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    Chinese Journal of Chromatography
    2009, Vol. 27, No. 1
    Online: 30 January 2009

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    Reviews
    Advances of solid-phase microextraction and current status of application in food analysis
    HU Guodong
    2009, 27 (1):  1-8. 
    Abstract ( 2689 )   [Full Text(HTML)] () PDF (224KB) ( 1125 )  
    Solid-phase microextraction (SPME) has been widely used as a sample preparation technique in current chromatography. SPME integrates extraction, concentration, desorption and injection in one step, which is highly sensitive and easy to operate. This review briefly introduces the evolution of the coating, equipment and corresponding techniques of SPME in recent years. It also summarizes SPME applications in food analysis and discusses some of the common issues found in quantitative analysis.
    Applications of capillary electrophoresis and capillary electro-chromatography in the detection of pesticide residues
    LIN Zhenyu, HUANG Lu, CHEN Guonan
    2009, 27 (1):  9-18. 
    Abstract ( 2497 )   [Full Text(HTML)] () PDF (273KB) ( 1046 )  
    Capillary electrophoresis (CE) and capillary electrochromatography (CEC) have some outstanding advantages, such as less sample consumption and high separation efficiency. Coupled with different detection modes, such as ultraviolet detection, laser-induced fluorescence, amperometry, conductometry, mass spectrometry, and various sample preconcentration methods, CE and CEC have been accepted by more and more analysts in the detections of pesticide residues. This review focuses on the comparison of the merits and demerits of various detection modes in pesticide residue detections. The preconcentration methods of pesticide residues have been discussed briefly also. Special attention has been paid on the separation and detection of enantiomeric pesticide compounds. Expectation on the applications of CE and CEC is also outlined.
    Communications
    Cleavage of amide bond during glycopeptide enrichment using wheat germ agglutinin affinity chromatography
    LU Zhuang, WANG Jinglan, JIA Wei, YANG Bing, CAI Yun, DENG Yulin, ZHANG Yukui, QIAN Xiaohong,
    2009, 27 (1):  19-23. 
    Abstract ( 2416 )   [Full Text(HTML)] () PDF (4372KB) ( 652 )  
    As one of the most important post-translational modifications (PTMs), glycosylation has a significant effect on the structure and functions of proteins. One of the important tools for glycoprotein research is lectins, which are known to have the ability to bind specific oligosaccharide moieties. Many different pure lectins are commercially available in an immobilized form suitable for glycoprotein purification, in which, wheat germ agglutinin (WGA) is the most popular one for its broad binding ability for different glycans. Lectins are usually used for the enrichment of glycoproteins or glycopeptides. In our research, the amide bind of peptides, including glycopeptides, can be cleavaged when the peptide mixture passes through the lectin column, which will lead a failure in sequent identification. Four standard proteins were used to verify this phenomenon and the peptide degradation was confirmed. The cleavage can occur at many positions, but more inclined to the C-terminal of the peptides with the amino acid residual of phenylalanine (Phe), leucine (Leu) and tyrosine (Tyr). From this result, we first revealed the problem existed in the affinity separation strategy of glycopeptides using WGA in proteomics research very popularly and suggested that using partial or no enzyme digestion database searching parameter would be more suitable for glycopeptides identification after WGA enrichment.
    Articles
    Separation and identification of oligosaccharides labeled with 3-amino-9-ethylcarbazole using high performance liquid chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
    MOU Qing, ZHANG Ying, HUANG Linjuan, WANG Zhongfu
    2009, 27 (1):  24-28. 
    Abstract ( 2544 )   [Full Text(HTML)] () PDF (6571KB) ( 642 )  
    A pre-column derivatization method for the determination of oligosaccharides based on a labeling reagent 3-amino-9-ethylcarbazole (AEC) was proposed. The enamines were generated by the reaction of the reducing ends of oligosaccharides and the primary amines of AEC, and then reduced to secondary amines by NaBH3CN, making oligosaccharides labeled by AEC. The derivatives were separated by reversed-phase high performance liquid chromatography (RP-HPLC), and then directly analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The HPLC separation was carried out on a Waters Symmetry C18 column (3.9 mm×150 mm, 5 μm) with a gradient elution (acetonitrile and ammonium acetate as mobile phases at a flow rate of 1 mL/min) and ultraviolet detection at 254 nm. Under the optimized derivatization and HPLC conditions, the derivatized oligosaccharides were separated, and the derivatization with AEC increased the sensitivity of MS detection. The developed method for the analysis of oligosaccharides is satisfactory.
    Separation and identification of the impurities in monosialotetrahexosylgangliosides by high performance liquid chromatography-tandem mass spectrometry
    WANG Hua, XU Yuan, LIANG Feng, QI Yanxia, GUAN Yafeng
    2009, 27 (1):  29-33. 
    Abstract ( 2604 )   [Full Text(HTML)] () PDF (6904KB) ( 1102 )  
    Comparative analysis of impurities in batches of monosialotetrahexosylganglioside (GM1) powder, injections, and the intermediates for the synthesis of GM1 was performed by using high performance liquid chromatography in order to find out the possible impurities that lead to the clinical side effects. We found that there were two additional peaks in a batch of GM1 powder with retention times that were the same as that presented in the intermediates. The semi-preparative separation and collection of the two impurities in the GM1 powder and intermediates were performed, and then freeze-dried and enriched about 35 times for structure analysis. They were confirmed that the peak 1 and peak 1′ were the same compound, and so did the peak 2 and peak 2′ by electrospray ionization-quadrupole-time of flight mass spectrometric (ESI-Q-TOF MS) analysis. The structures of the compounds were deduced based on the tandem mass spectra of the main ions, proposed to be fucose-GM1. The two impurities were different on the hydrocarbon chain of the ceramide. The peak 1 has 16 groups of CH2, while the peak 2 has 18. The analysis results were consistent with the clinical results for both GM1 powder and injections. It was confirmed that the two impurities were the main cause of the side effects.
    Simultaneous determination of 19 quinolone residues in honey using high performance liquid chromatography-tandem mass spectrometry
    DING Tao, SHEN Dongxu, XU Jinzhong, WU Bin, CHEN Huilan, SHEN Chongyu, SHEN Weijian, ZHAO Zengyun, LIAN Hongzhen
    2009, 27 (1):  34-38. 
    Abstract ( 2532 )   [Full Text(HTML)] () PDF (7351KB) ( 598 )  
    A method for the simultaneous analysis of 19 quinolone residues, enrofloxacin, ciprofloxacin, norfloxacin, ofloxacin, difloxacin, oxolinic acid, flumequine, sarafloxacin, sparfloxacin, danofloxacin, fleroxacin, marbofloxacin, enofloxacin, orbifloxacin, pipemidic acid, pefloxacin, lomefloxacin, cinofloxacin, and nalidixic acid in honey was developed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). In comparison of the three different extraction methods, i.e. acid solution coupled with cation-exchange solid-phase extraction cartridge (PCX), neutral buffer solution coupled with a reversed-phase extraction cartridge (HLB) and alkali solution coupled with a strong anion-exchange solid-phase extraction cartridge (PAX), the third method was finally used. The cartridge was then applied to accumulate and purify the target analytes from the sample matrices in one step. The HPLC separation was performed on a C18 column with a linear gradient elution program of methanol and 0.1% formic acid solution as the mobile phase. Selective reaction monitoring (SRM) was used for the selective detection of 19 quinolones. The linearity of all the 19 quinolones in the range from 1 μg/L to 100 μg/L had correlation coefficient greater than 0.991. In the detection of spiked samples, the detection limit of the method was 1.0 μg/kg for all the 19 quinolones, and the recoveries were 71%-118% with the relative standard deviations of 4.2%-6.7%. Internal standard calibration was used for the quantitative analysis.
    Determination of ciprofloxacin residue in fish/shellfish tissues using liquid chromatography-tandem mass spectrometry with isotope internal standard dilution technique
    CHEN Xiaohong, WANG Yufei, YAO Xunping, JIN Micong
    2009, 27 (1):  39-43. 
    Abstract ( 2448 )   [Full Text(HTML)] () PDF (505KB) ( 644 )  
    Using isotope internal standard dilution technique, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed for the identification and quantitative determination of ciprofloxacin residue in the tissues of various fishes/shellfishes. The homogenized tissue sample added with ciprofloxacin-D8 and phosphate buffer solution (pH 7.0) was extracted with acetonitrile under ultrasonication, and degreased with hexane. After solid-phase extraction (SPE) was performed on an Oasis MAX cartridge, the sample was separated on a Cloversil-C18 column (150 mm×4.6 mm, 5 μm) by using the mobile phase consisting of CH3CN-0.05%CF3COOH (25∶75, v/v). The detection was carried out by LC-MS/MS using an electrospray ionization interface in multiple reaction monitoring (MRM) mode. The quantification using isotope-labelled internal standard was based on the peak area ratio of ciprofloxacin and deuterated internal standard in the MRM mode. The calibration curve was linear within the range of 0.1-50.0 μg/kg and the limit of quantification was 0.1 μg/kg (S/N≥10). The recovery was between 92.5% and 98.1%, and the relative standard deviation was less than 4.3%. The application of this method was further demonstrated by analyzing ten various real samples from local markets. The results show that this method is sensitive, accurate and suitable for the confirmative determination of ciprofloxacin residues.
    Simultaneous determination of 8 illegal synthetic drugs in antihypertensive dietary supplements by high performance liquid chromatography-mass spectrometry
    LU Yaling, CHEN Jitao, CHEN Bo, YAO Shouzhuo
    2009, 27 (1):  44-49. 
    Abstract ( 2465 )   [Full Text(HTML)] () PDF (802KB) ( 774 )  
    A method of high performance liquid chromatography-mass spectrometry (HPLC-MS) for the simultaneous determination of 8 illegal synthetic drugs in antihypertensive dietary supplements was developed. The chromatography was performed using a Spherigel C18 column, with the mobile phase of 0.005 mol/L ammonium formate buffer (pH 3.0)-acetonitrile-methanol and cialis as internal standard. In ESI+ mode, the lowest concentration limit of detection (LOD) was 2.5 μg/L and the lowest concentration limit of quantification (LOQ) was 8.3 μg/L, while in ESI- mode, the lowest concentration limit of detection (LOD) was 50 μg/L. The average recoveries were between 63.3%-107.4%. The clonidine, dihydrochlorothiazide, triamterene, metoprolol, phentolamine, chlorthalidone, furosemide and valsartan in the samples were separated well under the optimized conditions. The method was well validated by systematical searching for satisfactory conditions using the experimental designs including precision, repeatability and spiked recovery.
    Determination of common antibiotics and metronidazole in cosmetics by ultra performance liquid chromatography-tandem mass spectrometry
    LIU Hualiang, LI Fang, YANG Run, WANG Lianhong, MA Yongjian
    2009, 27 (1):  50-53. 
    Abstract ( 2616 )   [Full Text(HTML)] () PDF (355KB) ( 1292 )  
    A method for the analysis of common antibiotics and metronidazole in cosmetics was developed by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). One gram of each cosmetic sample was extracted by methanol-water containing 0.1 mol/L formic acid (1∶1, v/v). The extracted sample was filtered before being analyzed with UPLC/MS/MS. The effects of formic acid concentration in the mobile phase on the sensitivity and retention time were studied, and the results showed that 1% was the optimum concentration. Seven analytes, minocycline, oxytetracycline, tetracycline, chlortetracycline, doxycycline, chloramphenicol, metronidazole, can be separated and detected in 5 min, which is much faster than that by the conventional liquid chromatography. The detection limits were 3-20 ng/g, and the recoveries were 87%-101%. The calibration curves showed good linearity in the range of 2-1000 μg/L with correlation coefficients larger than 0.995. The method was also applied to determine common antibiotics and metronidazole in 11 real samples from themarket. Chloramphenicol was detected in 2 samples and the concentrations were 0.37% and 0.19%; metronidazole was detected in 1 sample and the concentration was 1.02%; others were not detected.
    Simultaneous determination of tetracycline and quinolone antibiotics in environmental water samples using solid phase extraction-ultra pressure liquid chromatography coupled with tandem mass spectrometry
    SUN Guangda, SU Zhongyi, CHEN Meng, YUAN Dongxing
    2009, 27 (1):  54-58. 
    Abstract ( 2663 )   [Full Text(HTML)] () PDF (2594KB) ( 943 )  
    Using HLB cartridge for extraction and cleanup, a method for simultaneous determination of 4 tetracycline and 6 quinolone antibiotics in environmental water samples was developed by ultra pressure liquid chromatography coupled with tandem mass spectrometry. Using river water and sea water as matrices and carbadox as surrogate, the recoveries and relative standard deviations (RSD, n=4) were 94.0%-117.0% and 2.0%-9.7% for 4 tetracyclines at 20.0 ng/L and 100.0 ng/L spiking levels and 63.6%-93.9% and 1.6%-8.1% for 6 quinolones at 5.0 ng/L and 20.0 ng/L spiking levels, respectively. The detection limits were 20.0 ng/L for 4 tetracyclines and 0.4 ng/L for 6 quinolones. The method has been successfully applied to the survey of 10 target antibiotic residues in Jiulong River estuary, Fujian.
    Determination of polybrominated diphenyl ethers in pine needles using ultrasonic-assisted extraction and gas chromatography-negative chemical ionization-mass spectrometry
    CHEN Chang’er, ZHAO Hongxia, XIE Qing, CHEN Jingwen
    2009, 27 (1):  59-62. 
    Abstract ( 2397 )   [Full Text(HTML)] () PDF (270KB) ( 612 )  
    A method for the determination of polybrominated diphenyl ethers (PBDEs) in pine needles was developed. Ultrasonic-assisted extraction (UAE) was employed with n-hexane-acetone (1∶1, v/v), and concentrated H2SO4 and an alumina column were used for cleaning-up the extract of pine needles. The final extract was identified and quantified for the 8 PBDE congeners(BDE-28, 47, 99, 100, 153, 154, 183, and 209) by gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS) with internal standard method in the selective ion monitoring (SIM) mode. The recoveries of the spiked standards ranged from 83.8% to 107.5%. The instrumental detection limits for tri- to hepta-BDEs (BDE-28, 47, 99, 100, 153, 154 and 183) were in the range of 0.152-0.770 pg, and for BDE-209 was 11.1 pg. The method detection limits for the above-mentioned PBDEs were 3-15 pg/g wet weight and 222 pg/g wet weight, respectively. The results indicate that the method has high sensitivity, satisfactory recovery and good reproducibility. BDE-209 was found to be the dominant congener (82.3% of the total of 8 PBDEs), and BDE-47 was the major congener among the lower brominated congeners.
    Determination of trichlorobenzenes in water-based cutting fluids and wastewater of machining using dispersive liquid-liquid microextraction-gas chromatography/mass spectrometry
    SHEN Haoyu, ZHAO Yonggang, HUAI Mingmin, JIANG Hailiang
    2009, 27 (1):  63-68. 
    Abstract ( 2338 )   [Full Text(HTML)] () PDF (664KB) ( 708 )  
    The determination of trichlorobenzenes (TCBs) in water-based cutting fluids and wastewater of machining has been carried out. A gas chromatography/mass spectrometry (GC/MS) method with selected ion monitoring (SIM) mode was employed. The target analyte was extracted from the matrix using dispersive liquid-liquid microextraction. Comparing with gas chromatography/electronic capture detection (GC/ECD) coupled with traditional sample preparation procedures, e.g. head-space extraction, liquid-liquid extraction and solid-phase extraction, the present method was accurate with broader linear range, better enrichment property, better replicability, easier to be operated and less interference. Overall recoveries were 94.7%-104.3% with the relative standard deviations (RSDs) of at 2.3%-7.8%. The detective limits for 1,3,5-, 1,2,4- and 1,2,3-trichlorobenzene were 2.0, 6.0 and 3.0 μg/L, respectively. The parameters, such as the nature and volume of extraction solvent, dispersive solvent, extraction time and salt effect, were studied and optimized. Some important factors, e.g., the concentration of common used additives in water-based cutting fluids, which may affect the recoveries and replicabilities for the determination of trichlorobenzenes, have been investigated. The result showed that no significant effects have been observed when the concentrations of NaNO2 and polyethylene glycol (PEG) were up to 1.0 %. The present method has been applied for the determination of the trichlorobenzenes in 4 real samples. The result showed that two of them were found to contain these trichlorobenzenes. The TCBs in the samples were 0.15-1.67 mg/L.
    Simultaneous determination of ten organotin compounds in polyvinyl chloride plastics using gas chromatography-mass spectrometry
    LI Ying, LI Bin, LIU Li, ZHANG Chen, WU Jingwu, LIU Zhihong, LI Xintian
    2009, 27 (1):  69-73. 
    Abstract ( 2724 )   [Full Text(HTML)] () PDF (342KB) ( 990 )  
    A rapid and effective gas chromatography coupled with mass spectrometry method has been developed systematically and studied for the simultaneous determination of 10 organotin compounds, dibutyltin-dichloride (DBT), n-butyltin-trichloride (MBT), triethyltinchloride (TET), fentin-chloride (TPhT), chlorotributylstannane (TBT), tri-n-propyltinchloride (TPrT), diphenyltin-dichloride (DPhT), tetrabutyltin (TeBT), di-n-octyltin-dichloride (DOT), phenyltin trichloride (MPhT)), in polyvinyl chloride (PVC) plastics. The PVC sample was dissolved with tetrahydrofuran and the polymer in the sample was precipitated with methanol, and then the target compounds were derivatized with sodium tetraethylborate and extracted with hexane under ultrasonication. The qualitative and quantitative analysis were carried out by GC-MS and the total ion chromatogram and selected ion chromatogram were obtained. The derivatization and extraction conditions, such as the derivatization time, derivatization pH value, dosages of derivatization reagent and precipitation reagent were optimized. The good linearities, recoveries and precisions were obtained. The linearity ranges were 0.5-50 mg/L. The linearity correlation coefficients of 10 organotin compounds were between 0.9978 and 0.9997. The average recoveries were 84.23%-109.1% with relative standard deviations of 4.24%-10.75%. The established method has been successfully applied to the determination of organotin compounds in PVC plastics.
    Simultaneous determination of prilocaine and lidocaine in transdermal receiving fluid using gas chromatography-mass spectrometry
    YANG Yingying, ZHANG Wensheng, YE Liming
    2009, 27 (1):  74-77. 
    Abstract ( 2838 )   [Full Text(HTML)] () PDF (273KB) ( 652 )  
    A method for the simultaneous determination of prilocaine and lidocaine in vitro percutaneous absorption liquid using gas chromatography-mass spectrometry (GC-MS) has been developed. Ropivacaine served as the internal standard. The sample was alkalified with sodium hydroxide and a single-step liquid-liquid extraction with ethyl acetate. Selected ion monitoring (SIM) method was applied for the detection. Using the method to determine prilocaine and lidocaine in the rapid transdermal study. Prilocaine and lidocaine have good linear relationships in the concentration of 0.016-50.0 mg/L. The recoveries of prilocaine and lidocaine ranged from 85.3% to 109.7%, and the relative standard deviations of intra-day and inter-day were less than 10%. The limits of detection were 3 μg/L for prilocaine and 2 μg/L for lidocaine. This assay was time-saving, alternative and sensitive. It was suitable for the analysis of samples collected from the study on in vitro percutaneous absorption.
    Determination of chlorpyrifos and its metabolite in vegetables using gas chromatography-tandem mass spectrometry
    LING Yun, WANG Han, YONG Wei, CHU Xiaogang
    2009, 27 (1):  78-81. 
    Abstract ( 2496 )   [Full Text(HTML)] () PDF (344KB) ( 1283 )  
    A method was developed for the determination of chlorpyrifos and its metabolite3,5,6-trichloro-2-pyridinol (TCP) in vegetables using gas chromatography-tandem mass spectrometry (GC-MS/MS). The sample was extracted with acetone. After the concentration, TCP was derivatized with N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA). The purification was performed using a florisil solid-phase extraction cartridge. The analyte was detected by triple quadrupole MS in multi-reaction monitoring mode. An internal standard method was used for the quantification of chlorpyrifos, the limit of quantification was 1 μg/kg, and the recoveries were in the range of 75.57%-106.41% with the relative standard deviations (RSDs) of 8.33%-17.58%. An external standard method was used for the quantification of TCP, the limit of quantification was 0.5 μg/kg, and the recoveries were in the range of 69.11%-108.43% with the RSDs of 5.20%-19.42%. The good linear relationships were obtained in the range of 2-100 μg/L for the both target analytes. The method can be applied for the determination of chlorpyrifos and its metabolite in vegetables.
    Determination of bifenthrin residue in plant-based foods using gas chromatography-mass spectrometry
    DONG Zhenlin, YANG Chunguang, XUE Dafang, ZHANG Huayi, PANG Yanhua
    2009, 27 (1):  82-85. 
    Abstract ( 2440 )   [Full Text(HTML)] () PDF (169KB) ( 621 )  
    A method was established for the determination of bifenthrin residue in 8 plant-based foods using gas chromatography-mass spectrometry (GC-MS). The grain was extracted by acetonitrile and cleaned up with gel permeation chromatography (GPC) combined with a Florisil solid-phase extraction (SPE) cartridge, while the vegetables and fruits were extracted by ethyl acetate and cleaned up only with a Florisil SPE cartridge. Most of the lipids in the extract for the grain were eliminated by GPC, prior to SPE cleanup. The cleaned extract was analyzed by GC-MS with electron impact (EI) source in selective ion monitoring (SIM) mode. The detection limit was 5 μg/kg (S/N=10). There was a good linearity within the range of 0.005-0.5 mg/L with the correlation coefficient of 0.9999. The recoveries were between 74%-99% with the relative standard derivations of less than 13% at the spiking levels of 0.005, 0.04 and 0.1 mg/kg
    Determination of clopidol residues in chicken muscle by gas chromatography-mass spectrometry
    LIU Xiangguo, SU Yijuan, FANG Binghu, DING Huanzhong, HE Limin, ZENG Zhenling, CHEN Zhangliu
    2009, 27 (1):  86-90. 
    Abstract ( 2294 )   [Full Text(HTML)] () PDF (497KB) ( 590 )  
    A confirmative method to determine clopidol residues in chicken muscle by gas chromatography-mass spectrometry (GC-MS) was developed. The analyte was extracted with acetonitrile, and then purified with an Alumina-B cartridge column. The drug was derived at 80 ℃ for 60 min with Sylon BFT, and more toluene was added and then applied to GC-MS. The mass spectral characteristics of trimethylsilyl derivative of clopidol were interpreted, and selected ion monitoring (SIM) mode was performed at m/z 212, 214, 248 and 263. The clopidol was qualitatively identified by the ratio of relative abundance of the selected ions and determined quantitatively by SIM mode at m/z 248. In the meantime, the matrix effect was evaluated. The range of linearity was 5.0-500 μg/L with the correlation coefficients better than 0.998, and the detection limit was 0.5 μg/kg (S/N=3) for clopidol. The average recoveries from chicken muscle fortified at 5, 10 and 20 μg/kg were 77.0%, 84.5% and 89.4%, respectively, and the relative standard deviations (RSD) were less than 6.9%. The established method is simple, sensitive and reproducible for the identification and quantification of clopidol residues in chicken muscle tissue.
    Determination of 12 azole fungicide residues in beans and corn by offline disperse solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry
    SHEN Weijian, GUI Qianwen, YU Keyao, SUN Ningning, ZHAO Zengyun,
    2009, 27 (1):  91-95. 
    Abstract ( 2660 )   [Full Text(HTML)] () PDF (394KB) ( 699 )  
    A confirmatory method is proposed for the determination of 12 azole fungicide residues in beans and corn with the technique of offline disperse solid phase extraction (DSPE) and gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The pesticides interested were extracted from the samples with acetonitrile containing 1% acetic acid and simultaneous liquid-liquid partitioning formed by adding anhydrous magnesium sulfate plus sodium acetate followed by a simple cleanup step known as dispersive solid-phase extraction. The aliquot was determined and confirmed by GC-NCI/MS using external standard method. The recoveries of all pesticides were between 70% and 130% at the three spiked levels, 10 μg/kg, 20 μg/kg and 40 μg/kg. The relative standard deviations were less than 13.9%. The linearity of method was good from 50 to 1000 μg/L. The limits of quantification (LOQ) were less than 8 μg/kg. The method is selective with no interference and is suitable for the confirmatory of pesticide residues in beans and corn.
    Characteristics of subunit types and isoelectric points in four pancreas ferritins by electrophoresis and mass spectrometry
    LIN Zhichao, LIN Qing, ZHU Feng, HUANG Heqing,
    2009, 27 (1):  96-101. 
    Abstract ( 2416 )   [Full Text(HTML)] () PDF (2499KB) ( 563 )  
    The pancreas ferritins from chickens, ducks, cattle and pigs were isolated by thermal denaturation, ammonium sulphate fractionation and DEAE-52 cellulose anion exchange chromatography separately, in order to obtain the characteristics both subunit types and isoelectric points. Four ferritins such as chicken pancreas ferritin (ChPF), duck pancreas ferritin (DPF), cattle pancreas ferritin (CaPF), and pig pancreas ferritin (PPF) showed different mobility in polyacrylamide gel electrophoresis (PAGE). The relative molecular masses (Mr) of these ferritin were indicated to be Mr (ChPF)>Mr (DPF)>Mr (CaPF)>Mr (PPF), which are all bigger than that in horse spleen ferritin (HSF). Sodium dodecyl sulfate (SDS)-PAGE results indicate that ChPF, DPF, CaPF and PPF consist of H and L subunits, showing different ratios of H/L subunits. Two subunit types in the ferritin were further identified by peptide-mass fingerprinting (PMF) technology. The four ferritins such as ChPF, DPF, CaPF and PPF in denatured-isoelectric focusing (IEF) gel show the subunit polymers containing from 3 to 6 with different pI values, respectively. These phenomena reveal the complicated interactions and different polymers between H and L subunits in the ferritins. There are differences both interaction intensities and polymers in the ferritin subunits coming from different mammals. These heterogeneity may response to the rate of iron release in ferritins and to the detoxification requirement of iron in animals in vivo.
    Preconcentration and separation of DNA fragments based on microchip electrophoresis
    XU Zhongqi, HIROKAWA Takeshi
    2009, 27 (1):  102-106. 
    Abstract ( 2220 )   [Full Text(HTML)] () PDF (6267KB) ( 583 )  
    An online preconcentration method, electrokinetic supercharging (EKS) was used for the enrichment of DNA fragments based on microchip electrophoresis (MCE). EKS is a process that combines electrokinetic injection (EKI) with transient isotachophoresis (tITP). The results demonstrated that the large volume of low concentration sample could be introduced, preconcentrated, and eventually separated on a single channel microchip with the whole length of 40.5 mm. The limit of detection (S/N=3) of DNA fragments was around 0.07 mg/L, effectively improved 40-fold by EKS preconcentration with the normal UV detection at 260 nm. Some important parameters for enhancing preconcentration and qualitative analysis were examined.
    Simultaneous determination of seven effective components in Houpuwenzhong capsules using high performance liquid chromatography
    DING Xiaoju, ZHAO Yunli, GAO Xiaoxia, TANG Qian, LI Lin, YU Zhiguo
    2009, 27 (1):  107-110. 
    Abstract ( 2214 )   [Full Text(HTML)] () PDF (345KB) ( 524 )  
    A high performance liquid chromatographic (HPLC) method was developed for the simultaneous determination of seven effective components in Houpuwenzhong capsules. The separation was performed on a Scienhome C18 column (250 mm×4.6 mm, 5 μm) with methanol-acetonitrile-0.06% phosphonic acid (38∶27∶35, v/v/v) as the mobile phase at a flow rate of 1.0 mL/min and 30 ℃. The detective wavelength was set at 235 nm. There were good linear relationships between the mass concentrations and the peak areas of alpinetin, glycyrrhizic acid, honokiol, cardamonin, costunolide, dehydrocostus lactone and magnolol in the ranges of 0.885-17.7, 107-2140, 8.85-17.7, 1.035-20.7, 4.85-97, 5.9-118 and 17.5-350 mg/L, respectively. The recoveries were 96.9%-101.1%, 96.0%-100.5%, 100.3%-100.8%, 97.7%-101.4%, 100.4%-102.3%, 96.0%-102.3% and 96.2%-100.6%, respectively. This method is rapid, simple and suitable for the quality control of Houpuwenzhong capsules.
    Technical Notes
    Simultaneous determination of artificial sweeteners in beverage by ultra performance liquid chromatography
    JI Chao, SUN Yanyan, LI Xiuqin, CHU Xiaogang, CHEN Zhengxing
    2009, 27 (1):  111-113. 
    Abstract ( 2661 )   [Full Text(HTML)] () PDF (208KB) ( 782 )  
    An ultra performance liquid chromatographic (UPLC) method for the simultaneous separation and determination of four artificial sweeteners (sodium saccharin, aspartame, acesulfame and neotame) in a single injection was developed. The separation was performed on an ACQUITY UPLCTM BEH C18column with gradient program and detection at 220 nm. The good linearities between the concentrations of all analytes and peak area responses were achieved over the range from 0.5 to 20.0 mg/L. The average recoveries in samples were 80.5%-95.2% with the relative standard deviations of 0.50%-8.7%. The method has been successfully applied to the determination of the four sweeteners in drinks and powdered tabletop sweeteners.
    Determination of four acetophenones in Radix Cynanchi bungei by high performance liquid chromatography-photodiode array detection
    SUN Yinshi, LIU Zhengbo, WANG Jianhua, WANG Ying, ZHOU Hongying, ZHANG Wenli, WANG Jun, QIAO Gui
    2009, 27 (1):  114-116. 
    Abstract ( 2094 )   [Full Text(HTML)] () PDF (193KB) ( 524 )  
    A high performance liquid chromatographic (HPLC) method was developed for the determination of four acetophenones, namely 4-hydroxyacetophenone (Ⅰ), 2,5-dihydroxyacetophenone (Ⅱ), baishouwubenzophenone (Ⅲ) and 2,4-dihydroxyacetophenone (Ⅳ), in Radix Cynanchi bungei. The HPLC with photodiode array (PDA) detection was carried out on a Symmetry-C18 (4.6 mm×250 mm, 5 μm) column with CH3OH-H2O (26∶74, v/v) as the mobile phase at the flow rate of 1.0 mL/min and 30 ℃. The compounds Ⅰ, Ⅲ, Ⅳ were monitored at 280 nm, and the compound Ⅱ was at 224 nm. Four acetophenones (Ⅰ-Ⅳ) had good linearities (r=0.9996-0.9999) at the ranges of 0.080-0.560 μg, 0.080-0.560 μg, 0.100-0.700 μg and 0.092-0.644 μg, respectively. The average recoveries were from 98.0% to 104.0% with relative standard deviations (RSD) ranging from 0.8% to 2.6%. The method is of quick, simple and accurate. The method can be used for the quality control of this product
    Determination of glucosamine hydrochloride in health foods using high performance anion exchange chromatography
    ZHANG Siwei, ZHENG Bo, ZOU Xiaoli, ZENG Hongyan, SUN Chengjun, CHEN Xin
    2009, 27 (1):  117-119. 
    Abstract ( 2566 )   [Full Text(HTML)] () PDF (156KB) ( 679 )  
    The method for the analysis of glucosamine hydrochloride in health foods using high performance anion exchange chromatography was established. The determination of glucosamine hydrochloride was performed on an AminoPac PA10 column (2 mm×250 mm) with a pulse amperometric detector with an Au working electrode and an Ag/AgCl reference electrode. The linear range was 0.05-10.0 mg/L, and the detection limit was 0.012 mg/L. The relative standard deviations for the determination of the standard and a sample were 0.69% and 1.38%, respectively. The satisfactory results were obtained for the analysis of health food samples with the proposed method, and the spiked recovery was 96.6%-105.2%. In comparison with the national standard method, the relative deviations of the determination results were -1.4%-1.0%. The method is sensitive and precise. One analysis can be completed within 5 min. This method was available for the determination of glucosamine hydrochloride in health foods.
    An attempt of multiple-electro-development on planar electrochromatography
    GE Zhaohui, WANG Dongyuan, CUI Yongquan, JIANG Yang
    2009, 27 (1):  120-123. 
    Abstract ( 1888 )   [Full Text(HTML)] () PDF (128KB) ( 505 )  
    A new thin layer plate, the RP-C18 sintered plate, is described. The electroosmotic flow can be produced without any buffer salts by the carefully controlled bonding degree. It is very convenient and saves a lot of time. Some new development modes and skills can be derived. Based on the firmness of the new plate the operator can brush the mobile phase on the plate directly, which is very simple and fast for wetting the plate and saves much reagent. If the plate becomes dry during the process of planar electrochromatography, the operator can re-wet the plate on the local and then develop it again. Such operation can be repeated many times until the spots are separated completely, so it is called multiple-electro-development. The buffer salt in the mobile phase is abolished, which makes the process of multiple-electro-development possible. As the bonding degree descends, the effect of the plate is not as good as before, but the total separation efficiency and the potential increase due to the multiple-electro-development.