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Chinese Journal of Chromatography
2013, Vol. 31, No. 12
Online: 28 December 2013

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Simultaneous dual protein labeling WANG Hailin 2013, 31 (12):  1141-1142.  DOI: 10.3724/SP.J.1123.2013.10033 Abstract ( 510 )   [Full Text(HTML)] () PDF (776KB) ( 88 )

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Inductively coupled plasma mass spectrometry based bioanalysis WANG Qiuquan 2013, 31 (12):  1143-1145.  DOI: 10.3724/SP.J.1123.2013.11035 Abstract ( 550 )   [Full Text(HTML)] () PDF (1696KB) ( 92 )

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Recent advances in preparation of novel chromatographic stationary phases with carbon nanotubes HE Shiwei, HUANG Zhongping, ZHU Yan 2013, 31 (12):  1146-1153.  DOI: 10.3724/SP.J.1123.2013.08043 Abstract ( 925 )   [Full Text(HTML)] () PDF (6877KB) ( 221 )   Carbon nanotubes (CNTs) as a new functional material have attracted the interest of scientists and engineers in analytical chemistry, due to their excellent physical, chemical and mechanical properties. The preparation of gas chromatographic stationary phases with CNTs has been performed by packing method or in situ catalytic chemical vapor deposition. The deposition of CNTs on a chromatographic solid matrix (e. g. silica micro-particles or organic polymer microspheres) was carried out to generate a packing material for high performance liquid chromatography. Capillary monolithic columns for liquid chromatography were also prepared by embedding CNTs in polymer monolithic columns. Columns with CNTs have the unique advantages in the separation of aromatic compounds for the π electron system of CNTs. Herein, the recent applications of CNTs in the preparation of chromatographic stationary phases are reviewed, including gas chromatography and liquid chromatography. The future developments in this field are also prospected.

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Application of liquid chromatography-mass spectrometry in the research of Alzheimer’s disease TIAN Shijun, PENG Xianglei, ZHENG Yanpeng, HE Jinsheng, HONG Tao 2013, 31 (12):  1154-1160.  DOI: 10.3724/SP.J.1123.2013.07014 Abstract ( 1052 )   [Full Text(HTML)] () PDF (882KB) ( 210 )   Liquid chromatography-mass spectrometry (LC-MS) combining with both highly efficient separation and detection is widely applied to chemistry, medicine, pharmacy biochemistry etc. Particularly, the application of LC-MS to clinic chemistry opened a new chapter for diagnosis technologies. Alzheimer's disease (AD), also called as senile dementia, is the fourth leading cause of death in modern society. With the rapid aging of population, the prevention and treatment of AD need to be strengthened. In this review, we briefly introduce the new LC-MS developments and discuss the applications of LC-MS techniques in AD research in the last three years.

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Simultaneous determination of clopidol, sulfonamide and quinolone residues in chickens by ultra performance liquid chromatography-tandem mass spectrometry SONG Wei, HU Yanyun, HAN Fang, LV Yaning, ZHENG Ping, ZHOU Fangfang, CHEN Xiaomei, QIU Jing, ZHOU Xiaoying 2013, 31 (12):  1161-1166.  DOI: 10.3724/SP.J.1123.2013.08022 Abstract ( 1333 )   [Full Text(HTML)] () PDF (1527KB) ( 315 )   An analytical method for the simultaneous determination of clopidol, sulfadiazine, sulfamethazine, sulfametoxydiazine, sulfamethoxypyridazine, norfloxacin, ofloxacin, ciprofloxacin, enrofloxacin in chickens by ultra performance liquid chromatography coupled with tandem quadrupole mass spectrometry (UPLC-MS/MS) in positive ion mode with multiple reaction monitoring (MRM) has been developed and validated. The samples were homogenized and extracted with acetonitrile. After defatted with high speed frozen centrifugation, the supernatant solution was evaporated and the residue was dissolved with the mobile phase and defatted with n-hexane. It was then analyzed with UPLC-MS/MS. The limit of detection of this method was 0.1 μg/kg, and the limit of quantification was 0.5 μg/kg. The average recoveries (spiked at the levels of 0.5, 1.0, 2.0 μg/kg) ranged from 81.5% to 97.6%, with the relative standard deviations between 2.1% and 8.9%. The results demonstrated that the method is simple, accurate and suitable for the identification and quantification of these drug residues in chickens.

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Determination of 51 carbamate pesticide residues in vegetables by liquid chromatography-tandem mass spectrometry based on optimization of QuEChERS sample preparation method WANG Lianzhu, ZHOU Yu, HUANG Xiaoyan, WANG Ruilong, LIN Zixu, CHEN Yong, WANG Dengfei, LIN Dejuan, XU Dunming 2013, 31 (12):  1167-1175.  DOI: 10.3724/SP.J.1123.2013.05051 Abstract ( 1345 )   [Full Text(HTML)] () PDF (1248KB) ( 347 )   The raw extracts of six vegetables (tomato, green bean, shallot, broccoli, ginger and carrot) were analyzed using gas chromatography-mass spectrometry (GC-MS) in full scan mode combined with NIST library search to confirm main matrix compounds. The effects of cleanup and adsorption mechanisms of primary secondary amine (PSA), octadecylsilane (C18) and PSA+C18 on co-extractives were studied by the weight of evaporation residue for extracts before and after cleanup. The suitability of the two versions of QuEChERS method for sample preparation was evaluated for the extraction of 51 carbamate pesticides in the six vegetables. One of the QuEChERS methods was the original un-buffered method published in 2003, and the other was AOAC Official Method 2007.01 using acetate buffer. As a result, the best effects were obtained from using the combination of C18 and PSA for extract cleanup in vegetables. The acetate-buffered version was suitable for the determination of all pesticides except dioxacarb. Un-buffered QuEChERS method gave satisfactory results for determining dioxacarb. Based on these results, the suitable QuEChERS sample preparation method and liquid chromatography-positive electrospray ionization-tandem mass spectrometry under the optimized conditions were applied to determine the 51 carbamate pesticide residues in six vegetables. The analytes were quantified by matrix-matched standard solution. The recoveries at three levels of 10, 20 and 100 μg/kg spiked in six vegetables ranged from 58.4% to 126% with the relative standard deviations of 3.3%-26%. The limits of quantification (LOQ, S/N≥10) were 0.2-10 μg/kg except that the LOQs of cartap and thiofanox were 50 μg/kg. The method is highly efficient, sensitive and suitable for monitoring the 51 carbamate pesticide residues in vegetables.

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Simultaneous determination of six estrogens in different water bodies by solid phase extraction and ultra performance liquid chromatography coupled with triple quadrupole mass spectrometry ZENG Yuzhu, ZHANG Yong, DONG Liangfei, ZHANG Beibei, ZHAO Yonggang 2013, 31 (12):  1176-1181.  DOI: 10.3724/SP.J.1123.2013.08011 Abstract ( 904 )   [Full Text(HTML)] () PDF (882KB) ( 234 )   A method has been developed for the simultaneous determination of six estrogens (estriol, 17-β-estradiol, 17-α-estradiol, estrone, ethinyloestradiol, diethylstilbestrol) in water environment by solid phase extraction and ultra performance liquid chromatography couple with triple quadrupole mass spectrometry. After enriched and purified by an HLB solid phase extraction column, the six estrogens were separated by a BEH C18 column and then determined by MS/MS with multiple reaction monitoring (MRM) mode. The quantification was achieved by internal standard method, with estriol-D3, estradiol-D2 and diethylstilbestrol-D8 as the internal standards. Good linear relationships were obtained in the mass concentration range of 1.0-100 μg/L with high correlation coefficients over 0.9982. The limits of detection and quantification for the six estrogens were 0.27-0.45 ng/L and 1.08-1.78 ng/L, respectively. The recoveries were in the range of 68.3%-97.4% at the three spiked levels and with the relative standard deviations below 15%. The method shows high sensitivity, good precision, extensive analytical range and high analytical speed. It was successfully applied to the simultaneous detection of the six estrogens in four different water bodies including surface water, waste water, source water of drinking and domestic water.

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Determination of twenty free amino acids in flue-cured tobacco leaves using ultra performance liquid chromatography-single quadruple mass spectrometry and pre-column derivatization LI Haoli, ZHAO Chunxia, ZHANG Junjie, FU Jiajun, WANG Ying, LU Xin, XU Guowang 2013, 31 (12):  1182-1188.  DOI: 10.3724/SP.J.1123.2013.08006 Abstract ( 970 )   [Full Text(HTML)] () PDF (907KB) ( 393 )   Free amino acids in flue-cured tobacco leaves were investigated using the ultra performance liquid chromatography-single quadruple mass spectrometry detection and pre-column derivatization method. The validation results showed that the method could meet the analytical requirements. A total of 138 tobacco leaf samples were collected from 14 provinces in China in 2011 in which the free amino acids were determined. The relative standard deviations (RSDs) of the contents of free amino acids in different growing regions ranged from 28.50%-94.20%, and those of asparagine and glutamine were over 80%. The RSDs of the contents of free amino acids in full aroma tobacco leaves were larger than those in fresh aroma and medium aroma tobacco leaves. The principal component analysis (PCA) and non-parameter Mann-Whitney U test were used for data analysis. The free amino acids of the same aroma type grown in different regions or different aroma types in the same province showed great variation. The contents of free amino acids of full aroma tobacco grown in Southeast region were much lower than those in Huanghuai region. The contents of free amino acids in Hunan province were much lower than the average contents. The results showed that free amino acids in flue-cured tobacco leaves were affected by the growing region.

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Simultaneous determination of five Amadori compounds in tobacco by high performance liquid chromatography-mass spectrometry WANG Hongrui, XIE Yuanyuan, LIANG Qionglin, WANG Yiming, HU Ping, LUO Guoan 2013, 31 (12):  1189-1193.  DOI: 10.3724/SP.J.1123.2013.06029 Abstract ( 792 )   [Full Text(HTML)] () PDF (876KB) ( 211 )   A method of high performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-QqQ MS) in multiple reaction monitoring (MRM) mode for simultaneous determination of five Amadori compounds in tobacco has been developed. The separation was performed on an XBridgeTM Amide column (250 mm×4.6 mm, 3.5 μm) by gradient elution using methanol and water as mobile phases. The linearity of this method was good with the correlation coefficients (r) of 0.9895-0.9989. The limits of detection (S/N=3) were from 3.51 μg/L to 14.86 μg/L, and the limits of quantitation (S/N=10) were from 10.18 μg/L to 44.58 μg/L. The recoveries varied from 92.6% to 123.6% with the relative standard deviations (RSDs) less than 9.4%. The established method is rapid, accurate, robust and convenient, and it could be applied to the measurement of the five Amadori compounds in tobacco and cigarettes.

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International comparison APMP.QM-P23：determination of benzoic acid in orange juice GUO Zhen, FU Hui, LI Xiuqin, ZHANG Qinghe 2013, 31 (12):  1194-1200.  DOI: 10.3724/SP.J.1123.2013.09003 Abstract ( 1044 )   [Full Text(HTML)] () PDF (904KB) ( 372 )   A method was developed for the separation and determination of benzoic acid in orange juice by high performance liquid chromatography-ultraviolet detection (HPLC-UV) and liquid chromatography-isotope dilution mass spectrometry (LC-IDMS). National Institute of Metrology (NIM) of China participated the international comparison activity organized by Asia Pacific Metrology Programme (APMP) and got good results using this method. The effects of several important factors, such as the chromatographic conditions and sample preparation conditions, were investigated to acquire optimum conditions. A method of uncertainty determination was also developed which can be used in similar measurements of uncertainty. The limit of detection (LOD, S/N>3) of HPLC-UV method was 0.75 mg/kg, and the recovery of benzoic acid in orange juice at the spiked level 100 mg/kg was 99.4%. The LOD of LC-IDMS method was 0.05 mg/kg, and the recovery of benzoic acid at the same spiked level was 99.6%. The final determination result of benzoic acid in the orange juice sample by both methods was (102.0±2.1) mg/kg (coverage factor k=2). The two methods are both simple, accurate, reliable and reproducible. The LC-IDMS method is more suitable for the determination of benzoic acid at low concentrations due to its high sensitivity.

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Simultaneous determination of δ13C values of glycerol and ethanol in wine by liquid chromatography coupled with isotope ratio mass spectrometry LI Xuemin, JIA Guangqun, CAO Yanzhong, ZHANG Jinjie, WANG Lei, SUN Huiyuan 2013, 31 (12):  1201-1205.  DOI: 10.3724/SP.J.1123.2013.07027 Abstract ( 966 )   [Full Text(HTML)] () PDF (1147KB) ( 275 )   A novel procedure was established for the characterization of δ13C values of glycerol and ethanol in wine by liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). Several parameters influencing the separation of glycerol and ethanol from wine matrix were optimized. The precision and accuracy of the proposed method were 0.15‰ to 0.26‰ and 0.11‰ to 0.28‰, respectively. The results obtained for 40 wine samples displayed that the δ13C value of glycerol ranged from -26.87‰ to -32.96‰ and that of ethanol ranged from -24.06‰ to -28.29‰. Close correlations (R=0.82) were obtained between the δ13C values of glycerol and ethanol. The proposed method didn't need complex sample treatment, and the δ13C values of glycerol and ethanol in wine can be simultaneously determined, thus improving the method in terms of simplicity and speed compared with traditional methods.

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Effect of alcoholic strength on the determination of ethyl carbamate in Chinese spirits by high performance liquid chromatography-fluorescence detection CHEN Dawei, MIAO Hong, ZHAO Yunfeng, WU Yongning 2013, 31 (12):  1206-1210.  DOI: 10.3724/SP.J.1123.2013.07023 Abstract ( 1027 )   [Full Text(HTML)] () PDF (865KB) ( 239 )   A high performance liquid chromatography-fluorescence detection (HPLC-FLD) method was established for rapid determination of ethyl carbamate (EC) in Chinese spirits. Through the analysis and comparison of the EC peak areas in different alcoholic strengths determined by HPLC-FLD, the effect of alcoholic strength on the determination of the content of EC was found. The alcoholic strength and the peak area of EC showed good linearity in the range of 5% to 65% (v/v) alcohol content, and the correlation coefficients (R2) were higher than 0.98. Furthermore, the conversion between the peak area of EC with different alcoholic strengths was established by the relative correction coefficient. The method showed a good linearity in the range of 10 to 500 μg/L for EC with the average recoveries of 98.9%-108.2% and RSDs of 0.6%-4.9%. The reliability of the established HPLC-FLD method was evaluated by comparison with GC-MS method. The results showed that the results of two methods were not significantly different. The developed method is simple, sensitive, accurate, and suitable for the rapid determination of EC in Chinese spirits.

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Determination of 34 pesticide residues in rice, proso millet and wheat with QuEChERS-on line gel permeation chromatography-gas chromatography-mass spectrometry RUAN Hua, RONG Weiguang, MA Yongjian, JI Wenliang, LIU Hualiang, SONG Ninghui 2013, 31 (12):  1211-1217.  DOI: 10.3724/SP.J.1123.2013.07029 Abstract ( 1070 )   [Full Text(HTML)] () PDF (910KB) ( 413 )   A method for the simultaneous determination of 34 pesticides in rice, proso millet and wheat by QuEChERS coupled with on line gel permeation chromatography-gas chromatography-mass spectrometry (GPC-GC-MS) was developed. The effects of the sample weight, extraction solvent, sorbent for purification were investigated. The matrix effect and the usefulness of analyte protectant were also studied. The identification and quantification were performed by GPC-GC-MS in selected ion monitoring (SIM) mode and external standard method. The calibration curves of the 34 pesticides showed good linearity in the range of 0.0125-0.2 mg/L with the correlation coefficients (r2) between 0.968 and 0.999. The average recoveries were 94.5%-117.1%, 83.1%-121.7% and 93.1%-120.2% with the relative standard deviations (RSDs, n=6) no more than 14.5%, 15.1% and 15.2% in rice, proso millet and wheat samples, respectively. The LODs of this method were 0.0281-5.31, 0.0282-4.82 and 0.0273-5.13 μg/kg (S/N=3) for rice, proso millet and wheat samples, respectively. The low cost and less consumption of reagents of this method are in accordance with the concept of green chemistry. The convenient operation and versatility of this method are suitable for the fast screening and detection of the 34 pesticide residues in rice, proso millet and wheat.

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Determination of benzene series in marine sediment by headspace solid phase microextraction-gas chromatography-mass spectrometry WU Jinhao, WANG Zhaohui, WANG Bai, ZHOU Zunchun, WANG Nianbin 2013, 31 (12):  1218-1223.  DOI: 10.3724/SP.J.1123.2013.07025 Abstract ( 1033 )   [Full Text(HTML)] () PDF (882KB) ( 368 )   A method was developed for the determination of benzene series (BTEX) in marine sediment by headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The conditions for extraction and gas chromatography, such as the amount of salt added, equilibrium time, extraction temperature, extraction time, desorption time and injection temperature, were optimized. The analytes were quantitatively analyzed by the internal standard method. The results showed that the linear correlation coefficients of BTEX compounds were from 0.995 to 0.999 in the range of 0.500-20.0 ng/g. The detection limits of this method were from 0.0818 to 0.175 ng/g, with the RSDs of inter- and intra-day of 1.2%-3.6% (n=5) and 0.4%-6.3% (n=3). The average recoveries under two different spiked concentrations (2.0 and 15.0 ng) were 61.7%-79.5% and 77.1%-85.6% with RSDs of 5.4%-9.6% and 3.9%-7.6% (n=5), respectively. This method is quick, sensitive, simple, accurate and reproducible. It can be used to analyze the marine sediment samples with trace BTEX.

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Determination of the total amount of maleic acid and maleic anhydride in starch and its products by high performance liquid chromatography-tandem mass spectrometry XU Dunming, CHEN Yan, ZHOU Shuang, LIAN Yingjie, CHEN Luping, LIN Liyi, ZHOU Yu, HUANG Zhiqiang 2013, 31 (12):  1224-1227.  DOI: 10.3724/SP.J.1123.2013.07011 Abstract ( 1259 )   [Full Text(HTML)] () PDF (830KB) ( 469 )   A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established for the determination of the total amount of maleic acid and maleic anhydride in starch and its products. The samples were extracted with 50% (v/v) methanol and hydrolyzed by alkaline, then analyzed by HPLC-MS/MS, and quantified with the external standard method. The mass spectrometry was operated with electrospray in negative ionization mode. The multiple reaction monitoring (MRM) mode was employed involving the transition of the precursor ion to two selected product ions, in which one pair was for quantification (m/z 115.0>71.1) and the other pair was for identification (m/z 115.0>27.1). The results indicated that no significant matrix effect was found for the spiked samples. The recoveries of maleic acid spiked in starch and its products were 80.2%-115.3% at spiked levels of 0.5-1000 mg/kg. The relative standard deviations (RSDs) were less than 12% (n=6). The limits of detection (LOD) and quantification (LOQ) were 0.1 and 0.5 mg/kg for maleic acid and maleic anhydride, respectively. The method is rapid, sensitive and reproducible for the determination of the total amount of maleic acid and maleic anhydride in starch and its products and shows great potential for routine analysis

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Determination of lutein in infant formula milk powder using ultra-high performance liquid chromatography WANG Lina, HUANG Junrong, ZHANG Li, FENG Feng, LING Yun, CHU Xiaogang, LI Hongliang 2013, 31 (12):  1228-1231.  DOI: 10.3724/SP.J.1123.2013.10007 Abstract ( 916 )   [Full Text(HTML)] () PDF (833KB) ( 221 )   An ultra-high performance liquid chromatography (U-HPLC) method for the determination of lutein in the infant formula milk powder was developed. The sample was extracted with acetone and defatted using freezing centrifugation method. The U-HPLC separation was achieved using a YMC Carotenoid C30 column (150 mm×4.6 mm, 3 μm) with the mixture of methanol/methyl tert-butyl ether (70:30, v/v) as the mobile phase under isocratic elution. The flow rate was 0.5 mL/min and the column oven temperature was 25 ℃. The injection volume was 5 μL. It was detected on a photodiode array detector at a wavelength of 445 nm. The results showed that the linear range was 20-500 μg/L (r=0.999 9), and the limit of quantification was 20 μg/L. The mean recoveries of lutein varied from 97.9% to 104.4% spiked at 50, 250 and 2000 μg/kg. The established method is simple, accurate and sensitive for the rapid determination of lutein in infant formula milk powder.

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Determination of ten photoinitiators in fruit juices and tea beverages by solid-phase micro-extraction coupled with gas chromatography/mass spectrometry LIU Pengyan, CHEN Yanjie, ZHAO Chunxia, TIAN Lei 2013, 31 (12):  1232-1239.  DOI: 10.3724/SP.J.1123.2013.07019 Abstract ( 849 )   [Full Text(HTML)] () PDF (923KB) ( 280 )   A method for the determination of ten photoinitiators (PIs), benzophenone, ethyl 4-dimethylaminobenzoate, 1-hydroxycyclohexyl-phenylketone, 4-methylbenzophenone, 2-ethylhexyl-4-dimethylaminobenzoate, 4-chlorobenzophenone, 2-chlorothioxanthone, 2-isopropylthioxanthone, 2,2-dimethoxy-2-phenylacetophenone, methyl 2-benzoylbenzoate, in 13 kinds of fruit juice and 3 kinds of tea beverage has been established, using solid-phase micro-extraction (SPME) combined with chromatography/mass spectrometry (GC/MS). At first, the major factors of SPME, extraction time and temperature, were studied through orthogonal experiment. Then the optimal operation conditions were obtained via the refinement of various factors. After the sample was extracted by SPME, it was desorbed for target analytes in sampling inlet for 3 min, and separated on an HP-5MS column, then detected by MS in selected ion monitoring mode, and quantified through calibration curve. The working curves were obtained using sample matrix in order to eliminate the matrix interference. The linear range was from 0.3 μg/L to 60 μg/L and the detection limit range was from 3 ng/L to 16 ng/L. The samples were determined five times with four different spiked levels individually and the relative standard deviations of all the samples were less than 14.5%. This determination method was applied in 16 kinds of packed beverages with different brands and different species. Benzophenone had been detected from all the samples. 4-Methylbenzophenone, 2-ethylhexyl-4-dimethylaminobenzoate, 2-isopropylthioxanthone, 1-hydroxycyclohexyl-phenylketone and 2-chlorothioxanthone had been detected from a portion of samples. Simultaneous determination was achieved for the ten PIs. These results provide a reference to determine the PIs migrated from packing materials in beverage. This method is simple, high sensitive and non-polluting.