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Chinese Journal of Chromatography
2006, Vol. 24, No. 6
Online: 30 November 2006

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Strategy of Quality Control for Traditional Chinese Medicines and Chromatographic Technology LI Famei, XIONG Zhili, LU Xiumei, QIN Feng, LI Xiaoqin 2006, 24 (6):  537-544.  Abstract ( 2935 )   [Full Text(HTML)] () PDF (316KB) ( 1723 )   The application of chromatography, a modern technology for highly efficient separation and analysis in the research of therapeutic basis matter and quality control of traditional chinese medicine (TCM), is summarized. A new strategy with metabonomics is put forward to achieve integral study on therapeutic basis matter and action mechanism of TCM, and to reveal and control the comprehensive quality of TCM. Modern chromatography and hyphenated techniques are one of the important technique platforms in quality control of TCM.

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Application of Liposomes in Liquid Chromatography and Capillary Electrophoresis QU Feng, DENG Yulin, ZHANG Yukui 2006, 24 (6):  545-550.  Abstract ( 2223 )   [Full Text(HTML)] () PDF (172KB) ( 810 )   Liposome has similar lipid bilayer structure and fluid characteristics to real cell membrane, and plays an important role in mimetic biomembrane research. The preparation and characterization of liposome, studies on drug-liposome partitioning and protein-liposome interaction with immobilized liposome chromatography, application of liposome on drug separation, protein separation and protein interaction by capillary electrophoresis are reviewed.

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Application of Molecularly Imprinted Solid Phase Extraction in the Assay of Environmental Samples MENG Zihui, ZHANG Qiuyue, CHEN Xiaoping, ZHOU Zhiming, WU Yukai, WEN Hongliang 2006, 24 (6):  551-554.  Abstract ( 2557 )   [Full Text(HTML)] () PDF (124KB) ( 1754 )   Molecularly imprinted polymers (MIPs) have already appeared as new selective sorbents for solid phase extraction (SPE) of organic compounds in different samples by extracting certain analytes selectively from complex matrices without matrix interference. This review aims to present a summary of the application of MIPs in the solid phase extraction and enrichment of analytes from the environmental samples. The target analytes include pesticides, herbicides, toxins, veterinary drugs, heavy metal ions, endocrine disruptor compounds and other environmental hazards.

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Enrichment of Nicotine in Plasma with Three-Phase Hollow Fiber Based Liquid Phase Microextraction YANG Xinlei, LUO Mingbiao, TANG Yuping 2006, 24 (6):  555-559.  Abstract ( 2443 )   [Full Text(HTML)] () PDF (1291KB) ( 1015 )   A novel method for fast determination of nicotine in plasma was established by using high performance liquid chromatography (HPLC) coupled with a three-phase hollow fiber based liquid phase microextraction (TP-HF-LPME) technique for sample preparation. The microextraction was mediated by the pH difference between the environment inside and outside of an organic phase immobilized in the pores formed in the wall of a polypropylene hollow fiber. The pH value of the medium outside the organic phase was adjusted by adding a dilute KOH solution to form a basic donor phase while the pH value of the inner media was set to pH 3 to form an acceptor phase using a 10 mmol/L KH2PO4 solution. On working conditions, neutral nicotine molecules were firstly extracted from the original sample solution to the organic phase, and then the analyte was extracted from the organic phase to the acceptor phase. After described extraction time, 4 μL of acceptor phase was withdrawn and directly injected into HPLC system for analysis. Parameters related to TP-HF-LPME (organic solvent, pH of acceptor and donor phase, stirring rate, salt effect, methanol content in acceptor phase and extraction time) were also optimized experimentally. The proposed method integrates extraction, enrichment and clean-up into a single step, dramatically simplifying the traditional procedure to prepare a liquid sample with complex matrices such as plasma. It has been demonstrated to be a very fast, effective and virtually "green" sample preparation technique, which provided a good linear range (0.1-50 mg/L) with r2 of 0.9996, a low detection limit (0.05 mg/L, S/N= 3) and a satisfactory relative standard deviation (<5%).

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Study on the Retention Behaviors and Analytical Methods of Polysaccharides from Duanaliella salina by High Performance Size-Exclusion Chromatography DAI Jun, YIN Hongping, CHEN Shangwei, ZHU Song, GU Xiaohong, WANG Min, TANG Jian, 2006, 24 (6):  560-565.  Abstract ( 2268 )   [Full Text(HTML)] () PDF (515KB) ( 828 )   There are many polysaccharides with biological activities including anti-virus and anti-tumor in the residue produced by the extraction of β-carotene from Duanaliella salina. In this paper, a method of high performance size-exclusion chromatography coupled with refractive index detection has been developed for the relative molecular mass analysis of the polysaccharides isolated from the residue. The effects of salt and pH values of mobile phase on retention behaviors of five polysaccharides fractions were investigated on two HPSEC columns (Waters Ultrahydragel Linear, 7.8 mm i.d.×300 mm) connected in series. The results showed that 0.1 mol/L NaAc buffer solution may be utilized as mobile phase during HPSEC under the conditions of column temperature of 45 ℃ and flow rate of 0.9 mL/min to minimize nonspecific interaction of sulfated polysaccharides fraction (PD4a), complex carbohydrate containing oligonucleic acid (PD4b) and acidic polysaccharide fraction (PD1) with the column matrix. In addition, under the conditions the association effect of the polysaccharide molecules was eliminated. Thereby, the polysaccharide molecules were eluted and separated following equilibrium exclusion mechanism mainly. The weight mean molecular masses (Mw) of five polysaccharide fractions from D.salina determined under optimum chromatographic conditions were 1548000 for PD1, 33000 for PD2, 67000 for PD3, 424000 for PD4a and 10000 for PD4b. For sulfated polysaccharide fraction PD4a, the relative standard deviations were 1.7% and 0.88% for Mw and peak area, respectively.

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Determination of Chlorhexidine Acetate in Chlorhexidine Acetate Suppositories by High Performance Liquid Chromatography Coupled with Hollow Fiber Membrane Solvent Microextraction FU Huafeng, GUAN Jiyu, QU Zhishuang, BAO Jianmin 2006, 24 (6):  566-569.  Abstract ( 2124 )   [Full Text(HTML)] () PDF (526KB) ( 880 )   A novel method was developed to determine the content of chlorhexidine acetate (CA) in chlorhexidine acetate suppositories by high performance liquid chromatography （HPLC） coupled with hollow fiber membrane solvent microextraction. The sample was extracted with 1.5 mol/L acetic acid solution five times, then a hollow fiber containing n-octanol was placed in the sample solution to perform microextraction for extracting 20 min. The extract was analyzed by HPLC with UV detection at 260 nm. The chromatographic conditions were as following: acetonitrile-redistilled water (29∶71, v/v, containing 0.3% triethylamine, pH 3.0) as mobile phase with the flow rate of 1 mL/min. The calibration curve of CA was linear from 0.5 to 16 mg/L. The method recovery was over 98.0% with relative standard deviation less than 4.0%. By using hollow fiber membrane solvent microextraction, the enrichment of 24-fold was achieved. The method is specific, simple, fast, sensitive and suitable for the determination of chlorhexidine acetate.

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Separation of Isomeric Compounds by High Speed Countercurrent Chromatography CHEN Li, DENG Lijie, CHEN Ping 2006, 24 (6):  570-573.  Abstract ( 2478 )   [Full Text(HTML)] () PDF (373KB) ( 1015 )   High speed countercurrent chromatography (HSCCC) was successfully used for the separation and preparation of isomeric compounds. The influence of various two-phase solvent systems on the resolution of the natural catechin isomers of (-)-epigallocatechin gallate (EGCG) and (-)-gallocatechin gallate (GCG) from green tea polyphenols and the synthetic isomeric compounds of para-, ortho-, meta-bromoanilline was investigated. The results indicated that the catechin isomers of (-)-EGCG and (-)-GCG can be isolated through two runs of preparative HSCCC with two-phase solvent system composed of n-hexane-ethyl acetate-water (1∶10∶10 in volume ratio). The upper organic phase was used as stationary phase and the lower aqueous phase as mobile phase, while the mobile phase was operated at a flow rate of 3.5 mL/min, and the apparatus rotated at 800 r/min. High performance liquid chromatographic analysis of (-)-EGCG and (-)-GCG revealed that the purity was all over 98%. The isomeric compounds of para-, ortho-, meta-bromoaniline can also be effectively isolated through a single run of preparative HSCCC with the mobile phase flow rate of 3.0 mL/min and the apparatus rotation speed of 800 r/min by using tetrachloromethane-chloroform-methanol-water (7∶3∶7∶3 in volume ratio) as two-phase solvent system, while the lower phase was selected as stationary phase and the upper phase as mobile phase.

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Resolution of Racemic 1,1′-Bi-2-Naphthol and Its Derivatives by Molecularly Imprinted Polymers LI Lihong, LIU Lan, LUO Yong, DENG Qinying 2006, 24 (6):  574-577.  Abstract ( 2600 )   [Full Text(HTML)] () PDF (274KB) ( 2492 )   1,1′-Bi-2-naphthol is one of the most popular analytes in chiral separation since optically active 1,1′-bi-2-naphthol and its derivatives are frequently used as chiral auxiliaries and ligands in asymmetric synthesis. Therefore, it was employed as template for the preparation of molecularly imprinted polymer (MIP) which was used as liquid chromatographic stationary phase. In this study, the MIP was prepared by bulk polymerization using (R)-(+)-1,1′-bi-2-naphthol as template molecule, 4-vinyl pyridine, ethylene glycol dimethacrylate and acetonitrile as functional monomer, cross-linker and porogen respectively. High performance liquid chromatography (HPLC) was employed to study the chiral recognition properties of the resulting MIP. The effect of chromatographic conditions, such as the composition of mobile phase, flow rate and column temperature, on the enantioseparation were systematically investigated. It was experimentally shown that the MIP had specific interactions and high affinity with the template molecule. The MIP could effectively resolve the rac-1,1′-bi-2-naphthol, and the separation factor was found to be 12.25 under the following conditions: mobile phase, acetonitrile-acetic acid (99∶1, v/v); flow rate, 1.2 mL/min; column temperature, 30 ℃. The addition of acetic acid to the mobile phase can improve the peak shape, and the lower flow rate and lower column temperature is better for the separation. Further, other substrates which have the similar structure with 1,1′-bi-2-naphthol , i.e, 5,6,7,8,5′,6′,7′,8′-octahydro-1,1′-bi-2-naphthol and 1,1′-binaphthalenyl-2-amino-2′-ol were also resolved partly by optimizing the HPLC conditions, with separation factors of 1.51 and 2.40, respectively.

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Separation and Purification of 2-Chloro-5-Trichloromethylpyridine from Products of Photochemical Chlorination of 3-Methylpyridine Using Preparative Liquid Chromatography SU Li, ZHANG Yong, HUANG Keming 2006, 24 (6):  578-580.  Abstract ( 1967 )   [Full Text(HTML)] () PDF (253KB) ( 731 )   A preparative high performance liquid chromatographic technique was used to separate and purify 2-chloro-5-trichloromethylpyridine from the products of photochemical chlorination with 3-methylpyridine as raw material. The elution mode, the flow rate of the mobile phase and injection volume were optimized. The optimum operation parameters were selected as follows: Zorbox-C18 reversed-phase column with the flow rate gradient elution of 30% acetonitrile in water as the mobile phase (gradient elution program: 0-8 min at 4 mL/min, 8-14 min at 10 mL/min), and a diode array detector with wavelength set at 240 nm, injecting volume of 100 μL. The average recovery rate was 82.7% and relative standard deviation (RSD) was 4.0%（n=5）. High purity (99.01%) product was obtained. The effective and accurate method has been successfully applied to the preparation of pure 2-chloro-5-trichloromethylpyridine.

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Simultaneous Determination of Aflatoxins, Zearalenone and Ochratoxin A in Cereal Grains by Immunoaffinity Column and High Performance Liquid Chromatography Coupled with Post-Column Photochemical Derivatization LI Jun, YU Yimang, TIAN Miao, WANG Hongwei, WEI Feng, LI Li, WANG Xiong 2006, 24 (6):  581-584.  Abstract ( 2770 )   [Full Text(HTML)] () PDF (944KB) ( 1960 )   A method was developed for the simultaneous determination of aflatoxins (AFs) (B1, B2, G1 and G2), zearalenone (ZEA) and ochratoxin A (OTA) in cereal grains by high performance liquid chromatography （HPLC） with fluorescence detection after immunoaffinity column clean-up and post-column derivatization. Cereal grain sample was extracted with methanol-water (80∶20, v/v). The extract was purified by immunoaffinity column and the toxins were separated by reversed-phase HPLC, and quantified with fluorescence detection after photochemical derivatization. The separation was performed on a Nova-Pak column (3.9 mm i.d.×150 mm, 4 μm, Waters) with a linear gradient of methanol-acetonitrile-1%phosphoric acid mixture. The calibration curves for mycotoxins were made in the concentration range of 0.24-6.0 for AFs (B1,B2,G1 and G2), 4.0-100.0 for ZEA and 0.5-40.0 μg/L for OTA. Recoveries of the different cereal grains (wheat, rice, rye) spiked with mycotoxins at levels ranged from 0.24-1.0 μg/kg for AFs (B1, B2, G1 and G2), 4.0-16.0 μg/kg for ZEA and 0.5-3.0 μg/kg for OTA were from 70.8% to 94.0% and relative standard deviations were between 2.79% and 9.38%. The limits of detection were 0.24 μg/kg for AFs (B1, B2, G1 and G2), 0.5 μg/kg for OTA and 4.0 μg/kg for ZEA.

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Simultaneous Determination of Residues of 12 Amide Herbicides in Soybeans by High Performance Liquid Chromatography LI Jianzhong, CHU Xiaogang, CAI Huixia, AN Juan, YANG Qiang 2006, 24 (6):  585-588.  Abstract ( 2139 )   [Full Text(HTML)] () PDF (222KB) ( 881 )   An analytical method was developed for the simultaneous determination of 12 amide herbicide residues in soybeans. The 12 amide herbicides were extracted with acetone from soybean samples. The extract was cleaned up using a Florisil cartridge, and then determined by high performance liquid chromatography. Kromasil 100-5C18 column (4. 6 mm i.d.×250 mm, 5 μm) as analytical column, pure water-acetonitrile as mobile phase with a flow rate of 1.0 mL/min and gradient elution, and a diode array detector set at 210 nm were used. The recoveries of amide herbicides from soybeans spiked at levels of 0.05, 0.1 and 1.0 mg/kg were in the range of 75%-102% with relative standard deviations of 1.9%-16.1%. The method has good linear in the range of 0.05-1.0 mg/L for each analyte (r＞0.999). The detection limit for each amide herbicide was less than 0.05 mg/kg. The method is simple, rapid and accurate. It can be used for the inspection of amide herbicide residues in soybeans.

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Simultaneous Determination of Inhibitive Components in Anti-Acne Cosmetics by Reversed-Phase High Performance Liquid Chromatography WU Ting, WANG Chao, LI Nan 2006, 24 (6):  589-591.  Abstract ( 2166 )   [Full Text(HTML)] () PDF (180KB) ( 982 )   The inhibitive components in anti-acne cosmetics including spironolactone, benzoyl peroxide, and tretinoin were simultaneously determined by reversed-phase high performance liquid chromatography (RP-HPLC). The cosmetics were extracted with methanol by microwave and analyzed by high performance liquid chromatography. The HPLC conditions were as follows: Kromasil C18 column (4.6 mm i.d.×250 mm, 5 μm), methanol and phosphate buffer as mobile phase with gradient elution at a flow rate of 1.0 mL/min, UV detection at 265 nm. Three components were separated completely within 11 min. The calibration curves of the three compounds were linear (r>0.9999) between 1 and 200 mg/L. The average recoveries were from 88.2% to 106.7% with relative standard deviations lower than 3.1%. The detection limits (S/N=3) were 0.101 μg for spironolactone, 0.100 μg for benzoyl peroxide, and 0.107 μg for tretinoin. The method is simple and rapid with high accuracy, and suitable for the determination of the 3 inhibitive components in anti-acne cosmetics.

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Simultaneous Analysis of Theaflavins and Catechins by Capillary Electrophoresis XIA Wenjuan, ZHANG Lixia, WANG Riwei, SHI Zuoan, JIA Ming 2006, 24 (6):  592-596.  Abstract ( 2618 )   [Full Text(HTML)] () PDF (470KB) ( 719 )   In order to monitor the changes of theaflavins and catechins during the process of tea polyphenol oxidation, a rapid, accurate, sensitive and convenient analytical method was established. The optimum analytical conditions for simultaneous analysis of four theaflavins （TFs） and six catechins by capillary electrophoresis were investigated. The electrolyte solution consisted of 200 mmol/L boric acid (pH 7.7), 10 mmol/L potassium dihydrogenphosphate, 9 mmol/L β-cyclodextrin and 27.5% acetonitrile. The experimental conditions of the instrument were selected as follows: voltage 25 kV, column temperature 30 ℃, and detection wavelength 200 nm. Ten constituents could be separated from each other completely within 8 min and each one had a good linear relationship between its peak area and corresponding concentration (r=0.9907-0.9998). Furthermore, their detection limits were from 0.39 to 0.88 μg/mL, the mean recoveries varied from 91.5%to 113.5%. The relative standard deviations were less than 5%. All the above results showed that the developed method is especially suitable for the analysis of theaflavins and catechins.

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Separation of Phthalates in Non-Aqueous Micelle Using Capillary Electrokinetic Chromatography HUANG Rui, MU Xiaojing, YIN Yongguang, WEI Weili, CHEN Zhitao, XIA Zhining 2006, 24 (6):  597-600.  Abstract ( 2650 )   [Full Text(HTML)] () PDF (170KB) ( 764 )   On the basis of non-aqueous capillary electrophoresis (NACE) and micellar electrokinetic chromatography (MEKC), a novel technique, non-aqueous micellar electrokinetic chromatography (NAMEKC), has been established. NAMEKC has the advantages of NACE and uses the separation mechanism of MEKC, showing special advantages for separation of hydrophobic compounds. Separation of three of the priority pollutants by U.S. Environmental Protection Agency (EPA), i.e. dimethyl phthalate (DMP), diethyl phthalate (DEP), and dibutyl phthalate (DBP), were realized in 15 min. Important factors on separation, such as the amount of water added in the electrophoretic running buffer, the acidity of water phase, the organic additive, and the concentration of sodium dodecyl sulfate (SDS), were investigated. The proportion of water in the electrophoretic running buffer could affect the current and the stability of SDS micelle. Organic additives and the acidity of water phase showed no effect on increasing resolution. The concentration of SDS was a dominant factor, affecting the partition of analytes in micelle. DMP, DEP, and DBP were separated in a short time under the optimized operation conditions using 20 mmol/L NaH2PO4 and 120 mmol/L SDS in formamide/water (9/1, v/v). The application of NAMEKC leads to successful separation of the three typical hydrophobic compounds, which provides a novel means to separate and analyze hydrophobic compounds.

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Analysis of Chemical Components in Tobacco Flavors Using Stir Bar Sorptive Extraction and Thermal Desorption Coupled with Gas Chromatography-Mass Spectrometry HOU Ying, YANG Lei, WANG Baoxing, XU Jicang, YANG Yong, YANG Yan, CAO Qiue, XIE Xiaoguang 2006, 24 (6):  601-605.  Abstract ( 2397 )   [Full Text(HTML)] () PDF (318KB) ( 897 )   A novel method for the analysis of chemical components in tobacco flavors was established using stir bar sorptive extraction (SBSE) and thermal desorption coupled with gas chromatography-mass spectrometry (GC-MS). The different parameters affecting the extraction of the analytes from the samples to the poly(dimethylsiloxane)(PDMS) coated stir bars and the conditions affected thermal desorption were investigated. The optimized extraction conditions were that the sample was extracted with a stir bar (10 mm length and 0.5 mm thickness) at 1100 r/min for 1 h at ambient temperature. Desorption was carried out from 20 ℃ ramped to 250 ℃ at 60 ℃/min and hold for 2 min under a helium flow of 50 mL/min in the splitless mode while maintained the cryofocusing temperature of -100 ℃ in a CIS-4 injector of the GC-MS system. Finally, the CIS-4 injector was raised to a temperature of 280 ℃ and the analytes were separated by GC and detected by MS using full scan mode (m/z 35-400). Under the described conditions, about 30 components were identified from the tobacco flavors, and the major components included esters, ketones, aldehydes, etc. The average relative standard deviation (RSD) of peak areas of 30 components for 6 determinations was less than 10%. The good repeatability made SBSE a powerful tool for the routine quality control analysis of chemical components in tobacco flavors.

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Study of Pyrolysates of Flue-Cured Tobacco Leaves and Stems YANG Weizu, XIE Gang, WANG Baoxing, HOU Ying, XU Jicang, YANG Yong, YANG Yan, WANG Yu 2006, 24 (6):  606-610.  Abstract ( 2497 )   [Full Text(HTML)] () PDF (230KB) ( 947 )   To further understand the effect of tobacco stems in tobacco blend, a detailed comparative study of chemical components of tobacco leaves and stems before and after combustion was carried out. Pyrolysis of tobacco leaves and stems was carried out by a CDS Pyrolyser 2000 coupled to a Finnigan 8000TOP Gas Chromatograph and a Voyager Mass Spectrometer (GC-MS). A modified apparatus of pyrolysis was used to emulate the behavior of combustion of cigarette. A set of pyrolysis conditions was also developed that approximated those occurring in the pyrolysis region of the burning cigarette. The conditions included heating the sample at 20 ℃/ms from 30 ℃ to 300 ℃, 600 ℃ and 900 ℃ in air, and their pyrolysates were analyzed by GC-MS. The results indicated that the values of routine chemical constituents in tobacco leaves and stems were obviously different. The pyrolysates belonged to numerous classes of compounds such as hydrocarbons, alcohols, phenols, aldehydes, ketones, nitriles, alkaloids etc. The kinds of pyrolysates of tobacco leaves and stems were positively related to the pyrolysis temperature levels. On the other hand, at the same temperature level, the types of the pyrolysates from the tobacco leaves were much more than those from the tobacco stems.

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Study of Pyrolysates of β-Carotene in Tobacco YANG Weizu, XIE Gang, WANG Baoxing, HOU Ying, YANG Yong, XU Jicang, YANG Yan, WANG Yu 2006, 24 (6):  611-614.  Abstract ( 2737 )   [Full Text(HTML)] () PDF (725KB) ( 964 )   Relationships between tobacco compounds and smoke products are complex and often difficult to unravel. Pyrolysis experiments have frequently been used to establish such relationships. The relevance of pyrolysis experiments to the behavior of tobacco constituent in a burning cigarette was studied. A set of pyrolysis conditions has been developed to study the effect of thermal degradation of β-carotene to the cigarette smoke quality, and the conditions was approximated to those occurring in the pyrolysis region of the burning cigarette. The pyrolysates of β-carotene were investigated in air, 10% O2 (in N2) and N2 at three temperature levels of 300 ℃, 600 ℃ and 900 ℃, respectively. The pyrolysates were adsorbed by solid-phase microextraction (SPME) and then analyzed by gas chromatography/mass spectrometry (GC/MS). Under the different conditions, the major pyrolysates from β-carotene are hydrocarbon compounds such as toluene, p-xylene, 1,2,3,4-tetrahydro-1,1,6-trimethyl-naphthalene and 2,7-dimethyl-naphthalene, and some important flavors existing in cigarette smoke such as isophorone, 2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde, β-ionone and 5,6,7,7a-tetrahydro-4,4,7a-trimethyl-2 (4H)-benzofuranone. The amount of these pyrolysates alters with the change of pyrolysis temperature levels and the concentration of oxygen.

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Analysis of C9 Fraction of Pyrolysis Gasoline by Gas Chromato-graphy and Gas Chromatography/Mass Spectrometry WANG Hua, LIU Wenmin, XU Yuan, GUAN Yafeng 2006, 24 (6):  615-618.  Abstract ( 3142 )   [Full Text(HTML)] () PDF (263KB) ( 822 )   The constituents of C9 fraction of pyrolysis gasoline were analyzed by gas chromatography (GC) with flame ionization detector (FID) and gas chromatography/mass spectrometry (GC/MS). A 100 m×0.25 mm i.d.×0.5 μm PONA column was used to improve the separation efficiency and sample load compared with the standard PONA column of 50 m ×0.20 mm i.d. Identifications of compounds were based on the standards of n-alkanes and a few aromatics, high accuracy retention time simulation and live retention time database, and cross-references with MS data. The search in live retention time database gives a few possible compounds that were co-eluting or adjacent from each other. While the MS search results for each peak always report 10 or even more compounds who has similar fragments. The cross-reference of the above method yields much more reliable identification results than normal GC/MS search. Quantitative analysis of each compound and the carbon number distribution were performed by GC with FID. Thirty-nine compounds with contents more than 0.2% in the C9 fraction were identified. The relative standard deviation of quantitative analysis was below 5%. It provides a reliable method for detailed analysis of C9 fraction.

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Comparison of Chemical Components of Essential Oils in Needles of Pinus massoniana Lamb and Pinus elliottottii Engelm from Guangxi SHEN Changmao, DUAN Wengui, CEN Bo, TAN Jianhui 2006, 24 (6):  619-624.  Abstract ( 2389 )   [Full Text(HTML)] () PDF (701KB) ( 816 )   Essential oils were extracted by steam distillation from the needles of Pinus massoniana Lamb and Pinus elliottottii Engelm grown in Guangxi. Various factors such as pine needle dosage and extraction time which may influence the oil yield were investigated. The optimum conditions were found to be as follows: pine needle dosage 700 g, extraction time 5 h. The essential oil yields from the needles of Pinus massoniana Lamb and Pinus elliottottii Engelm were 0.45% and 0.19%, respectively. Moreover, the chemical compositions of the essential oils were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Sixty four components in the essential oil from needle of Pinus massoniana Lamb were separated and twenty of them (98.59%) were identified while seventy three components in the essential oil from needle of Pinus elliottottii Engelm were separated and twenty nine of them (94.23%) were identified. Generally, the compositions of the essential oils from needles of the two varieties were similar but the contents of some compounds differed greatly. Especially, the content of α-pinene in the essential oils from Pinus massoniana Lamb needles was 2.6 times as that from Pinus elliottottii Engelm needles, but the content of β-pinene was less than the latter. Mono- and sesquiterpenes were the main composition of the essential oils from Pinus massoniana Lamb and Pinus elliottottii Engelm needles.

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Determination of Acrylamide in Foods by Gas Chromatography-Mass Spectrometry SHEN Weijian, SHEN Chongyu, ZHAO Zengyun, CHEN Huilan, XU Jinzhong 2006, 24 (6):  625-628.  Abstract ( 2397 )   [Full Text(HTML)] () PDF (280KB) ( 861 )   A confirmatory method is presented for the determination of acrylamide in different food products by gas chromatography-mass spectrometry (GC-MS). The method is based on the extraction of acrylamide with water and methanol, and purification with Carrez Ⅰ(zinc sulfate) and Carrez Ⅱ (potassium hexacyanoferrate) solution, followed by bromination onto the acrylamide double bond. The derivative was extracted with ethyl acetate/hexane (4∶1, v/v), and converted to the stable 2-bromopropenamide by dehydrobromination using 10% triethylamine, then analyzed by GC-MS, employing 13C3-acrylamide as internal standard. In-house validation data for flour and bread showed good accuracy and precision of the method. The recoveries of acrylamide in the French fries and bread were all in the range from 80% to 110% after correction of analyte loss by the internal standard at three spike levels of 0.02, 0.05 and 0.2 mg/kg, and relative standard deviations (RSDs) no more than 12.7%. The limits of detection for flour and bread were estimated at 5 μg/kg.

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Determination of 25 Organochlorine Pesticides in Tea by Gas Chromatography-Mass Spectrometry ZHAO Qionghui, JIN Baohui, XIE Liqi, WU Weidong, LAN Fang, LIN Li, HAN Ruiyang 2006, 24 (6):  629-632.  Abstract ( 2155 )   [Full Text(HTML)] () PDF (336KB) ( 931 )   A high performance gas chromatography-mass spectrometry (GC-MS) method for the determination of 25 organochlorine pesticides in tea has been developed. The samples of tea were extracted with n-hexane-acetone (2∶1, v/v). The extract was purified by using a Florisil column with n-hexane-ethyl acetate (9∶1,v/v) as elution solvent. Chromatographic analysis was performed on a DB-35MS capillary column. Satisfactory separation and sensitivity of 25 organochlorine pesticides were obtained with the proposed method. The analytical results show the working curves for 25 organochlorine pesticides were linear in the range of 0.010-0.500 mg/L by GC-MS on selective ion monitoring mode. The recoveries of 25 organochlorine pesticides at spiked levels of 0.01-0.20 mg/kg were 70.8%-105.5%, and relative standard deviations (RSDs) were 1.6%-12.7%. The limits of quantitation were 0.01 mg/kg except that for endosulfanⅠand endosulfanⅡthat were 0.02 mg/kg.

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Determination of Imidacloprid Residues in Vegetable and Tea Samples Using Liquid Chromatography-Mass Spectrometry/Mass Spectrometry XIE Wen, DING Huiying, JIANG Xiaoying, XI Junyang 2006, 24 (6):  633-635.  Abstract ( 2192 )   [Full Text(HTML)] () PDF (187KB) ( 1300 )   A liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) method was developed for the determination of imidacloprid in vegetable and tea samples. The sample was first extracted with acetonitrile and then cleaned up with Florisil and active charcoal column. The precursor ion/product ion transitions m/z 256.0/209.3 and m/z 256.0/175.2 were monitored, and m/z 209.3 was used for quantification. The good linearity was obtained in the range of 0.01-0.5 mg/L with the correlation coefficients (r2) more than 0.997. The limit of quantification was 0.01 mg/kg. The recoveries were 76%-90% at the spiked levels of 0.01,0.05 and 0.2 mg/kg with the relative standard deviations of 7.4%-11.0%. The method is rapid, sensitive and specific for imidacloprid analysis.

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Simultaneous Determination of Residues of Organochlorine and Pyrethroid Pesticides in Tea by Microwave Assisted Extraction Solid Phase Microextraction-Gas Chromatography YUAN Ning, YU Binbin, ZHANG Maosheng, ZENG Jingbin, CHEN Xi, 2006, 24 (6):  636-640.  Abstract ( 2520 )   [Full Text(HTML)] () PDF (229KB) ( 1161 )   The issue of residues including organochlorine and pyrethroid pesticides in tea has made a great attention of researchers and customers in the world. Although some analytical methods have well been established to detect these pesticides, the sample preparations are generally laborious, time-consuming, and some of the procedures caused environmental pollution. Solid phase microextraction (SPME) is a novel sample preparation technique since it is of simplicity, high efficiency and solvent free. SPME was firstly developed to address the need to facilitate environment monitoring. In recent years, great efforts have been made in the analysis of pesticide residues in agricultural products by SPME. In this research, a microwave assisted extraction solid phase microextraction-gas chromatography (MAE-SPME-GC) was applied for the simultaneous determination of organochlorine and pyrethroid pesticides, such as benzene hexa chlorides (α-BHC, β-BHC, γ-BHC and δ-BHC), 1-(2-chlorophenyl)-1-(4-chlorophenyl)-2,2,2-trichloroethane (o,p′-DDT), 2,2-bis (4-chlorophenyl)-1,1-dichloroethylene (DDE), 2,2-bis (4-chlorophenyl)-1,1-dichloroethane (DDD), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1,1-trichloroethane (p,p′-DDT), cypermethrin and fenvalerate. All the tested pesticides were baseline separated under the experimental conditions, except for DDD and o,p′-DDT. The concentration of each pesticide was calibrated by external standard method. The linearities were found to be in the correlation coefficient range of 0.9705 to 0.9984 for the tested pesticides between the mass concentrations and peak areas, except for fenvalerate. The recoveries, relative standard deviations and detection limits for the 10 pesticides were 64%-121%, 10.4%-22.9%, and 1-50 ng/L, respectively. The proposed method was successfully applied to the determination of organochlorine pesticide residues in three kinds of teas from the local market. The experimental results demonstrated that MAE-SPME-GC was a fast, sensitive and green technique for the analysis of trace quantity of pesticides in solid substrate foods.

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Hollow Fiber Liquid Phase Microextraction of Tramadol from Water and Biological Samples WANG Xiaofei, LIU Junting, WANG Yan, ZHAO Xiuli, GAO Lina, XU Donghui 2006, 24 (6):  641-644.  Abstract ( 2297 )   [Full Text(HTML)] () PDF (314KB) ( 797 )   A novel technique of liquid phase microextraction supported by hollow fiber membrane (LPME-HFM) was applied to extract tramadol in tap water, urine and human plasma. At room temperature (20 ℃), polyvinylidene fluoride hollow fiber membrane (PVDF-HFM) was employed. In the procedure of extraction, 4 μL of organic solvent (toluene) was used in individual extraction. Pethidine was used as the internal standard (IS) in the sample analysis by gas chromatography with flame ionization detector (GC-FID). The optimized conditions for tramadol extraction was as follows: toluene as organic solvent, 4 mL sample solution added with 0.1 mL of 1 mol/L NaOH solution, extraction time of 15 min, and stirring speed of 300 r/min. The sample solutions, containing a series of concentrations of tramadol, 0.05, 0.10, 0.50, 1.0, 5.0, 10.0 mg/L, were analyzed. The good linearities were obtained for water, human urine and human plasma samples with the correlation coefficients of 0.9997, 0.9948 and 0.9985, respectively. The detection limits can reach 0.01 mg/L for water and human urine and 0.05 mg/L for human plasma. The relative standard deviations (RSDs) were 10.6% and 5.15% for water, 18.1% and 4.03% for urine solution at the spiked levels of 0.1 and 1.0 mg/L. The RSDs were 16.6% and 4.15% for plasma solution at the spiked levels of 0.5 and 1.0 mg/L. In comparison with conventional method, this method is simple, sensitive, fast, inexpensive, and environmentally friendly. It can be applied to pharmaceutical and forensic analysis.

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Analysis of cis-9, trans-11-Conjugated Linoleic Acid in Milk Fat by Capillary Gas Chromatography WANG Xiaojing, SHEN Xiangzhen, HAN Hangru, ZHAO Ruqian, CHEN Jie 2006, 24 (6):  645-647.  Abstract ( 2234 )   [Full Text(HTML)] () PDF (189KB) ( 799 )   Conjugated linoleic acid (CLA) is a term representing a mixture of positional and geometric isomers of octadecadienoic acid with a conjugated double bond system. Conjugated linoleic acid has attracted a great deal of interest among nutritionists because it is a natural fat component that appears to have a number of health improvement properties. The cis-9, trans-11-CLA is the major CLA isomer found in dairy products accounting for 75% to 90% of the total CLA in milk fat. A capillary gas chromatographic method equipped with a flame ionization detector for the analysis of the cis-9, trans-11-CLA in milk fat was developed. The cis-9, trans-11-CLA was extracted with hexane-isopropanol,methylated with methanol-sodium methylate and cis-9,trans-11-CLA was separated and quantified using gas chromatography. Retention time of the peaks was used for qualitative analysis, while external standard method was used for quantitative analysis. The recovery of the cis-9, trans-11-CLA was 100.26%. The relative standard deviation was 1.9% (n=6). This method presented is advantageous for high precision, high sensitivity analysis with smaller sample size and simpler pretreatment. It would be of significance for analyzing the contents of other fatty acids in the milk and milk products.

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Simultaneous Determination of Triazine Herbicide Residues in Maize by Gas Chromatography ZHANG Jingbo, JIANG Wenfeng, DONG Zhenlin, ZHAO Shoucheng, WEI Feng 2006, 24 (6):  648-651.  Abstract ( 2226 )   [Full Text(HTML)] () PDF (201KB) ( 1081 )   A gas chromatographic method was developed for the determination of simeton, simazine, atrazine, propazine, terbumeton, terbuthylazine, cyprazine, simetryn, prometryn, terbutryn, methoprotryne, hexazinone residues in maize. The triazine herbicide residues were extracted with acetonitrile by blender and then cleaned up on a strong cation-exchange (SCX) solid-phase extraction cartridge. The SCX cartridge was conditioned with acetone, methylene chloride, washed with methylene chloride, acetone and eluted with methanol-water (9∶1, v/v) solution saturated potassium chloride. As a result, most interfering impurities were removed in the SPE cleanup procedure. The gas chromatographic analysis was performed on a capillary column (DB-5, 30 m×0.25 mm i.d.×0.25 μm) and determined by nitrogen phosphorus detector (NPD). Twelve triazine herbicides were effectively separated on this column. Diazinon was used as the internal standard for the determination. Linear correlation coefficients of the 12 herbicides were higher than 0.998 in the range of 0.01 to 2.0 mg/L. The limits of quantitation of the method were 0.01 mg/kg for these compounds. Average recoveries of these herbicides from spiked samples ranged from 84.0 % to 106.8% at fortification levels of 0.01-0.5 mg/kg and the relative standard deviations (RSDs) were between 0.9% and 4.7%. The method is suitable for the simultaneous determination of a wide range of triazine herbicides in maize in commodities inspection.

技术应用

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Simultaneous Determination of Gallic Acid and Protocatechuic Acid in Choerospondias axillaries by RP-HPLC DENG Kejun， ZHANG Yi， WANG Ping， YANG Zujun 2006, 24 (6):  652-653.  Abstract ( 4049 )   [Full Text(HTML)] () PDF (139KB) ( 956 )

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Simultaneous Determination of Sixteen Hormones in Cosmetics by RP-HPLC WANG Chao, MA Qiang, WANG Xing 2006, 24 (6):  654-655.  Abstract ( 2217 )   [Full Text(HTML)] () PDF (179KB) ( 1215 )

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Determination of Swainsonine by ISC GUO Zhian, ZHANG Xiaohui, ZHAO Jingchan, YUAN Hongan, LIANG Xiaoyun 2006, 24 (6):  656-656.  Abstract ( 1994 )   [Full Text(HTML)] () PDF (75KB) ( 838 )

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Chiral Separation of Citalopram Intermediate Compounds by CE JIANG Junpo, XU Hongmei, CHEN Zhitao, XIAO Shangyou, XIA Zhining 2006, 24 (6):  657-657.  Abstract ( 1938 )   [Full Text(HTML)] () PDF (97KB) ( 724 )

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Improved Enantioseparation of Basic Drugs by CE Using Chemically Bonded Polyethyleneimine Coated Capillary CHEN Zhuoling, DING Guosheng 2006, 24 (6):  658-658.  Abstract ( 2073 )   [Full Text(HTML)] () PDF (87KB) ( 787 )

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Determination of Chloramphenicol in Cosmetics by GC-MS XIE Weiping, CHEN Chunzhu, HUANG Yingyu, FU Huirong 2006, 24 (6):  659-659.  Abstract ( 2375 )   [Full Text(HTML)] () PDF (93KB) ( 898 )

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Study on the Carrier Gas Used in GC-MS Analysis ZHAO Jingchan, GUO Zhian, LIANG Xiaoyun, ZHANG Xiaohui, KANG Chaoguo 2006, 24 (6):  660-660.  Abstract ( 2107 )   [Full Text(HTML)] () PDF (71KB) ( 728 )

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Rapid Determination of Bicarbonate in Mineral Waters by IEC LIU Jingsheng， LIU Xiao, CAI Yaqi， MOU Shifen 2006, 24 (6):  661-661.  Abstract ( 1808 )   [Full Text(HTML)] () PDF (66KB) ( 728 )