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Chinese Journal of Chromatography
2005, Vol. 23, No. 4
Online: 30 July 2005

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研究报告

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Quantitative Structure-Retention Relationships of Monosubstituted Alkanes by Dividing Its Molecular Structure into Substructure CAO Chenzhong, HUO Ping, GAO Shuo, ZHOU Zaichun 2005, 23 (4):  329-335.  Abstract ( 2093 )   [Full Text(HTML)] () PDF (264KB) ( 603 )   In order to investigate the quantitative structure-retention relationship in gas chromatography (GC), the molecular structure of monosubstituted alkane RX (X=halogen, OH, SH, NH2) is divided into two parts, R and X, to obtain molecular structure parameters, and the retention times in GC for 37 monosubstituted alkanes RX were determined. It was proposed that the retention time in GC is affected by three main factors for RX compounds, alkyl group R, substituted group X, and interaction between R and X. Using four parameters, the eigenvalue of bonding orbital-connection matrix EVM, the polarizability effect index of alkyl group PEI, the mass content for substituted group X, and the partial charge ΔNH on hydrogen atom of the group X, a quantitative structure-retention correlation model with correlation coefficient (r) of 0.9948 and standard deviation (S) of 0.0991 was obtained for the 37 RX compounds. The model obtained has good predictive and extrapolation ability. The predicted retention indexes are in good agreement with the experimental ones for alcohols.

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Quantitative Relationship Between Gas Chromatographic Retention Indices and Structural Parameters of LIU Hongyan, WANG Zunyao, LIU Shushen, ZHAI Zhicai 2005, 23 (4):  336-340.  Abstract ( 2116 )   [Full Text(HTML)] () PDF (213KB) ( 609 )   The structural and thermodynamic properties of 76 polychlorinated naphthalenes (PCNs) were fully computed at B3LYP/6-31G* level. Both structural and thermodynamic parameters of PCNs obtained were consequently taken as theoretical descriptors and correlated with their gas chromatographic retention indices (RI), so as to develop the relevant quantitative structure-retention relationship (QSRR) regression model (model Ⅰ) with r2 of 0.9957, which possesses high correlation, high predictive power and clear physical interpretations. Secondly, another linear QSRR model (model Ⅱ) was achieved by employing the number and position of chlorine substitution as descriptors, of which r2 was 0.9967, and also the main factors affecting the retention time of PCNs were investigated.

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Relationships of Surfactant Head Group Weight Fraction and Some Polarity Terms by Gas Chromatography BARAKAT Y, MOSTAFA N E, IBRAHIM V, MANSOUR R 2005, 23 (4):  341-346.  Abstract ( 1883 )   [Full Text(HTML)] () PDF (223KB) ( 439 )   Polarity, partition coefficient (K), methanol carbon number of surfactant ((CMeOH)S), and methanol carbon number of surfactant head group ((CMeOH)HG) are measured on six alkanolamides and five polyoxyethylenated long chain amines as stationary phases. From the measured methanol carbon numbers, polarity indices, (IP)S and (IP)HG, are calculated. The determined polarity terms are plotted against the head group weight fraction ( fHG ) of the investigated surfactants and several equations have been developed. The study reveals that the molecular structural gap between alkanolamides and polyoxyethylenated long chain amines diminished when HLB numbers of these surfactant classes are plotted against fHG values. Consequently, a general equation relating HLB and fHG is obtained.

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Isolation and Identification of Glycinol from Glycine max ［L.］ Merri. QI Yongyan, MOCO Sofia, BOEREN Sjef, de VOS C H Ric, BOVY Arnaud 2005, 23 (4):  353-357.  Abstract ( 2292 )   [Full Text(HTML)] () PDF (208KB) ( 703 )   As one of the main phytoalexins and phytoestrogens, glyceollin is an important prenylflavonoid in Glycine max ［L.］ Merri. (soybean). Many kinds of elicitors can be used to induce its accumulation. Its biosynthesis pathway is commonly used to study the characteristics of prenyltransferase, which catalyzes the prenylated reaction happening in a very few plant families in nature. Glycinol, the direct precursor of glyceollin, is necessary to study the prenylated reaction in soybean. In comparing with the other elicitors to elicit the glycinol accumulation in soybean cotyledons, AgNO3 is the most effective elicitor. Exposure of 6-8 days old cotyledons to 0.01 mol/L AgNO3 and incubation for 24 h result in the accumulation of 256 μg (glycinol)/g (fresh weight). The glycinol was extracted by methanol. Then the isolation and purification were conducted by preparative high performance liquid chromatography. Instead of 100% acetonitrile-0.1% formic acid as the elution system, the extract was eluted by 100% methanol-0.1% formic acid. Glycinol eluted earlier than daidzin under this system and decreased the disturbance from the large amount of daidzin. Identification was performed by comparing the mass spectrum (liquid chromatography/quadrupole-time of flight) and ultraviolet spectrum with those of the standard. At last, 100 mg purified glycinol was obtained from 390 g of fresh material.

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Determination of Sildenafil and Vardenafil in Human Plasma by High Performance Liquid Chromatography Coupled with Liquid-Liquid-Liquid Microextraction ZHANG Zhaohui, KANG Shaoying, XU Minjie, MA Ming, CHEN Bo, YAO Shouzhuo 2005, 23 (4):  358-361.  Abstract ( 2265 )   [Full Text(HTML)] () PDF (156KB) ( 1177 )   High performance liquid chromatography coupled with liquid-liquid-liquid microextraction was developed for the simultaneous determination of sildenafil and vardenafil in human plasma. The effects of extraction solvent, the volume of organic solvent, dropsize of acceptor phase, stirring rate and extraction time on the enrichment factors of analytes were investigated. The optimized experimental conditions, 300 μL toluene as the organic phase, 2 μL 0.2 mol/L HCl as the acceptor phase, 600 r/min of the stirring rate, and 40 min of the extraction time, were gotten. Under these conditions, high enrichment factors were obtained. The linear range of studied analytes was from 5 μg/L to 1.0 mg/L. The relative standard deviation was lower than 5%. The limits of detection were 1 μg/L for sildenafil and 0.5 μg/L for vardenafil at signal-to-noise ratio of 3. The method with little solvent consumption may provide high analyte pre-concentration and excellent sample clean-up, and it is a sensitive and suitable method for simultaneous determination of the above two substances in human plasma.

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Analysis of Nonylphenol, Octylphenol and Bisphenol A in Animal Tissues by Liquid Chromatography-Tandem Mass Spectrometry with Accelerated Solvent Extraction SHAO Bing, HAN Hao, LI Dongmei, ZHAO Rong, MENG Juan, MA Yalu 2005, 23 (4):  362-365.  Abstract ( 2457 )   [Full Text(HTML)] () PDF (161KB) ( 1239 )   A comprehensive analytical method based on liquid chromatography-electrospray ionization tandem mass spectrometry with negative ionization mode has been developed for measuring alkylphenols (AP) and bisphenol A (BPA) in animal tissues. Samples of animal tissues were extracted by accelerated solvent extraction with dichloromethane. Sample concentration and purification were performed using an OASIS NH2 solid extraction cartridge. The effects of mobile phase and additives on ionization were assessed. The recoveries for the compounds ranged from 88% to 101% and the relative standard deviations were below 15%. The detection limits of the method under multiple-reaction monitoring mode were 0.3, 0.05 and 0.1 μg/kg for BPA, nonylphenol (NP) and octylphenol (OP), respectively. The contents of NP ranging from 0.49 to 55.98 μg/kg were found in 27 real samples of animal tissues from Beijing market. The results indicate that the endocrine disrupting nonylphenol is ubiquitous in food of animal origin. Nonylphenol was found in all fish samples with concentration levels ranging from 9.13 to 55.98 μg/kg.

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Determination of Peroxides in Environmental Samples by High Performance Liquid Chromatography XU Jinrong, CHEN Zhongming 2005, 23 (4):  366-369.  Abstract ( 2217 )   [Full Text(HTML)] () PDF (144KB) ( 815 )   A high performance liquid chromatographic (HPLC) method with fluorescence detection was developed for the determination of hydrogen peroxide and organic peroxides in environmental samples, and the method has been applied to peroxides detection in urban air and rain samples. The analytical sensitivity was improved. Post-column derivatization involved the oxidation of peroxides to a fluorescent dimer using p-hydroxyphenylacetic acid, a reaction catalyzed by hemin. The optimal excitation wavelength was 315 nm, while the emission wavelength was 400 nm. The temperature of the reaction coil was controlled at about 30 ℃. Based on the ratio of signal to noise of 3, the detection limits were 4.0×10-9 mol/L for hydroperoxide (H2O2), 4.1×10-8 mol/L for methylhydroperoxide (MHP) and 6.7×10-8　mol/L for ethylhydroperoxide (EHP) for aqueous samples. While the corresponding detection limits were 2.4 ng/m3 for H2O2, 35.2 ng/m3 for MHP, and 74.4 ng/m3 for EHP for air samples. Air samples were collected by Horibe cold trap at the temperature of about -90 ℃. The results show that H2O2, hydroxymethyl hydroperoxide (HMHP), MHP, and EHP were the major peroxides in air, and that peroxyacetic acid (PAA) was occasionally detected. In rain samples, the two major peroxides were H2O2 and HMHP.

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Study on Trace Component in Sex Pheromones of Dendrolimus spp. KONG Xiangbo, ZHANG Zhen, WANG Hongbin, ZHAO Chenghua 2005, 23 (4):  370-373.  Abstract ( 2132 )   [Full Text(HTML)] () PDF (141KB) ( 627 )   Two compounds were isolated, as sex pheromone components, from the abdominal tips of the female pine caterpillar moth, Dendrolimus kikuchii. The major component was identified as (Z,E)-5,7-dodecadien-1-yl acetate by gas chromatography and mass spectrometry. There are some difficulties to elucidate the structure of the minor component due to its trace and coelution with other components. The derivatives of alkaline methanolysis and reacetylation of pheromone gland extracts of D. kikuchii were analyzed by high-resolution gas chromatography, which was performed to verify the functional group and stereo isomers of the trace component in the pheromone gland extracts. The trace component was characterized as (Z,E)-5,7-dodecadienol via microchemical reaction. The advantages of the conversion of acetates to corresponding alcohols or of alcohols to the corresponding acetates in identifying the trace component of pheromone gland extracts of D. kikuchii were discussed. The importance of identifying the trace component in pheromone chemical communication system of insects is emphasized.

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Quantitative Analysis of Cantide in Plasma by Capillary Gel Electrophoresis ZHANG Wei, YANG Binghu, LIANG Qiande, LU Dandan, LIN Ruxian, WANG Shengqi 2005, 23 (4):  374-377.  Abstract ( 2674 )   [Full Text(HTML)] () PDF (145KB) ( 690 )   Cantide is a 20-merantisense phosphorothioate oligonucleotide that inhibits telomerase catalytic subunit hTERT, pharmacologic results showed that it had promising antitumor activity. In order to study the pharmacokinetic properties of Cantide, a capillary gel electrophoretic (CGE) method with internal standard was used for the determination of Cantide in rat plasma. Cantide and the internal standard had approximately equal percentage of base composition. Extraction of the phosphorothioate oligonucleotides from plasma was accomplished using two solid-phase extraction columns, a strong anion-exchange column to remove plasma proteins and lipids, followed by a reversed-phase column to remove plasma salts. A second desalting step, achieved by dialysis utilizing a membrane, was required to remove residual ionic material from the extracted sample. The size of the capillary column was 31 cm×100 μm i.d. with an effective length of 20 cm. The running buffer was a mixture of Tris-boric acid-urea (pH 8.5). The calibration curve was linear in the range of 12.5-400 mg/L, with correlation coefficient (r) of 0.9998. Intra-day and inter-day relative standard deviations (RSDs) for the extracted samples were 0.398%-2.46% and 2.75%-6.07%, respectively. The range of recoveries was 99.53%-102.1%. The results demonstrate the high accuracy,stability and reproducibility of the procedure.

Reviews

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Immobilized Artificial Membrane Chromatography and Its Application in Profiling the Drug Membrane Transport SUN Jin, ZHANG Tianhong, HE Zhonggui 2005, 23 (4):  378-383.  Abstract ( 1946 )   [Full Text(HTML)] () PDF (190KB) ( 882 )   Immobilized artificial membrane chromatography (IAMC) is a system of covalently bonding monolayer of phospholipid analogs onto the solid surface of silica particles, thus establishing the emulating process of drug-cellular membrane interactions in terms of chromatographic method, and is applied to profile the drug membrane permeability and biological activity. IAMC phases prepared from phosphocholine analogues closely mimic the surface of the biological cell membrane, and the capacity factor of drugs can be used to predict the interaction between drug molecules and cell membranes. IAMC, compared with n-octanol/water, liposome/water and ODS chromatography, can simulate other forces besides hydrophobic interaction. IAMC is getting more and more profound research because of its convenience and high efficiency. The primary screening by means of IAMC in the early stage of drug development would effectively lower failure in the preclinical and clinical development, since efficacy and safety are related in the larger part to membrane permeability. The interaction mechanism of drug-IAM and its profiling in membrane transport are reviewed.

研究简报

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Studies on Chromatographic Properties of 2,4,6-Trinitrophenol-Modified Zirconia-Magnesia YU Qiongwei, SHI Zhiguo, FENG Yuqi, DA Shilu, LI Ting 2005, 23 (4):  384-388.  Abstract ( 1765 )   [Full Text(HTML)] () PDF (186KB) ( 661 )   A stationary phase for the separation of C60 and C70 was prepared by modifying zirconia-magnesia composites with 2,4,6-trinitrophenol. The modified composite was characterized by using elemental analysis, diffused reflectance Fourier transform infrared spectroscopy and specific surface area. The effects of the toluene content in toluene-cyclohexane mobile phase and the column temperature on the separation of C60 and C70 were examined. Meanwhile, the separation of fullerenes including 3% high fullerenes was investigated at the temperature of 348 K using pure toluene as the mobile phase. The results showed that the stationary phase of 2,4,6-trinitrophenol-modified zirconia-magnesia composite exhibits advantage in the separation of C60 and C70, and strong temperature dependence. The retention times of C60 and C70 and their separation factor on the stationary phase increase with the increase of the column temperature. The stationary phase is a potential packing material for separation of fullerenes in preparative scale.

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Analysis of Ginsenosides in Ginseng by Liquid Chromatography-Atmospheric Pressure Chemical Ionization Mass Spectrometry MA Xiaoqiong, XU Qing, LIANG Xinmiao 2005, 23 (4):  389-393.  Abstract ( 2082 )   [Full Text(HTML)] () PDF (194KB) ( 659 )   Analysis of ginsenosides using high performance liquid chromatography-tandem atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI/MS) has been carried out. HPLC analysis was performed on a reversed-phase C18 column using mobile phase of acetonitrile and water mixture under gradient elution. Effects of evaporation temperature of APCI-MS on identification of ginsenosides were investigated. APCI/MS-MS spectra of ［M-H］- were further resolved to identify the structures of ginsenosides. Detection limits of ginsenosides Rb1 and Rg1 were determined under selected reaction monitoring (SRM) mode. Ginsenosides in Panax ginseng (white ginseng) were assayed. Results show that although APCI is a high temperature evaporative process and ginsenosides are thermolabile compounds, abundant ［M-H］- ions could be detected by using APCI-MS. The intensity of ［M-H］- increased with the increase of evaporation temperature, which may due to more complete evaporation of elute solution at higher temperatures or due to the ionization mechanism of APCI. The detection limits of Rb1 and Rg1 were 1.2×10-13 g and 3.0×10-14 g, respectively. Twenty nine ginsenosides including malonyl-ginsenosides in Panax ginseng were identified. The method developed is sensitive, reproducible and accurate. Most ginsenosides in the extracts of ginseng could be effectively identified and analyzed for their structures.

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Determination of Relative Molecular Mass and Composition for Polygonatum sibiricum Polysaccharide by ZHANG Xiaohong, Gereltu Borjihan, Zhaorigetu, Narisu 2005, 23 (4):  394-396.  Abstract ( 2738 )   [Full Text(HTML)] () PDF (113KB) ( 1032 )   Polygonatum sibiricum Redoute (PSR) is a traditional Chinese medicine and Mongolia herbal medicine growing in Inner Mongolia. Polygonatum Sibiricum Polysaccharide (PSP) was isolated and purified with boiling water extraction, alcohol precipitation from the wild species roots of PSR. Proteins was removed from the crude PSP by methods of trypsin hydrolysate and Sevag. Purity, relative molecular mass and relative molecular mass distribution of PSP were determined using high performance liquid chromatography (HPLC). The buffer solution of NaH2PO4-Na2HPO4 (0.02 mol/L) was used as mobile phase, and the PSP was separated on a Shodex GPC column as a single symmetrical peak corresponding to a number mean molecular mass (Mn) of 7073 and relative molecular mass (Mr) of 7247, and polydispersity is 1.025. The sugar components of the PSP was analysed by HPLC and 13C NMR. Using water as mobile phase, the components of all acid hydrolysis of the PSP were separated on a Shodex SP0810 column. Glucose, galactose, mannose and fructose were used as the standard samples. The result showed that PSP is composed of fructose only.

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Qualification and Quantification of 10 Sulfonamides in Animal Feedstuff by High Performance Liquid Chromatography-Electrospray Tandem Mass Spectrometry QIN Yan, ZHANG Meijin, LIN Haidan 2005, 23 (4):  397-400.  Abstract ( 2090 )   [Full Text(HTML)] () PDF (164KB) ( 858 )   The presence of sulfonamide (SA) residues in foods is largely due to the raising of animals with sulfonamide antibiotics added or polluted feedstuff. Because of interference from the matrices, the commonly used immunoassay or chromatographic method is not suitable for the analysis of multi-SAs in feedstuff. A high performance liquid chromatographic-electrospray tandem mass spectrometric (HPLC/ESI-MS-MS) method has been established for the simultaneous determination of multi-SAs including sulfadiazine (SD), sulfapyridine (SPD), sulfamerazine (SM1), sulfameter (SM), sulfamethazine (SM2), sulfamethoxypyridazine (SMP), sulfamethoxazole (SMZ), sulfamonomethoxine (SMM), sulfadimethoxine (SDM) and sulfaquinoxaline (SQX). After solvent extraction, solid phase extraction, dilution and reversed-phase HPLC separation, SAs were detected by ESI-MS-MS under multi-reaction monitoring mode. The qualification analysis was done by using retention time and distribution of diagnostic ion pairs, and the quantification was based on the peak intensity of common fragment ion m/z 156. The limits of quantification for 10 SAs were 0.5-2.0 μg/kg (S/N=10). The correlation coefficient of linear calibration curve was over 0.9995 within the SAs concentration range 2.0-200 μg/L except for SDM and SQX. At the spiked level of 1.0 mg/kg, the average recoveries for the 10 SAs were between 70% and 92%, the relative standard deviations were under 10% for intra-day and under 15% for inter-day. Routine tests showed the method was fast, sensitive, specific, and practical for the SAs determination in feedstuff.

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Simultaneous Determination of Four Fluoroquinolone Residues in Fish by Ion-Pair High Performance Liquid Chromatography GUO Genhe, PAN Wei, SU Desen, CHEN Hanzhen 2005, 23 (4):  401-403.  Abstract ( 1975 )   [Full Text(HTML)] () PDF (116KB) ( 882 )   An ion-pair high performance liquid chromatographic method with a fluorescence detector was established to determine four fluoroquinolone residues in fish. The chromatographic conditions were as follows: Waters μBondapakTM C18 column (3.9 mm i.d.×300 mm, 10 μm) was used at 40 ℃ with 11 mmol/L tetrabutylammonium bromide solution (pH 3.0)-acetonitrile (94∶6, v/v) as the mobile phase with a flow rate of 1.0 mL/min, at the excitation wavelength of 280 nm and emission wavelength of 460 nm. The detection limit for fish was 1 μg/kg. The linear range was from 6-100 μg/kg, and correlation coefficients were more than 0.9995. At the levels of 10, 50 and 100 μg/kg, the recoveries were 76%-100% with relative standard deviations of less than 7%. The method developed can meet the requirement for residue analysis.

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Simultaneous Determination of Seventeen Sulfonamide Residues in Chickens by Liquid Chromatography- DONG Dan, SHAO Bing, WU Yongning , WU Guohua, XUE Ying,XU Shukun, TU Xiaoming, ZHANG Yanfeng 2005, 23 (4):  404-407.  Abstract ( 2111 )   [Full Text(HTML)] () PDF (161KB) ( 1203 )   A liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of seventeen commonly used sulfonamide (SA) residues in chickens has been developed. Stable isotopic compound 13C6-sulfamethazine was used as internal standard. Multi-reaction monitoring mode was employed for the quantitative determination. The separation was performed on a Capcell Pak C8 DD column (150 mm×2.0 mm i.d., 5 μm) with a gradient system of water (containing 0.2% formic acid)-methanol (containing 0.2% formic acid) as mobile phase at a flow rate of 0.2 mL/min. Samples were prepared by homogenizing the chicken, extracting with acetonitrile, defatting with n-hexane and cleaning-up with Sep-Pak Silica solid-phase extraction. The detection limits of 0.02-1 μg/kg proved to be much better than the previously reported ones. Average recoveries of seventeen SAs (spiked at the levels of 1, 5, 10 μg/kg) ranged from 52.3% to 124.9%, with relative standard deviations between 1.0% and 17.6%. Intra-day and inter-day variations of the method were all with in the acceptable ranges. The results demonstrated that the method is simple, accurate and suitable for the identification and quantification of these sulfonamide residues in chickens.

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Determination of Amino Acids in Isatis indigotica Fort by Reversed-Phase High Performance Liquid WAN Shaohui, YANG Hao, GENG Xiumei 2005, 23 (4):  408-410.  Abstract ( 2179 )   [Full Text(HTML)] () PDF (115KB) ( 869 )   A reversed-phase high performance liquid chromatographic method with pre-column derivatization for the determination of amino acids, which were known as the characteristic constituents of Isatis indigotica Fort was established. The amino acids in alkalescence were derivatized with 2,4-dinitro-fluorobenzene (DNFB). A reproducible method for simultaneous qualitative analysis of glutamic acid (Glu), argirine (Arg) and proline (Pro) and quantitative analysis of Arg and Pro in Isatis indigotica Fort has been established. NaAc buffer (pH 6.4)-acetonitrile (85∶15, v/v) as mobile phase and a Sinochrom ODS-BP column were used. The detector was operated at 360 nm. The linear regressions of the standard curves were determined for Arg and for Pro. The method was carried out over the range of 0.627-5.016 μg for Arg and 0.874-7.000 μg for Pro. The recoveries were 98.5% and 98.4% with the relative standard deviations of 2.5% and 2.3% for Arg and Pro respectively. The results indicate that among the three amino acids in Isatis indigotica Fort, Arg content was the highest, Pro the second and Glu the lowest. The method has good accuracy and repeatability and it can be used for the quality control of Isatis indigotica Fort.

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Separation and Purification of the Main Glucosinolate from Rapeseeds ZHOU Jinlan, HU Jianhua, QIU Aiyong 2005, 23 (4):  411-414.  Abstract ( 6064 )   [Full Text(HTML)] () PDF (138KB) ( 845 )   A procedure for the preparative isolation of 1-S-［(1Z)-3-hydroxy-1-［(sulfooxy) imino］-4-pentenyl］-1-thio-β-D-glucopyanose, potassium salt (progoitrin) from Brassica oleracea is reported. The major steps in this procedure were: (1) extraction of glucosinolates with methanol from Brassica oleracea; (2) separation and purification of glucosinolates by chromatographic column on alumina support; and (3) a follow-up reversed-phase separation by octadecyl (C18) silica support yielding progoitrin as the main content of glucosinolate. The structure of progoitrin was identified on its physicochemical properties by ultraviolet absorption spectrometry, infrared absorption, 1H nuclear magnetic resonance spectroscopy, mass spectrometry and elemental analysis. Spectroscopic data of the sample isolated were in agreement with those reported in the literature.The purity of progoitrin obtained was determined to be 99% by high performance liquid chromatography. The simplicity of the separation and purification procedure for glucosinolates and the high purity of progoitrin isolated would make the method an important reference for future research on glucosinolates and a favorable technique for future development.

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Resolution of Carotenoid Isomers in Lycium barbarum L. by Heuristic Evolving Latent Projection LU Hongmei 2005, 23 (4):  415-417.  Abstract ( 2121 )   [Full Text(HTML)] () PDF (140KB) ( 691 )   Lycium barbarum L., a kind of traditional Chinese herb, is found to have bioactivities such as anticancer, antioxidant, hypoglycemic and immunological activities. In both in vitro and in vivo studies, the carotenoids were found to be a class of the effective compounds. The carotenoids in Lycium barbarum L. were separated by high performance liquid chromatography with diode array detection (HPLC-DAD). Seven peaks were obtained by HPLC on a C18 column with acetonitrile-methylene chloride (60∶40, v/v) as mobile phase at a flow-rate of 1.0 mL/min. Most of the peaks that had been validated as single peaks in the 2-dimensional chromatography were found to be overlapping peaks. The overlapping chromatographic peaks were resolved by chemometric methodHeuristic Evolving Latent Projection (HELP) based on 3-dimensional data. As an example, the chromatogram and UV spectra of 4 isomers were obtained by resolving an overlapping peak. These results showed that the combination of chemometric methods and modern analytical instruments provides an effective method for the analysis of complex systems such as isomers.

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Characterization and Identification of Ralstonia solanacearum by Ion-Exchange Chromatography ZHANG Yang, WEN Teng, LIN Juan, XIE Zhi, LIU Shutao, RAO Pingfan 2005, 23 (4):  418-421.  Abstract ( 1950 )   [Full Text(HTML)] () PDF (161KB) ( 776 )   Ralstonia solanacearum, a widely distributed and economically important plant pathogen, was characterized by ion-exchange chromatography (IEC). Ralstonia solanacearum was chromatographed on a TOYOPEARL SuperQ-650 C column (200 mm×4.6 mm i.d.) with gradient elution by A (0.02 mol/L piperazidine-chlorhydric acid buffer (pH 8.0)) and B (A+1 mol/L NaCl). The pure culture of R. solanacearum was separated into three fractions on a SuperQ-650 C column. They were found all belong to R. solanacearum after the fractions were identified by other biochemical methods. Because of their ability to oxidize 3 disaccharides (lactose, maltose and cellobiose) and 3 hexose alcohols (mannitol, sorbitol and dulcitol), they are classified as biovar Ⅲ of R. solanacearum. Once the mobility was scaled using microscope and the pathogenetic ability was measured with 2,3,4-triphenyltetrazolium chlorid (TTC) medium, the two fractions were in different states. The results are very important to elucidate the multi-states of R.solanacearum and the mechanism of R.solanacearum’s pathogenetic mutation.

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Classification of Terpenes and Terpene Oxides in Volatile Oil of Fruit of Acanthopanax senticosus (Rupr. Et Maxim) Harms with Gas Chromatographic Retention Parameters XUE Xingya, YU Wanying, CHEN Jiping, HUANG Weidong, LIANG Xinmiao 2005, 23 (4):  422-425.  Abstract ( 2829 )   [Full Text(HTML)] () PDF (175KB) ( 705 )   Gas chromatographic (GC) retention parameters (A and B values) for 24 volatile compounds in volatile oil of Acanthopanax senticosus (Rupr. Et Maxim) Harms were obtained from the retention times under five temperature-programming conditions with self-developed GC_AB software based on Levenberg-Marquardt method. The correlation analysis between A and B parameters of terpene and its oxides was carried out. Good linear relationships between A and B parameters were built for seven monoterpenes (C10H16), nine sesquiterpenes (C15H24), three monoterpene oxides (C10HnO) and three sesquiterpene oxides (C15HnOx) at the same carbon number, respectively. But poor A-B linearity was built for the group formed from monoterpenes and monoterpene oxides or that formed from sesquiterpenes and sesquiterpene oxides at the same carbon number. At the same time the A-B relationships for monoterpenes, sesquiterpenes and their oxides are not collinear. Therefore, this discipline is applied in the assistant identification for terpenes with different carbon numbers and in the classification between terpenes and their oxides. It shows that GC retention parameters calculated from retention times under several temperature-programming conditions are useful for the classification of monoterpenes, sesquiterpenes and their oxides in the analysis of volatile oils from traditional Chinese herbs.

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Quantitative Evaluation of the Variation of Aroma Harmony in Processed Fruit and Vegetable Juices with Gas Chromatographic Data LIU Ling, CUI Mingxue, XUE Yi 2005, 23 (4):  426-430.  Abstract ( 1963 )   [Full Text(HTML)] () PDF (143KB) ( 620 )   To develop a quantitative evaluation model for the variation of aroma harmony in processed fruit and vegetable juices， gas chromatographic data from juice samples were summed up by mathematic modeling. Based on the original fruit and vegetable juices, the total change in volatile compounds expressed in term of percentage between the treated samples by various processes and the original juice, that is, the deviation of samples, are calculated. They were then used to describe the total change of aroma compounds in the fruit and vegetable juices before and after the processing. To compare the influences of different processes on aroma harmony in fruit and vegetable juices, the samples were analyzed by gas chromatography under the same conditions and the data were obtained by comparing the deviations of the samples. The lemon juices concentrated either by freeze-concentration or by vacuum evaporation were compared against the original lemon juices. The results showed that the freeze-concentration well retained not only the absolute contents of aroma compounds but also the aroma harmony of natural lemons.

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Resolution of Clenbuterol Hydrochloride Enantiomers by Thin-Layer Chromatography on Silica Gel YU Jingang, HUANG Kelong, JIAO Feipeng, PENG Xiahui 2005, 23 (4):  431-433.  Abstract ( 2403 )   [Full Text(HTML)] () PDF (115KB) ( 740 )   The resolution of clenbuterol hydrochloride enantiomers was achieved by thin-layer chromatography on silica gel GF254 plates impregnated with β-cyclodextrin. The effect of stereoselective auxiliary (acetonitrile and alcohol) was investigated. Resolution of clenbuterol hydrochloride enantiomers could be attained by using alcohols of butanol, 2-butanol or tert-butanol together with acetonitrile as developing solvent. The optimal conditions of resolution were determined as follows: a plate prepared with 15.00 g silica gel GF254 impregnated with 1.00 g β-cyclodextrin, acetonitrile-2-butanol (20∶80, v/v) as developing solvent and developed at room temperature. Under these conditions, Rf of the two isomers of clenbuterol hydrochloride enantiomers were 0.34 and 0.72 respectively. The resolution was 4.09 with baseline separation and the spots in chromatogram were almost of the same size.