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Chinese Journal of Chromatography
2010, Vol. 28, No. 7
Online: 28 July 2010

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Preparation and high performance liquid chromatographic separation of casein peptides CAI Huanxin, YIN Baoru, YAO Ping 2010, 28 (7):  637-643.  DOI: 10.3724/SP.J.1123.2010.00637 Abstract ( 2970 )   [Full Text(HTML)] () PDF (265KB) ( 648 )   A preparative reversed-phase high performance liquid chromatography-electrospray ionization mass spectrometry (RP-HPLC/ESI-MS) method to obtain low cost casein peptides was developed. Casein was hydrolyzed by trypsin and the hydrolysate was analyzed by RP-HPLC/ESI-MS firstly. The gradient elution program in an analytical column was optimized to achieve a better separation. The effect of pH of the mobile phase on the separation was also investigated. Then, the optimal analytical conditions were applied in a preparative column directly. In each loading of the hydrolysate, several pure peptide fractions were collected automatically by the inductions of ultraviolet absorbance and mass spectrometry signals together. The process is simple and effective. The influence of the loading amount in a preparative column was investigated intensively. For the collection consisting of hydrophilic peptides that were poorly separated in the primary process, secondary separation was performed. By changing the gradient elution, several different pure peptides were obtained.

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Plasma metabonomics study of systemic lupus erythematosus based on liquid chromatography-mass spectrometry YU Ying, CAO Yi, CHEN Yimin, WEN Chengping, XU Zhiliang 2010, 28 (7):  644-648.  DOI: 10.3724/SP.J.1123.2010.00644 Abstract ( 2848 )   [Full Text(HTML)] () PDF (235KB) ( 761 )   A rapid resolution liquid chromatography coupled with quadrupole-time of flight mass spectrometry method (RRLC-Q-TOF/MS) was used to analyze metabolic fingerprint of the plasma samples from systemic lupus erythematosus (SLE) patients. Supervised pattern recognition methods combined with orthogonal signal correction partial least square-discriminate analysis (OSC-PLS-DA) were used to process the metabolic data. A nice distinction between SLE patients and healthy control group was observed. Further, ten ions, which had a significant contribution to classification, had been selected from metabolic profiles of SLE patients. The ten ions were identified and belong to seven metabolic biomarkers. It was shown that there were abnormal metabolisms of amino acids, phospholipids and porphyrin in SLE patients. It provided a scientific basis for the monitoring and diagnosis of SLE. These results will benefit the early intervention and treatment of SLE and the research of the mechanism of pathogenesis.

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Determination of chlordimeform and its metabolite residues in honey using liquid chromatography-tandem mass spectrometry YI Xionghai, HAN Li, YANG Huiqin, FAN Xiang, ZHU Jian, GUO Dehua 2010, 28 (7):  649-653.  DOI: 10.3724/SP.J.1123.2010.00649 Abstract ( 2640 )   [Full Text(HTML)] () PDF (205KB) ( 537 )   A liquid chromatography-tandam mass spectrometry (LC-MS/MS) method was developed for the determination of chlordimeform and its metabolite (4-chloro-o-toluidine) residue in acacia honey, chaste honey, comb honey, multifloral honey and wild honey. The samples were dissolved and diluted with sodium hydroxide solution, and cleaned up by a Waters Oasis HLB solid phase extraction column. The separation was performed on an Agilent XDB-C18 column with gradient elution using 0.1% formic acid solution and acetonitrile. The residues of chlordimeform and its metabolite were determined by electrospray ionization-tandem mass spectrometry, and quantified by the method of matrix-matched external standard. The calibration curves for chlordimeform and its metabolite showed good linearity in the range of 2.5~250 μg/L with the correlation coefficients (r) higher than 0.999. The limit of quantification was 5 μg/kg, and the limit of detection was 2.5 μg/kg. The recoveries of chlordimeform and 4-chloro-o-toluidine in honey at the spiked levels of 5, 10 and 20 μg/kg were in the ranges of 75.8%~113.8% and 85.6%~114.3%, respectively. The relative standard deviations were 4.8%~10.2% and 4.7%~9.1%, respectively. The method can meet the requirements for the determination of chlordimeform and 4-chloro-o-toluidine in honey for import and export inspection.

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Simultaneous determination of 103 pesticide residues in cabbages and apples using programmable temperature vaporizer-based large volume injection by gas chromatography-negative chemical ionization mass spectrometry DONG Jing, PAN Yuxiang, QIN Yaping, L Jianxia, YU Qiongwei 2010, 28 (7):  654-663.  DOI: 10.3724/SP.J.1123.2010.00654 Abstract ( 2851 )   [Full Text(HTML)] () PDF (495KB) ( 486 )   A gas chromatography-mass spectrometric （GC-MS） method has been established for the simultaneous determination of 103 pesticide residues in cabbages and apples using programmable temperature vaporizer-based large volume injection (PTV-LVI) and negative chemical ionization (NCI). It was found that much lower detection limits for the investigated pesticides can be obtained. Prior to GC-NCI/MS analysis, the optimized parameters of PTV-LVI were as follows: inlet temperature was set at 45 ℃, split vent flow rate was 20 mL/min, evaporation time was 1 min and evaporation temperature was set at 60 ℃. The volume of injection was 10 μL. Co-extractives were removed from the acetonitrile extracts using solid phase extraction with octadecyl (200 mg) and primary secondary amine (100 mg) sorbents. Matrix matched calibration solutions were used for all the analyses. To evaluate performance of the method, validation experiments were carried out in cabbages and apples at two spiking levels (5 and 10 μg/kg). The average recoveries ranged from 58.5% to 113.2%, and the relative standard deviations (RSDs, n=6) were in the range of 3.3%~14.5%. The limits of detection (S/N=3) were less than 5 μg/kg for all the pesticides. The results show that this method is simple, rapid, sensitive and specific. It is appropriate for the simultaneous identification and quantification of the multi-residues in cabbages and apples.

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Determination of dichlorobromomethane in water by headspace-trap gas chromatography/mass spectrometry WANG Pingya, ZHAO Hua, ZHOU Yong, XU Zhenjian, DAI Yifei, ZHANG Weiying 2010, 28 (7):  664-667.  DOI: 10.3724/SP.J.1123.2010.00664 Abstract ( 2824 )   [Full Text(HTML)] () PDF (150KB) ( 644 )   A novel method was developed for the determination of dichlorobromomethane in water using headspace-trap gas chromatography/mass spectrometry (GC/MS). Three parameters of headspace-trap including thermostatic temperature, time and cycle number were optimized by orthogonal experiment analysis. Dichlorobromomethane in water samples was analyzed under the optimized conditions of 70 ℃ and 20 minutes with the cycle number of two. The results showed that the calibration curve was linear in the range of 0.1~10.0 μg/L, and the correlation coefficient was 0.9991. The detection limit was 0.03 μg/L. The average recovery was 83.1%~111.3% with the relative standard deviation (RSD) not more than 5.2% (n=6). This method is rapid, sensitive and reproducible for the routine detection of the low concentration of dichlorobromomethane in water.

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Analysis of fatty acid composition of Ulva pertusa Kjellm by gas chromatography/mass spectrometry LOU Qiaoming, XU Jie, WANG Yuming, XUE Changhu, SUN Zhaomin 2010, 28 (7):  668-672.  DOI: 10.3724/SP.J.1123.2010.00668 Abstract ( 2774 )   [Full Text(HTML)] () PDF (190KB) ( 635 )   A method of gas chromatography/mass spectrometry (GC/MS) was established to determine the fatty acids of Ulva pertusa Kjellm. The total lipids of Ulva pertusa Kjellm were extracted using Folch method, derivatized with HCl-CH3OH solution, and analyzed by GC/MS. The fragmentation patterns and mass spectrometry characteristics of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids were analyzed and concluded by regular patterns of organic mass spectrometry. According to the database index and standard controls, twenty-four fatty acid components in Ulva pertusa Kjellm were identified, and the contents of 9,12,15-octadecatrienoic acid, 4,7,10,13-hexadecatetraenoic acid and 6,9,2,15-octadecatetraenoic acid accounted for 45.14% of the total fatty acids. The qualitative results of fatty acids in Ulva pertusa Kjellm show that it is very useful in identifying fatty acid methyl esters by characteristic ions, especially polyunsaturated fatty acid methyl esters.

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Simultaneous determination of cocaine and its metabolite ecgonine methyl ester in human blood using microwave extraction-gas chromatography WANG Xiaobo, YE Nengsheng, WANG Jifen, GU Xuexin 2010, 28 (7):  673-676.  DOI: 10.3724/SP.J.1123.2010.00673 Abstract ( 2663 )   [Full Text(HTML)] () PDF (148KB) ( 543 )   A method was developed for the simultaneous determination of cocaine (COC) and its metabolite ecgonine methyl ester (EME) in human blood using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). The blood sample was prepared by microwave extraction (MWE). The optimal parameters of MWE were as follows: 6 mL of chloroform-isopropanol (9:1, v/v) mixture as extraction solvent, the pH value of the sample was adjusted at 10.0 with 0.05 mol/L Na2CO3-NaHCO3 buffer, the extraction was performed at 40 ℃ for 6 min. The COC and EME in the extract were qualified using GC-MS and quantitated using GC-FID. The average recoveries of COC and EME were from 79.91% to 99.85%, the relative standard deviations were less than 3.10%, and the limits of detection (LOD) were 60 and 40 mg/L, respectively. In the method COC and EME were detected without derivatization. The method is rapid, accurate and sensitive, and can be used for the simultaneous determination of COC and EME in blood samples.

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Simultaneous determination of berberine, palmatine, matrine, catechin and baicalin in Funing Shuan by micellar electrokinetic capillary chromatography-electrospray ionization mass spectrometry ZENG Yongfang, HUO Peng, XU Yuanjin, 2010, 28 (7):  677-681.  DOI: 10.3724/SP.J.1123.2010.00677 Abstract ( 3136 )   [Full Text(HTML)] () PDF (185KB) ( 529 )   A method for the simultaneous determination of berberine, palmatine, matrine, catechin and baicalin in Funing Shuan was established using micellar electrokinetic capillary chromatography-electrospray ionization mass spectrometry (MEKC-ESI MS). The compounds were separated on an uncoated capillary (80 cm×50 μm) with the operating voltage of 25 kV and the running buffer of 40 mmol/L lauric acid-100 mmol/L ammonia mixture containing 25% acetonitrile (pH 9.5). The baseline separation of the five compounds was achieved within 16 min with a satisfactory repeatability and sensitivity. The solution of 50% 2-propanol/water solution (containing 3 mmol/L acetic acid) was used as the sheath liquid for the ESI MS analysis. The results showed that the linear ranges for berberine, palmatine, matrine, catechin and baicalin were 0.03~15, 0.05~15, 0.2~250, 1.5~300 and 2.0~500 mg/L, respectively, and the detection limits were 0.01, 0.02, 0.05, 0.5 and 0.6 mg/L, respectively. The average recoveries of the five components were between 94.0%~104.0% with the relative standard deviations (RSDs) of 0.3%~3.2%. The developed method is simple, rapid, and accurate, and it is suitable for the routine analysis of the five effective components in Funing Shuan.

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A novel capillary electrophoretic method for protein determination using bicinchoninic acid-Cu+colorimetric reaction MENG Qingwei, GUO Lei, SHEN Rui, XIE Jianwei 2010, 28 (7):  682-687.  DOI: 10.3724/SP.J.1123.2010.00682 Abstract ( 2875 )   [Full Text(HTML)] () PDF (228KB) ( 594 )   A new rapid, sensitive method for protein determination using capillary electrophoresis and specific colorimetric reaction of bicinchoninic acid (BCA) was established, assisted by microwave incubation. With 60 mmol/L boric acid buffer (pH 9.5) and inclusion additive of β-cyclodextrin, the complex of BCA-Cu+ and free BCA molecules were efficiently separated. The peak intensity of BCA-Cu+was higher than those of native proteins about two orders of magnitude at a low wavelength of 200 nm. The linear ranges of this method were from 2 to 200 mg/L for transferrin, and 2 to 100 mg/L for ricin. The limits of detection for transferrin and ricin were 0.33 and 0.37 mg/L, respectively. This method was also successfully applied in the determination of some ricin samples in the First International Proficiency Test on the quantification of ricin.

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Determination of binding domains of paeonol on immobilized human serum albumin by high-performance affinity chromatography YU Xue, ZHANG Juncai, WEI Yinmao 2010, 28 (7):  688-692.  DOI: 10.3724/SP.J.1123.2010.00688 Abstract ( 2671 )   [Full Text(HTML)] () PDF (179KB) ( 518 )   High-performance affinity chromatography was used to investigate the binding of paeonol (PAE) to immobilized human serum albumin (HSA) under the condition of pH 7.4 and temperature of 37 ℃. Self-competition zonal elution indicated that there was only one major binding site on HSA for PAE. The association constant of PAE with HSA was 4.84×103 L/mol. Competition studies based on zonal elution were carried out between PAE and various probes which have been known to interact with several major and minor sites on HSA. PAE was found to have direct competition with L-tryptophan. The results indicated that PAE interacted with Sudlow site II on HSA. The thermodynamic analysis indicated that the main force between the paeonol and HSA was hydrogen bond or van der Waals force.

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Thermodynamic properties of novel phenylene-bridged periodic mesoporous organosilica as high performance liquid chromatographic stationary phase WU Liping, LIAN Dong, ZHANG Qinghe, LI Hongmei 2010, 28 (7):  693-696.  DOI: 10.3724/SP.J.1123.2010.00693 Abstract ( 2687 )   [Full Text(HTML)] () PDF (187KB) ( 421 )   The thermodynamic properties of spherical phenylene-bridged periodic mesoporous organosilica (PMOs) as high performance liquid chromatographic stationary phase were investigated and compared with commercial grafted C18 and phenyl stationary phases. The retention behavior of several compounds of polycyclic aromatic hydrocarbons (PAHs) was investigated. The thermodynamic parameters of transfer from mobile phase to stationary phase were discussed. The results showed that the enthalpy-entropy compensation effect does not exist for homemade phenylene-bridged PMOs. The retention mechanism of solutes on the prepared stationary phase involves synergistic interaction of hydrophobic, π-π and inclusion interactions, which is different with that on the commercial stationary phases.

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Characterization of the surface tension and solubility parameter of epoxy resin by using inverse gas chromatography SHI Fenghui , DAI Zhishuang, ZHANG Baoyan 2010, 28 (7):  697-701.  DOI: 10.3724/SP.J.1123.2010.00697 Abstract ( 3178 )   [Full Text(HTML)] () PDF (202KB) ( 512 )   Inverse gas chromatography (IGC) was used to measure the surface tension and solubility parameter of E51 epoxy resin in this work. By using the Schultz method, decane, nonane, octane and heptane were chosen as the neutral probes to calculate the dispersive surface tensions (γD). Based on the Good-van Oss equation, the specific surface tension (γSP) of E51 epoxy resin was calculated with the acidic probe of dichloromethane and the basic probe of toluene. The results showed that the γD and γSP of the E51 resin decreased linearly with the increase of temperature. According to the Flory-Huggins parameters (χ) between the resin and a series of probes, the solubility parameters (δ) of E51 resin at different temperatures were estimated using the method developed by DiPaola-Baranyi and Guillet. It was found that the values of δ of the E51 resin were 11.78, 11.57, 11.48 and 11.14 MPa1/2 at 30, 40, 50 and 60 ℃, respectively. The dispersive component (δD) and the specific component (δSP) of solubility parameter at different temperatures of the E51 resin were investigated according to the relationships between surface tension, cohesion energy and solubility parameter. The results showed that the values of δD were higher than those of δSP for the epoxy resin, and both of them decreased with the increase of temperature.

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Simultaneous determination of ammonium and six alkylamines in cosmetics by ion chromatography ZHONG Zhixiong, LI Gongke, ZHU Binghui, LUO Zhibin, WU Ximei 2010, 28 (7):  702-707.  DOI: 10.3724/SP.J.1123.2010.00702 Abstract ( 2943 )   [Full Text(HTML)] () PDF (202KB) ( 786 )   A method for the simultaneous determination of ammonium and six alkylamines in cosmetic products by ion chromatography (IC) was developed. The sample pretreatment process and the separation resolution of chromatography were investigated. The samples were extracted by 100 mmol/L acetic acid-20%(v/v) acetonitrile solution at room temperature, and then solid phase extraction (SPE) column was used to eliminate the interferences. The influences of pH value, organic solvent and coexisted ions were investigated. The separation was carried out on IonPac CS17 (250 mm×4 mm)analytical column and IonPac CG17 (50 mm×4 mm)guard column using 1.5~15 mmol/L methanesulfonic acid and 0.5%~5%(v/v) acetonitrile gradient elution at a flow rate of 1.0 mL/min at 24 ℃, coupled with suppressed conductivity detector. Under the optimum conditions, a measurement could be completed less than 26 min. The linearity ranged from 0.3 to 15 mg/L, the detection limits and the quantification limits were in the ranges of 2.1~7.9 mg/kg and 7~26 mg/kg, respectively. The method was successfully employed for the determination of ammonium, methylamine, dimethylamine, trimethylamine, ethylamine, propylamine and butylamine in samples including cleaning, body lotion, skin-bleaching, sun block, marcel, hair dye and pilatory cosmetics with the recoveries of 80.2%~109.2% and the relative standard deviations (RSDs) of 0.5%~3.1%. The method offered high selectivity, sensitivity, and gave satisfactory results for real sample analysis.

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Simultaneous determination of trifluoroacetate, tetrafluoroborate and halide ions in ionic liquid by ion chromatography LI Siwen, ZHANG Xiaodong, YU Hong 2010, 28 (7):  708-711.  DOI: 10.3724/SP.J.1123.2010.00708 Abstract ( 2835 )   [Full Text(HTML)] () PDF (159KB) ( 733 )   A method was developed for the simultaneous determination of trifluoroacetate, tetrafluoroborate and halide ions (F~, Cl~, Br~) by ion chromatography with direct conductivity detection. The chromatographic separation was performed on a Shim-pack IC-A3 anion-exchange column with potassium biphthalate, phthalic acid+tris(hydroxymethyl)-aminomethane, and p-hydroxybenzoic acid+tris(hydroxymethyl)-aminomethane+boric acid as eluent, separately. The effects of the nature of eluent, eluent concentration, acetonitrile concentration and column temperature on the separation and the retention factors of the anions were investigated. The optimized chromatographic conditions for the determination of the anions were as follows: 1.2 mmol/L potassium biphthalate as eluent, a column temperature of 45 ℃ and a flow rate of 1.0 mL/min. Under the optimal conditions, the anions were baseline separated. Moreover, the symmetries of peaks were better. The limits of detection (S/N=3) for the anions were in the range of 0.01~0.50 mg/L. The relative standard deviations (RSDs) of the chromatographic retention time and peak area for the anions were not more than 0.2% and 1.2% (n=5), respectively. The method has been applied to the determination of trifluoroacetate, tetrafluoroborate and halide ions in ionic liquids. The spiked recoveries of the anions were from 98.0% to 103.2%. The method is simple, accurate and reliable, and has better practicability.

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Determination of maleic hydrazide in vegetables by high performance ion-exclusion chromatography PAN Guangwen, ZHAO Zengyun, HU Zhongyang, YE Mingli 2010, 28 (7):  712-715.  DOI: 10.3724/SP.J.1123.2010.00712 Abstract ( 3198 )   [Full Text(HTML)] () PDF (142KB) ( 440 )   A new method was developed for the determination of maleic hydrazide (MH) in potatoes, onions and garlics by high performance ion-exclusion chromatography (HPIEC). The sample was extracted with acidic methanol, and then analyzed by HPIEC. The analytical column was IonPac ICE-AS1 (250 mm×9 mm) and a mixture of 3 mmol/L formic acid water solution-acetonitrile (70:30, v/v) was used as the eluent at a flow rate of 0.8 mL/min. The detection was performed at 205 nm by an Ultimate 3000 VWD. The quantitative analysis of external standard calibration curves was used. The linear range of the method for MH was 0.006~1.0 mg/L (r=0.9999). The average recoveries were 91%~103% with relative standard deviations (RSDs) less than 3%. The detection limit was 0.002 mg/L for MH. The method is simple, effective, precise, sensitive, reproducible and selective. It can be used to determine the residue of MH in potatoes, onions and garlics.

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Determination of volatiles released from plants by the self-made charcoal trap adsorption device coupled with gas chromatography-mass spectrometry GUO Shuzheng, LIU Sujing, MA Xuanxuan, YANG Cuiyun, ZHOU Shiwei, XIA Chuanhai 2010, 28 (7):  716-719.  DOI: 10.3724/SP.J.1123.2010.00716 Abstract ( 2660 )   [Full Text(HTML)] () PDF (177KB) ( 450 )   The charcoal trap adsorption device was designed and used to adsorb the volatile organic compounds (VOCs) emitted from Ginkgo leaves and Lima beans. The adsorbed VOCs were determined using gas chromatography-mass spectrometry (GC-MS). Compared to solid phase microextraction (SPME), the self-made charcoal trap adsorption device was more advantageous to the enrichment of VOCs from Ginkgo leaves. Additionally, the quantitative analysis of the collected VOCs released from Lima beans was carried out through the addition of internal standard, and the results of the two parallel experiments showed good repeatability. Because the eluent of the charcoal trap can be stored and used in the quantitative analysis as well as parallel experiments, the self-made charcoal trap adsorption device coupled with GC-MS is suitable for laboratory studies of plant volatile organic compounds.

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Rapid determination of patulin in apple juice by tert-butyldimethylsilyl derivatization-gas chromatography-mass spectrometry LI Fengge, YAO Weiqin, TIAN Yanhe, LI Xuewen, ZHANG Hongxia, DOU Hui, ZHU Huiping 2010, 28 (7):  720-723.  DOI: 10.3724/SP.J.1123.2010.00720 Abstract ( 2931 )   [Full Text(HTML)] () PDF (188KB) ( 486 )   A gas chromatography-mass spectrometry (GC-MS) method for the quantitative determination and confirmation of patulin in apple juice by tert-butyldimethylsilyl (TBDMS) derivatization was established. The sample was extracted with ethyl acetate-hexane and an aliquot of the supernatant was cleaned up using mixed-mode solid phase extraction (SPE) cartridge containing C18 and graphitized carbon black (GCB), evaporated to dryness under nitrogen gas and the residue was converted to tert-butyldimethylsilyl derivative which was determined with GC-MS in selected ion monitoring (SIM) mode and external standard method was used for quantitative determination. The linear range was from 0.01 to 1 mg/L. The average recoveries were 88%~98% and relative standard deviations were 5.3%~13.6% in the spiked range of 2~50 μg/kg. The limit of detection was 0.5 μg/kg and the limit of quantification and confirmation was 2 μg/kg. The method is rapid, highly sensitive, accurate, specific, rugged and suitable for the quantitative determination and confirmation of patulin in apple juice.

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Determination of organophosphorus pesticide residues in vegetables by gas chromatography using back-flush technique LI Liang, WU Chunmei, CHEN Jianhang, ZHANG Shaofeng, YE Yufei 2010, 28 (7):  724-728.  DOI: 10.3724/SP.J.1123.2010.00724 Abstract ( 2998 )   [Full Text(HTML)] () PDF (189KB) ( 625 )   The back-flush technique was used in the determination of organophosphorus pesticide residues in vegetables by gas chromatography. The pesticide residues were extracted with acetonitrile and sodium chloride under mechanical shaking, and separated by centrifuging and partitioning. The extract was analyzed by gas chromatograph equipped with a flame photometric detector and a micro fluidic device with back-flush function. The results showed that the 16 organophosphorus pesticides have good linearity within the concentration range of 0.040~3.20 mg/L. The recoveries varied from 75.2% to 111.5%, with the relative standard deviations (RSDs) in the range of 2.8%~10.4%. The detection limits of these target compounds were from 0.003 to 0.01 mg/kg. The application of back-flush technique in this method significantly reduced the cycle time and matrix effect and improved the analysis efficiency.