, 23 (6):  630-632.  Abstract ( 2017 )   [Full Text(HTML)] () PDF (125KB) ( 790 )   An analytical method for flavones of Astragalus has been developed and a process of high performance liquid chromatographic (HPLC) condition optimization has been elaborated. The LC retention parameters of 34 components were obtained quickly by using three linear gradient elutions. Overlapping separation range map (OSRM), which is related to the separation quality and the analysis time, was utilized to search the optimised stepwise gradient method for HPLC analysis of flavones of Astragalus. Finally, the optimised stepwise gradient elution conditions were set up with the help of this map. Under the optimised conditions, the sample of flavones of Astragalus was well separated in reasonable time. The method is more convenient than that using a series of isocratic elutions.

Select

Determination of Apomorphine, Sildenafil and Alprostadil in Medicines for Erectile Dysfunction by High Performance Liquid Chromatography-Mass Spectrometry XU Yuanjin, XU Guiping 2005, 23 (6):  633-635.  Abstract ( 2421 )   [Full Text(HTML)] () PDF (137KB) ( 958 )   A high performance liquid chromatography-mass spectrometry (LC-MS) analytical method for illicit drugs, apomorphine, sildenafil and alprostadil, in medicines for erectile dysfunction has been developed. The samples were extracted with methanol using ultrasound-assisted extraction. The chromatographic separation was performed on a Zorbax Eclipse XDB-C18 column using acetonitrile-0.5% formic acid aqueous solution as mobile phase. The three compounds were identified by retention time and m/z and quantified by peak area. The results demonstrated that the linear ranges were 50.0-5000.0 μg/L, 10.0-1000.0 μg/L, 40.0-4000.0 μg/L, with detection limits of 20.0, 4.0, 10.0 μg/L for apomorphine, sildenafil and alprostadil, respectively. The average recoveries and the relative standard deviations were 89%-95% and 9.5%-11%. The method is simple, rapid, accurate and suitable for the simultaneous determination of these drugs in medicines for erectile dysfunction.

Select

Determination of Residual Sulfonamides in Meat by High Performance Liquid Chromatography with Solid-Phase Extraction ZHANG Yan, WU Yinliang 2005, 23 (6):  636-638.  Abstract ( 2152 )   [Full Text(HTML)] () PDF (128KB) ( 843 )   A method was developed for determining residual sulfonamides (SAs) such as sulfamethazine (SM2), sulfamonomethoxine (SMM), sulfamethiazole (SMZ), sulfadimethoxine (SDM) and sulfaquinoxaline (SQ) in pork and chicken using solid-phase extraction (SPE) and high performance liquid chromatography (HPLC) with a photodiode array detector. The samples were extracted with ethyl acetate. An NH2 column was used for clean up. For the HPLC determination, an Intersil ODS-2 column was used with a mixture of methanol-acetonitrile-water-acetic acid (2∶2∶9∶0.2, v/v) as the mobile phase. The detection limits (S/N=3) were 3 μg/kg for SM2， SMM and SMZ, and 7 μg/kg for SDM and SQ. The quantitation limits (S/N=10) were 10 μg/kg for SM2, SMM and SMZ, and 25 μg/kg for SDM and SQ. The linear ranges were 30-5000 μg/L for SM2, SMM and SMZ, and 60-5000 μg/L for SDM and SQ. The recoveries were between 73.2% and 97.3% with the relative standard deviations between 2.5% and 11.6% originated from the spiked level of 50 μg/kg.

Select

Determination of Papaverine in Seeds of Papaver somniferum L.and Soup of Chafing Dish by High Performance Liquid Chromatography-Fluorescence Detection PI Li, HU Fengzu, SHI Zhixian 2005, 23 (6):  639-641.  Abstract ( 2200 )   [Full Text(HTML)] () PDF (117KB) ( 817 )   A method of reversed-phase high performance liquid chromatography coupled with fluorescence detection was developed for the separation and determination of papaverine in seeds of Papaver somniferum L. and soup of chafing dish. The liquid chromatographic experiment was carried out under the following conditions: the detector was a fluorescence with excitation wavelength at 285 nm and emission wavelength at 355 nm. An RP-C18 column (250 mm×4.6 mm i.d., 5 μm) was used. The mobile phase was a mixture of methanol and 0.02 mol/L ammonium acetate (70∶30, v/v). The flow rate was 0.8 mL/min. A linear range was obtained from 0.1 ng to 0.1 μg with a good correlation. The lowest detection limit was 0.02 ng. The average recovery of seeds for Papaver somniferum L. was 99.0%-100.8%. The method is rapid, accurate, sensitive and suitable for the separation and determination of papaverine in foods.

Select

Determination of Aliphatic Amines by High Performance Liquid Chromatography with Fluorescence and Atmospheric Pressure Chemical Ionization Detection and Identification by Mass Spectrometry CHEN Xiangming, SHI Yunwei, ZHAO Xian’en, ZHANG Haifeng, YOU Jinmao 2005, 23 (6):  642-645.  Abstract ( 2033 )   [Full Text(HTML)] () PDF (159KB) ( 806 )   Aliphatic amines exist widely in nature. Therefore, quick and precise determination of aliphatic amines is of great significance. A simple and highly sensitive method based on the derivatization of aliphatic amines utilizing 1,2-benzo-3,4-dihydrocarbazole-9-acetic acid (BCAA) as the novel pre-column derivatization reagent followed by high performance liquid chromatography with fluorescence detection and online mass spectrometric identification was developed. Optimum derivatization was obtained by the reaction of aliphatic amines with BCAA at 50 ℃ for 15 min in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDAC) in acetonitrile solvent. The condition of derivatization was mild and the yield of derivative each aliphatic amine was higher than 94%. Derivatives were sufficiently stable to be efficiently analyzed by high performance chromatography without pretreatment. On a reversed-phase BDS-C18 column, twelve aliphatic amine derivatives (C1-C12) were separated under gradient elution with baseline resolution. The precise determining aliphatic amines from soil and wastewater samples was obtained by post-column online mass spectrometric identification with atmospheric pressure chemical ionization(APIC) source under positive mode detection. The established method exhibited excellent reproducibility and recovery. Linear responses were observed with coefficients over 0.9993. The detection limits (at signal-to-noise ratio of 3∶1) were 12-28 fmol.

Select

Comparison of Supercritical Fluid Extraction and Steam Distillation Methods for the Extraction of Essential Oils from Schizonepeta tenuifolia Briq. QIU Qin, LING Jianya, DING Yuping, CHANG Hongwen, WANG Jiang, LIU Tingli 2005, 23 (6):  646-650.  Abstract ( 2403 )   [Full Text(HTML)] () PDF (238KB) ( 1167 )   Essential oil was extracted from Schizonepeta tenuifolia Briq. by supercritical fluid extraction (SFE) and steam distillation (SD). The components extracted were determined by gas chromatography with area normalization method and identified by gas chromatography-mass spectrometry (GC-MS). The optimal chromatographic conditions were: capillary column, SE-54 (30 m×0.25 mm i.d., 0.25 μm); column temperature, 50 ℃(3 min)5 ℃/min180 ℃(2 min)10 ℃/min260 ℃(50 min); split injection, split ratio 1∶50; injector temperature, 280 ℃. Fifty-four components were identified for the essential oils extracted by SFE, and its main components were found to be pulegone, menthone, linoleic acid chloride etc. Thirty-nine components were identified for the essential oil obtained by SD, and its main components were found to be pulegone, menthone, limonene etc. The SFE method is better than the SD method in reliability stability and reproducibility, and is thus well suitable for similar applications involving for extraction of other traditional Chinese herbal medicines.

Select

Extraction and Determination of Volatile Constituents in Leaves of Eucalyptus citriodora TIAN Yuhong, LIU Xiongmin, ZHOU Yonghong, GUO Zhanjing 2005, 23 (6):  651-654.  Abstract ( 2793 )   [Full Text(HTML)] () PDF (179KB) ( 955 )   The volatile constituents in leaves of Eucalyptus citriodora, including oil fraction and water-soluble fraction, were extracted and determined. Oil fraction of volatile components was obtained through steam distillation. Ether was used as the solvent to extract the water-soluble fraction of volatile compounds from the liquid left after steam distillation in order to know the quantity and constituents of volatile compounds dissolved in the water phase. The oil yield in the oil fraction was 1.36%, and the oil yield in the water-soluble fraction was 0.48% (both on fresh weight basis). Both oil fraction and water-soluble fraction were analyzed by gas chromatography-mass spectrometry (GC-MS) method. The results showed that 37 compounds (97.36%) in the oil fraction and 10 compounds (82.05%) in the water-soluble fraction were identified. There were 12 hydrocarbon compounds and 25 oxygenated compounds identified in oil fraction. The major constituents in oil fraction were citronellal (57.00%), followed by citronellol (15.89%) and citronellyl acetate (15.33%). Alcohols dominated the compounds in water-soluble fraction. cis-p-Menthane-3,8-diol(53.43%) and trans-p-menthane-3,8-diol (16.48%) were found to be the major compounds, which have the activity to repel insects. It is concluded that the comprehensive utilization value of leaves of Eucalyptus citriodora was enhanced owing to the extraction of water-soluble volatile components.

Select

Determination of Organic Residues in Macroporous Adsorption Resins by Gas Chromatography JIA Cunqin, LI Yangchun, TU Pengfei, ZHANG Hongquan 2005, 23 (6):  655-658.  Abstract ( 2151 )   [Full Text(HTML)] () PDF (192KB) ( 740 )   A method has been developed for the simultaneous determination of benzene, toluene, xylene, styrene, decane, diethylbenzene, undecane, divinylbenzene, dodecane and naphthalene residues in macroporous adsorption resins(MARs). The organic residues were extracted from resin samples by ultrasonic extraction with dichloromethane and analyzed by gas chromatography. The chromatographic conditions were as follows: a DB-624 capillary column (30 m×0.32 mm i.d.,1.8 μm); carrier gas, nitrogen with a flow rate of 2.5 mL/min; column temperature, programmed from 40 ℃ to 200 ℃ at a rate of 14 ℃/min and kept at 200 ℃ for 1 min; flame ionization detector temperature, 250 ℃; injector temperature, 220 ℃; splitless injection, 1 μL. All the 10 organic residues were separated well in 12 min. The recoveries for spiked standards (n=3) were 73.8%-107.9%. The relative standard deviations were 1.3%-4.4%. The limits of detection were 0.007-0.03 mg/L. This method is sensitive, accurate and quick. Nine commercial MARs and their pretreated samples were assayed, and the results show that the contents of organic residues varied greatly in two kinds of samples. And the pretreated MARs can be used safely in the production of traditional Chinese medicines.

Select

Analysis of By-Products in Photopromoted Carbonylation of Cyclohexene and Carbon Dioxide by Gas Chromatography-Mass Spectrometry GAO Dabin, YIN Jingmei, HU Jiehan, ZHOU Guangyun, JIA Yingping, WANG Rui 2005, 23 (6):  659-662.  Abstract ( 2561 )   [Full Text(HTML)] () PDF (208KB) ( 702 )   The analysis of gas chromatography-mass spectrometry （GC-MS） has been applied more and more in organic chemistry because of the availability of the immediate information from reaction mixture. In some simple reaction systems, the structures can be determined by the comparison of the normal MS with the isotopic MS though usually it is difficult to get structures only from MS. Cyclohexene could also react with acetone to produce by-products in photopromoted carbonylation of cyclohexene with carbon dioxide under ambient conditions. CH3COCH3 and CD3COCD3 were used to analyze those by-products in the carbonylation of cyclohexene with carbon dioxide by GC-MS. The comparison of the normal MS with the isotopic MS from CH3COCH3 and CD3COCD3 was made to make sure if acetone takes part in side-reactions. The molecular weight and mass charge ratio of some related fragments could increase by 3 (one —CH3 from CH3COCH3 ) or 6 (two —CH3 from CH3COCH3 ) when using CD3COCD3 in place of CH3COCH3, which was an efficient way to determine the structures and the fragments in MS. By using this method it was confirmed that 2% derivative of epoxybutane, 4%cyclo-C6H9-C(CH3)2OH and 2%cyclo-C6H11-C(CH3)2OH were formed from the reaction of cyclohexene and acetone. The explanation of the formation of these three compounds was made according to photochemistry and the experimental results.

Select

Investigation on Comparison Method of Chromatographic Fingerprints of Lacquer Coat of Cars and Its Application LI Chen, LIANG Bing, SHI Yanping, JIANG Shengxiang, OU Qingyu 2005, 23 (6):  663-668.  Abstract ( 2013 )   [Full Text(HTML)] () PDF (274KB) ( 620 )   The comparison method of fingerprints of the lacquer coat of cars (LCC) was established by using thermal desorption instrument with gas chromatography. The actual LCC samples were also analyzed. The samples were cut out to proper size and placed in the desorption furnace of the thermal desorption instrument. The volatile organic compounds in LCC were desorbed from the lacquer coat samples in the furnace under the chosen temperature, then separated in the capillary column and detected on a flame ionization detector of gas chromatography. The incipient judgment whether the two fingerprints of LCC were the same can be made from the contour and figure of the chromatograms. To make farther study of the two similar fingerprints, the overlap ratio of the peaks and relative retention values were given in the article. The two LCC samples can be regarded as the same if the overlap ratio of peaks was more than 90%, and the similarity of the ratio of relative retention times rt2 and rt1 and relative peak areas rA2 and rA1 in the two fingerprints were more than 99% and 70%, respectively. The method is good in repeatability and is easily carried out. The peaks in the fingerprint can be readily recognized. The fingerprint was characterized quantitatively. The method can be used in the department of traffic police and the comparison result can be used as material evidence in the court.

Select

Separation of Proteins by Gradient Pressurized Capillary Electrochromatography ZHAO Liangjuan, ZOU Juanjuan, WANG Xiuli, YAN Chao, GAO Ruyu, LIU Mingyu, Lv Xianyu 2005, 23 (6):  669-672.  Abstract ( 2259 )   [Full Text(HTML)] () PDF (203KB) ( 756 )   The separation of four proteins including RNase A, cytochrome C, lysozyme and myoglobin was investigated by reversed-phase gradient pressurized capillary electrochromatography (p-CEC) with 1.5 μm non-porous silica C18 stationary phase. This mode was compared with micro-high performance liquid chromatography (μ-HPLC) and the effects of applied voltage, stationary phase and concentration of ion-pairing agent (trifluoroacetic acid, TFA) on the gradient p-CEC were also studied. This separation was performed rapidly on a new CEC instrument TrisepTM 2010 GV. The results showed that the retention mechanism of proteins in p-CEC mode is based on both chromatographic partitioning and electrophoretic migration. The results also demonstrated that p-CEC may have great potential for fast and efficient separation of proteins.

Select

Investigation on Interactions of Rutin and Chloramphenicol with β-Cyclodextrin Using Capillary Electrophoresis FU Chonggang, YANG Dongzhi 2005, 23 (6):  673-676.  Abstract ( 2020 )   [Full Text(HTML)] () PDF (201KB) ( 659 )   The interactions of two medicines of rutin and chloramphenicol with β-cyclodextrin were investigated using mobility shift method by capillary electrophoresis. The size of the capillary column was 37 cm×50 μm i.d. with an effective length of 30 cm. The running buffer was a mixture of 25 mmol/L sodium borate and 100 mmol/L boric acid (pH 8.6). Effective mobilities of the two medicines changed with altering the concentration of β-cyclodextrin. By nonlinear least square fitting curve, the inclusion constants of 98.5 and 1204 L/mol for rutin and chloramphenicol were obtained at 25 ℃, respectively. The inclusion constants at different temperatures were determined, from which a series of thermodynamic parameters were derived. Experimental results show that an obvious relationship of mutual compensation between enthalpy and entropy existed in these inclusion reactions. The most stable configurations of the inclusions were calculated using MM2 force field, and the results were well in agreement with the experimental results.

Select

Application of High Performance Anion Exchange Chromatography for Trace Analysis of Polarizable Anions MO Shumin, LIANG Lina, CAI Yaqi, MOU Shifen, WEN Meijuan 2005, 23 (6):  677-680.  Abstract ( 2358 )   [Full Text(HTML)] () PDF (178KB) ( 774 )   Polarizable anions such as Br-, S2O2-3, I- and SCN- were separated using 45 mmol/L sodium hydroxide solution as the mobile phase on a high hydrophilic IonPac AS16 column. With a pulsed amperometric detector, the detection limits were 0.5, 0.2, 0.05 and 2 μg/L (25.0 μL injected, signal-to-noise ratio of 3) for Br-, S2O2-3, I- and SCN-. The relative standard deviation (RSD) range of trace anions was from 0.8% to 3.7% (n=9). Under the same chromatographic conditions, these anions were also determined using a suppressed conductivity detector and the detection limits were 1, 1, 2 and 10 μg/L (25 μL injected, signal-to-noise ratio of 3), respectively. The RSD range was from 0.9% to 4.7% (n=9). Comparing a pulsed amperometric detector with a conductivity detector, the former is 2 to 40 times more sensitive than the latter. For the determination of polarizable anions, a pulsed amperometric detector has higher selectivity, precision and sensitivity.