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Chinese Journal of Chromatography
2013, Vol. 31, No. 2
Online: 28 February 2013

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Recent research progress in magnetic adsorbent DING Lan, WANG Hui 2013, 31 (2):  93-94.  DOI: 10.3724/SP.J.1123.2013.01042 Abstract ( 1124 )   [Full Text(HTML)] () PDF (733KB) ( 477 )

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null YAN Xiaobo1,2*, WU Shaoming1,2, LI Nan3, L Huadong1,2, FU Wusheng1,2* 2013, 31 (2):  95-101.  DOI: 10.3724/SP.J.1123.2012.09002 Abstract ( 1443 )   [Full Text(HTML)] () PDF (786KB) ( 549 )   Fatty acid esters of chloropropanediols are a kinds of newly emerged food contaminants, especially 3-monochloropropane-1,2-diol (3-MCPD) esters that have been detected in many foodstuffs such as infant formula and edible oils at relatively high levels. Based on the Tolerable Dose Intake (TDI) of 3-MCPD, the intake of 3-MCPD from 3-MCPD esters may cause the health risk to human beings. The researches for the analysis of 3-MCPD esters have been carried out in some institutes abroad, but there were only a few in China. This paper reviews the methods for the determination of 3-MCPD esters in fat-rich foods, including the extraction, hydrolysis, the derivatization of 3-MCPD esters, the total amount of 3-MCPD esters and the amounts of monoesters and diesters of 3-MCPD.

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null ZHANG Jiao1,2, ZHOU Lianqi2, TIAN Fang2, ZHANG Yangjun2*, QIAN Xiaohong2 2013, 31 (2):  102-110.  DOI: 10.3724/SP.J.1123.2012.10019 Abstract ( 1051 )   [Full Text(HTML)] () PDF (7706KB) ( 292 )   null

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null WU Yunhui1, ZHOU Shuang2, XU Dunming2* 2013, 31 (2):  111-116.  DOI: 10.3724/SP.J.1123.2012.09037 Abstract ( 1076 )   [Full Text(HTML)] () PDF (1863KB) ( 623 )   A method for the determination of histamine (HIS), tryptamine (TRP), 2-phenylethylamine (2-PHE), putrescine (PUT), cadaverine (CAD), tyramine (TYR), spermidine (SPD), spermine (SPM) in animal-derived foodstuffs was established using high performance liquid chromatography-tandem mass spectrometry. The samples were extracted with acetonitrile-formic acid aqueous solution, and purified with strong cationic exchange (MCX) cartridge. Without derivatization, the eight biogenic amines (BAs) were separated by hydrophilic interaction chromatographic (HILIC) column with the mobile phases of 5 mmol/L ammonium acetate and methanol. The linearities were excellent in the range of 0.001-100 μg/L with the correlation coefficients above 0.99. The limits of detection (LODs, S/N=3) of the method were between 0.001 μg/kg and 1 μg/kg, and the limits of quantification (LOQs, S/N=10) were between 0.003 μg/kg and 5 μg/kg. The recoveries of BAs spiked in eight matrices were between 73.9% and 106.3% at the spiked levels ranged from 0.003 μg/kg to 50 μg/kg. The relative standard deviations (RSDs, n=6) were in the ranges of 5.65%-18.6%. The method can meet the requirements of the daily work for the determination of BAs in animal-derived foodstuffs.

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Determination of seven pesticide residues in bamboo shoots by high performance liquid chromatography-tandem mass spectrometry coupled with solid-phase extraction DING Ming1,2*, ZHONG Donglian1, TANG Fubin1, FANG Wei2 2013, 31 (2):  117-121.  DOI: 10.3724/SP.J.1123.2012.10005 Abstract ( 1373 )   [Full Text(HTML)] () PDF (1769KB) ( 409 )   A simple and efficient method based on solid-phase extraction (SPE) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the determination of butylene fipronil, chlorpyrifos, chlorantraniliprole, fipronil, imidacloprid, indoxacarb and phoxim residues in bamboo shoots. The sample was extracted with acetonitrile and purified by a primary secondary amine (PSA) solid-phase extraction cartridge. The detection of targets was performed by HPLC-MS/MS with multiple reaction monitoring (MRM) mode. All the seven pesticides were completely separated in 15 min with an excellent linear relationship. The limits of detection and the limits of quantification for the seven pesticides were 0.02-0.5 μg/kg and 0.08-1.5 μg/kg, respectively. The recoveries of the seven pesticides spiked in a bamboo shoot sample at the levels of 4, 8, 32 μg/kg were in the range from 76.0% to 102.6% (the RSD≤11.0%, n=3). The method was successfully applied to the real bamboo shoot samples. The method has high accuracy and sensitivity, and is simple and quick. It can meet the requirement of the simultaneous determination of the seven pesticides in bamboo shoots.

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Determination of caftaric acid, p-coutaric acid and fertaric acid in grape juice, peel and seeds by ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry ZHANG Lingyi, WANG Zhicong, ZHANG Weibing* 2013, 31 (2):  122-126.  DOI: 10.3724/SP.J.1123.2012.09047 Abstract ( 1656 )   [Full Text(HTML)] () PDF (745KB) ( 504 )   An ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry (UPLC-MS/MS) method was developed for the determination of hydroxycinnamoyltartaric esters, such as caftaric acid, p-coutaric acid and fertaric acid in grape juice, peel and seed. The target analytes were separated on a Waters UPLC HSS T3 column (150 mm×2.1 mm, 1.7 μm) at 35 ℃ with gradient elution at a flow rate of 0.3 mL/min. The grape juice was freeze-centrifuged, the supernatant was diluted with 20% methanol. The grape peel and grape seed samples were extracted with 80% ethanol. The extract was cleaned-up on-line with the analytical column by valve switching technology. The mobile phases were water-acetonitrile (both containing 0.1% formic acid). The identification and quantification were achieved by MS/MS in multiple reaction monitoring (MRM) mode via negative electrospray ionization. As lack of commercial standards, p-coutaric acid and fertaric acid were quantified by caftaric acid equivalent. The developed method showed a good linearity over the range of 25-2000 μg/L with good correlation coefficient (r2=0.9989). The limit of detection was 0.25 μg/L, and the limit of quantification was 25 μg/L. The average recoveries of caftaric acid were between 97.7%-99.5% and the precisions were within 2.5% at the spiked levels of 250, 750 and 1200 μg/L. The working solutions were stable for 74 h at room temperature. The results showed that there are significant differences of hydroxycinnamoyltartaric esters distribution in grape juice, peel and seeds. Therefore, this method, owing to its simplicity, rapidity, good recovery, high sensitivity and accuracy, can be used for the analysis of caftaric acid, p-coutaric acid and fertaric acid in grape juice, peel and seeds.

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Research on the application of grey system theory in the pattern recognition for chromatographic fingerprints of traditional Chinese medicine WEI Hang1, LIN Li2*, ZHANG Yuan1, WANG Lianjing2, CHEN Qinqun1 2013, 31 (2):  127-132.  DOI: 10.3724/SP.J.1123.2012.09017 Abstract ( 1550 )   [Full Text(HTML)] () PDF (1880KB) ( 534 )   A model based on grey system theory was proposed for pattern recognition in chromatographic fingerprints (CF) of traditional Chinese medicine (TCM). The grey relational grade among the data series of each testing CF and the ideal CF was obtained by entropy and norm respectively, then the principle of “maximal matching degree” was introduced to make judgments, so as to achieve the purpose of variety identification and quality evaluation. A satisfactory result in the high performance liquid chromatographic (HPLC) analysis of 56 batches of different varieties of Exocarpium Citrus Grandis was achieved with this model. The errors in the chromatographic fingerprint analysis caused by traditional similarity method or grey correlation method were overcome, as the samples of Citrus grandis ‘Tomentosa’ and Citrus grandis (L.) Osbeck were correctly distinguished in the experiment. Furthermore in the study on the variety identification of Citrus grandis ‘Tomentosa’, the recognition rates were up to 92.85%, although the types and the contents of the chemical compositions of the samples were very close. At the same time, the model had the merits of low computation complexity and easy operation by computer programming. The research indicated that the grey system theory has good applicability to pattern recognition in the chromatographic fingerprints of TCM.

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Simultaneous determination of five cold medicine ingredients in paracetamol triprolidine hydrochloride and pseudoephedrine hydrochloride tablets by pH/organic solvent double-gradient high performance liquid chromatography XUAN Xueyi, HUANG Lina, PAN Xiaoling, LI Ning* 2013, 31 (2):  133-138.  DOI: 10.3724/SP.J.1123.2012.09023 Abstract ( 1791 )   [Full Text(HTML)] () PDF (1437KB) ( 364 )   A pH/organic solvent double-gradient mode in reversed-phase high performance liquid chromatography (HPLC) has been established as a new approach to the simultaneous determination of acetaminophen, caffeine, salicylamide, pseudoephedrine hydrochloride and triprolidine hydrochloride in paracetamol triprolidine hydrochloride and pseudoephedrine hydrochloride tablets. Through the optimization of the organic solvent gradient mode and pH/organic solvent double-gradient mode, the optimum double-gradient HPLC system of the five cold medicine ingredients has been built. The determination was carried out on a Diamonsiol C18 column (250 mm×4.6 mm, 5 μm). The mobile phase consisted of methanol, 0.05 mol/L ammonium acetate solution and 0.08 mol/L acetic acid solution. The column temperature was set at 30 ℃. The flow rate was 1.0 mL/min. The sample was measured at multiple wavelengths: 0-6 min, 280 nm; 6-7 min, 257 nm; 7-14 min, 280 nm; 14 min, 233 nm. The separation of the five cold medicine ingredients in the tablets was achieved in 25.5 min. The linear ranges of acetaminophen, pseudoephedrine hydrochloride, caffeine, salicylamide and triprolidine hydrochloride were 0.055-0.998 g/L, 0.053-0.946 g/L, 0.007-0.129 g/L, 0.035-0.622 g/L and 0.002-0.039 g/L, respectively, with their correlation coefficients greater than 0.9990. The detection limits (S/N=3) were 0.09, 6, 0.02, 0.128 and 0.02 mg/L, respectively. Their mean recoveries were 97.9%-102.8%. The advantage of the method is the simultaneous determination of acidic, neutral and basic compounds. It also can improve the column efficiency of the analyte, compress the half-peak width and reduce the trailing. The optimized and validated method can be used for the simultaneous determination of the five cold medicine ingredients in the tablets.

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Simultaneous determination of benzotriazoles and benzothiazole in surface water by solid phase extraction and high performance liquid chromatography WANG Jincheng1, XIONG Li2, ZHANG Haijun1, WANG Longxing1, JIN Jing1, CHEN Jiping1* 2013, 31 (2):  139-142.  DOI: 10.3724/SP.J.1123.2012.09029 Abstract ( 1557 )   [Full Text(HTML)] () PDF (749KB) ( 440 )   A simple method based on solid phase extraction (SPE) coupled with high performance liquid chromatography (HPLC) was developed for the determination of 1H-benzotriazole (BT), 5-methyl-1H-benzotriazole (5-M-BT), 5,6-dimethyl-1H-benzotriazole (5,6-DM-BT), 5-chloro-1H-benzotriazole (5-Cl-BT) and benzothiazole (BTH) in surface water. The extraction and clean-up of the surface water sample were performed on an HLB solid-phase extraction cartridge. The separation of the five compounds was achieved on a ZORBAX SB-C18 column (250 mm×4.6 mm, 5 μm) with methanol-water (55:45, v/v) as mobile phase and ultraviolet detection. The quantification was achieved by external standard method. The results showed that good linearities were observed in the ranges of 0.064-80 mg/L with the correlation coefficients ≥ 0.9999 and the instrumental limits of detection for the five target compounds were in the range of 1.9-3.2 μg/L. The average recoveries of the five target compounds were 87.8%-125.6% and the relative standard deviations (n=3) were 0.4%-9.4%. This method was applied to the analysis of the surface water samples from the Dalian tap water and the Liaohe River estuary. The results showed that BT, 5-M-BT, 5-Cl-BT and BTH were found in the water from the Liaohe River estuary.

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Determination of the solubility parameter of organosolv lignin by inverse gas chromatography YU Yachen, LI Kunlan, MA Yingchong*, WEI Ligang 2013, 31 (2):  143-146.  DOI: 10.3724/SP.J.1123.2012.09024 Abstract ( 1650 )   [Full Text(HTML)] () PDF (741KB) ( 364 )   An inverse gas chromatographic (IGC) method has been used to measure the solubility parameters (δ2) of organosolv lignin at the absolute temperatures from 333.15 K to 373.15 K. The test probe solvents were n-octane (n-C8), n-decane (n-C10), n-dodecane (n-C12), and n-tetradecane (n-C14). The specific retention volumes of the solvents (V0g), the molar enthalpy of sorption (ΔHs1), the partial molar enthalpy of mixing at infinite dilution (ΔH∞1), the molar enthalpy of vaporization (ΔHv), the activity coefficients at infinite dilution (Ω∞1), and Flory-Huggins inter action parameters (χ∞12) between organosolv lignin and probe solvents were obtained. The results showed that the above four probes are poor solvents for organosolv lignin; at the same temperature, the χ∞12 reduced with the increase of the carbon number of probe solvents. The average solubility parameter of organosolv lignin was determined as 19.03 (J\5cm-3)1/2.

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Characterization of surface properties of 1-allyl-3-methylimidazolium chloride ionic liquid by inverse gas chromatography CHEN Yali, WANG Qiang*, DENG Lishuang, ZHANG Zhengfang, TANG Jun 2013, 31 (2):  147-150.  DOI: 10.3724/SP.J.1123.2012.10006 Abstract ( 1305 )   [Full Text(HTML)] () PDF (734KB) ( 276 )   The determination of the dispersive component of surface free energies (γds) at different temperatures and Lewis acid-base parameters of 1-allyl-3-methylimidazolium chloride ionic liquid (［AMIM］Cl) were investigated by means of inverse gas chromatography (IGC). Four n-alkanes, including n-hexane (C6), n-heptane (C7), n-octane (C8) and n-nonane (C9), were chosen as the apolar probes to characterize the dispersive component of the surface free energies at 343.15, 353.15, 363.15 and 373.15 K, respectively; and dichloromethane (DCM), trichloromethane (TCM), tetrahydrofuran (THF), ethyl acetate (EtAc), acetone (Acet) as the polar probes to estimate the Lewis acid-base parameters to judge the interactions between ［AMIM］Cl and the solvents. The IGC characterizations encompassed the adsorption thermodynamic parameters to acid-base surface interactions, including the standard enthalpy (ΔHsa) and the free energy change of adsorption (ΔGsa) at different temperatures. The results showed that the Lewis acid parameter Ka of ［AMIM］Cl was 0.34, and the base parameter Kb was 1.68, which indicated it was Lewis amphoteric with predominantly basic character. Furthermore, the free energy of adsorption ΔGsa was also figured out. It was found that the γds of the ［AMIM］Cl were 52.26, 50.82, 46.08 and 42.05 mJ/m2 at 343.15, 353.15, 363.15 and 373.15 K, respectively. The results are of great importance to the study of the surface properties and the application of ionic liquid.

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Isolation and purification of enhanced green fluorescent protein using chromatography HOU Qinghua1,2, SONG Shuliang1,2, LIANG Hao1,2, WANG Weili1,2, JI Aiguo1,3* 2013, 31 (2):  151-154.  DOI: 10.3724/SP.J.1123.2012.10004 Abstract ( 1706 )   [Full Text(HTML)] () PDF (1399KB) ( 480 )   Enhanced green fluorescent protein (EGFP) is a common biological marker. In this research, on the foundation of successful clone and expression of EGFP, a two-step chromatographic method was established to separate and purify EGFP, which includes the use of HisTrap HP immobilized metal affinity chromatography (IMAC) and Sephadex G-10 HR size exclusion chromatography in sequence. Sephacryl S-300 HR size exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to check out the purity of EGFP. At last, it was found that EGFP still had fluorescent activity using fluorescence spectrophotometric detection and Native-PAGE detection. This method can effectively separate the active EGFP. The purity of the obtained EGFP was more than 98%.

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Simultaneous determination of four phthalate esters in water samples using ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography MA Yanling1,2, CHEN Lingxin1,2*, DING Yangjun1, MING Yongfei3, LI Jinhua2 2013, 31 (2):  155-161.  DOI: 10.3724/SP.J.1123.2012.09003 Abstract ( 1557 )   [Full Text(HTML)] () PDF (795KB) ( 423 )   Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography(UA-DLLME-HPLC)was developed for the determination of four typical phthalate esters (PAEs). The analyzed PAEs included dimethyl phthalate(DMP), diethyl phthalate(DEP), dibutyl phthalate(DBP)and di-n-octyl phthalate(DnOP). The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents, ultrasonic time, ionic strength and extraction time, were investigated. Enrichment factor (EF)was employed to evaluate the extraction efficiency. The conditions were finally chosen: CCl4 (40 μL)/acetonitrile (1.0 mL) as extraction/dispersion solvents; 30 g/L NaCl; ultrasound/centrifugation of 5 min. Under the optimized extraction conditions, UA-DLLME exhibited strong enrichment ability for the four PAEs. The EFs for DMP, DEP, DBP and DnOP obtained were 71, 144, 169 and 159, respectively. The limits of detection were 3.78, 1.77, 3.07 and 3.30 μg/L for DMP, DEP, DBP and DnOP, respectively. The satisfactory recoveries for three water samples at three spiked levels ranged from 82.99%-114.47%, with the relative standard deviations of 1.93%-8.31%. It is a convenient, speedy, environmentally benign method for the routine analysis of PAEs in water samples.

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Determination of four fluorescent whitening agents in laundry detergents by solid phase extraction combined with ultra-high performance liquid chromatography XIAN Yanping, GUO Xindong, LUO Haiying, WU Yuluan*, CHEN Yiguang, LUO Donghui, WU Wenhai 2013, 31 (2):  162-169.  DOI: 10.3724/SP.J.1123.2012.09041 Abstract ( 1408 )   [Full Text(HTML)] () PDF (842KB) ( 521 )   A new method was established to determine three stilbene-type disulfonate and one distyrylbiphenyl-type fluorescent whitening agents (FWA351, FWA85, FWA28 and FWA71) in laundry detergents by solid phase extraction (SPE) and ultra-high performance liquid chromatography with a diode array detector (UPLC-DAD). The fluorescent whitening agents were extracted from laundry detergents with 2% formic acid aqueous solution and methanol, and purified by WAX SPE column, and analyzed by UPLC-DAD on a Phenomenex Synergi Max-RP column (150 mm×2.0 mm), employing acetonitrile-10 mmol/L ammonium acetate as the mobile phase in a gradient elution mode. The fluorescent whitening agents were qualitatively determined by retention time, and confirmed by the ultraviolet spectrum. The results indicated that the target analytes were in the range of 0.05-180 mg/L with the correlation coefficients (r) greater than 0.9993, and the method limits of quantification (MLOQ) of target analytes were ranged from 1.5 mg/kg to 15 mg/kg (S/N=10). The feasibility of this method was demonstrated by the determination of FWAs in samples with spiked recoveries. The recoveries were in the range between 84.9% and 105%, and the precision (relative standard deviation, RSD) ranged from 3.2% to 6.1% (n=6). Among the 15 samples analyzed, the rate of positive samples was 53.3%, over 1000 mg/kg of FWA351 and FWA71 were detected. The method is simple, precise and has high recoveries for the determination of fluorescent whitening agents in laundry detergent samples.

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Rapid determination of six preservative residues in fruits and vegetables by high performance liquid chromatography using dispersive solid phase extraction LIN Haidan*, ZOU Zhifei, QIN Yan, XIE Shouxin, CHEN Yufang, XU Juan, WANG Lan, CHEN Chuying 2013, 31 (2):  170-173.  DOI: 10.3724/SP.J.1123.2012.09035 Abstract ( 1636 )   [Full Text(HTML)] () PDF (727KB) ( 370 )   A dispersive solid phase extraction-high performance liquid chromatographic (HPLC) method was established for the simultaneous determination of 2,4-D, thiabendazole, 2-naphthol, o-phenyl phenol, diphenyl ether and biphenyl in the fruits and vegetables. The samples were vortexed for extraction with acetonitrile containing sodium chloride and anhydrous magnesium sulfate. The acetonitrile extraction was purified by acidic alumina dispersed solid phase extraction. The analysis was performed on an Agilent TC C18 column (250 mm×4.6 mm, 5 μm) and an ultraviolet detector at 235 nm with a mobile phase of methanol-0.02 mol/L (pH 6) potassium dihydrogen phosphate solution, at a flow rate of 1.0 mL/min with gradient elution. Good linearities were observed in the range of 0.5-20 mg/L with correlation coefficients greater than 0.99. The average recoveries of the six preservatives in fruits and vegetables were in the range of 84.2%-99.1% at three spiked levels of 1, 2 and 10 mg/kg (n=6) and the relative standard deviations (RSDs) were in the range of 1.67%-10.3%. The limits of quantification were 1 mg/kg. This method is simple, accurate and suitable for the determination of the six preservatives in fruits and vegetables.

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Simultaneous determination of 1-sulfo-cyclohexane carboxylic acid and sulfate anion in the by-products of caprolactam by high performance liquid chromatography-indirect photometric analysis YAN Zhixiang, DUAN Zhengkang*, LI Linan, LI Haitao, CHEN Qiuyun, PENG Ye 2013, 31 (2):  174-178.  DOI: 10.3724/SP.J.1123.2012.09020 Abstract ( 1250 )   [Full Text(HTML)] () PDF (740KB) ( 478 )   An improved anion-exchange chromatographic method was developed for simultaneous quantification of 1-sulfo-cyclohexane carboxylic acid (SCCA) and sulfate anion in the by-products of caprolactam. An strong anion chromatographic column and an ultraviolet (UV) detector were chosen for the assay of SCCA and sulfate anion. Non-chromophore-containing sulfate anion is not directly adaptable to the commonly used ultraviolet detection of high performance liquid chromatography (HPLC). This paper reports the development and validation of an HPLC assay for SCCA and sulfate anion based on indirect ultraviolet detection. An ultraviolet-absorbing reagent (the probe), phthalic acid (PA), was added to the mobile phase to induce a signal for the compound. The proposed method was qualified based on the performance criteria of repeatability, intermediate precision and linearity. The limits of detection were 1.0 g/L for both the analytes. The linear ranges varied from 0.50 to 40.0 g/L for SCCA and from 0.10 to 10.0 g/L for sulfate anion, with the correlation coefficients of 0.99997 and 0.99914, and the recoveries of 93.33%-97.40% and 98.50%-101.00%, respectively. The established method can be used in practice to determine SCCA and sulfate anion simultaneously with perfect separation selectivity.