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Chinese Journal of Chromatography
2014, Vol. 32, No. 1
Online: 08 January 2014

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2013 annual review of capillary electrophoresis technology ZHAO Xinying, QU Feng, WANG Yong, WANG Xiaoqian 2014, 32 (1):  1-6.  DOI: 10.3724/SP.J.1123.2013.12022 Abstract ( 1330 )   [Full Text(HTML)] () PDF (774KB) ( 338 )   This paper reviews the capillary electrophoresis (CE) in 2013. Six international and two national conferences are included and the important reports are introduced briefly. Literatures searched from ISI Web of Science ranged in 2013.1.1-2013.12.7 are classified and introduced based on the biology and medicine applications as well as the use of detectors and the important analytical chemical journals.

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Advances in isolation and enrichment of circulating tumor cells in microfluidic chips DU Jinghui, LIU Xu, XU Xiaoping 2014, 32 (1):  7-12.  DOI: 10.3724/SP.J.1123.2013.08009 Abstract ( 1402 )   [Full Text(HTML)] () PDF (2272KB) ( 504 )   The research of circulating tumor cells (CTCs) has drawn increasing attention in recent years, because its potential value in the early diagnosis of cancers, management of clinical treatment, development of personalized medicine, and exploring the mechanism of metastasis. However, the difficulty in using CTCs lies in their extremely low concentrations. Recently, microfluidic devices have shown the potential to efficiently isolate and detect rare CTCs in cancer patients. A variety of on-chip blood analysis has been demonstrated by several groups. The advantages of microfluidics include low cost, short reaction times, high throughput, and ease of use. Recently, a variety of microfluidic devices have been developed to CTCs isolation and enrichment which can realize high capture efficiency, high purity and high throughput. In this article, we review some of the recent works in microfluidic CTCs isolation and enrichment devices and discuss in what field should be done next based on our researches.

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Simultaneous determination of 20 illegally added anti-diabetic chemical components in hypoglycemic and weight-reducing health foods by ultra-high performance liquid chromatography-tandem mass spectrometry ZHU Feng, RUAN Liping, MA Yongjian, JI Wenliang, LIU Hualiang 2014, 32 (1):  13-20.  DOI: 10.3724/SP.J.1123.2013.08035 Abstract ( 952 )   [Full Text(HTML)] () PDF (1366KB) ( 523 )   A rapid method for the simultaneous screening and detection of 20 illegally added anti-diabetic chemical components in hypoglycemic and weight-reducing health foods was developed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After extracted by methanol, the sample was separated on a Poroshell 120 EC C18 column (100 mm×2.1 mm, 2.7 μm) with the gradient elution of 5 mmol/L ammonium acetate and acetonitrile as mobile phases. The electrospray ionization (ESI) source in positive or negative ion mode was used for multiple reaction monitoring (MRM) mode. The 20 illegally added chemical components showed good linear relationships with the correlation coefficients more than 0.99. The recoveries were in the range of 75.9%-114.0%, and the relative standard deviations (RSDs) were all not more than 11.3%. The limits of detection (LODs) were all in the range of 0.3-1.5 μg/L. This method is rapid, simple, sensitive, accurate and of good specificity for cracking down illegally added anti-diabetic chemical components.

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Determination of thiourea dioxide in lotus seed paste fillings by solid phase extraction-liquid chromatography-tandem mass spectrometry WANG Hui, ZENG Xiwen, CHANG Xiaotu, PENG Xinkai, XIA Lixin, LI Yiwei 2014, 32 (1):  21-25.  DOI: 10.3724/SP.J.1123.2013.07015 Abstract ( 1125 )   [Full Text(HTML)] () PDF (849KB) ( 384 )   A method of solid phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) was developed to determine thiourea dioxide which was illegally added into lotus seed paste fillings. An amount of 0.05% (v/v) acetic acid was used to extract thiourea dioxide from fillings, and the BOND ELUT PLEXA column (60 mg/3 mL) was used as the SPE column to clean-up the extraction. Then, an Agilent HILIC column (100 mm×2.1 mm, 3.5 μm) was applied to separate target compounds by using the mobile phases of 0.01 mol/L ammonium acetate (pH 3.5) and acetonitrile. Qualitative and quantitative analyses were operated by the multiple reaction monitoring (MRM) mode. The calibration curve showed a good linearity for the target compound in the detection range of 10-1000 μg/L. The limit of detection (LOD) and limit of quantitation (LOQ) of this method were 8.0 μg/kg and 30.0 μg/kg, respectively. The recoveries were in the ranges of 75.3%-80.7% with the RSDs of no more than 4.83%. This proposed method was rapid, highly specific and suitable for the confirmation and quantitative determination of thiourea dioxide in lotus seed paste fillings.

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High throughput analysis of cerebroside molecular species from sea cucumber Parastichopus californicus by liquid chromatography-quadrupole-time-of-flight mass spectrometry XING Peipei, XU Jie, CONG Peixu, WANG Yang, HE Zhongyang, XUE Changhu 2014, 32 (1):  26-33.  DOI: 10.3724/SP.J.1123.2013.08002 Abstract ( 890 )   [Full Text(HTML)] () PDF (1689KB) ( 372 )   Cerebrosides from sea cucumber Parastichopus californicus were identified by using liquid chromatography-quadrupole-time-of-flight mass spectrometry (LC-Q-TOF MS/MS). The samples were extracted with chloroform-methanol (2:1, v/v) solution and purified by a SPE cartridge. In positive ion mode electrospray ionization (ESI), the precursor ion scan mass spectra and product ion scan mass spectra were obtained through the automatic MS/MS mode. Cerebroside molecules were selected according to the neutral loss fragments of 180 Da, and then were identified according to long-chain base (LCB) fragments and fatty acid (FA) fragments. One hundred and twenty-three cerebroside molecular species were identified. There are 18 species of LCB, and the relative content ratio of phytosphingosines and sphingosines is 1:2. The carbon numbers of fatty acids are mainly 18-25, of which 24 carbon fatty acids are predominant. The relative content ratio of saturated fatty acids and monounsaturated fatty acid is about 1:3, and the presence of 2-hydroxy fatty acids is about 58.62%. LC-Q-TOF MS/MS method is sensitive, accurate and simple. At the same time, this study provided a theoretical basis for structure-activity relationship studies and functional food development of Parastichopus californicus as well.

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Determination of carcinogenic aromatic amines derived from azo colorants in plastic components of electrical and electronic products by high performance liquid chromatography-mass spectrometry NIU Zengyuan, LUO Xin, YE Xiwen, WANG Huihui, LI Jingying 2014, 32 (1):  34-39.  DOI: 10.3724/SP.J.1123.2013.08005 Abstract ( 1161 )   [Full Text(HTML)] () PDF (941KB) ( 357 )   A study for the simultaneous determination of 21 primary aromatic amines derived from the reduction of the azo colorants in plastic components of electrical and electronic products was conducted. Organic solvents were used to dissolve or swell the plastics to release the azo dyes existing in the plastic components. The azo colorants were reduced to aromatic amines under strong reducing condition of dithionite. Aromatic amines were extracted with methyl tert-butyl ether. Methanol-water (1:1, v/v) was used to concentrate the extract to constant-volume for HPLC-MS analysis. The analytes were separated on a ZORBAX Eclipse XDB C18 column using the gradient elution with acetonitrile and 0.1% (v/v) formic acid aqueous solution at a flow rate of 0.6 mL/min. The analyte confirmation was performed using retention time and characteristic ions in selected ion monitoring (SIM) mode. The correlation coefficients (r) of all the standard curves were more than 0.998, and the limits of quantification of the analytes were 0.5 mg/kg. The recoveries were 60.1%-129.5% for the 21 aromatic amines with the RSDs not more than 14.0% except for a few compounds. The results showed that the banned azo colorants in the plastic products can be analyzed qualitatively and quantitatively through reductive conversion into aromatic amines. In addition, this method has high accuracy and good precision.

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Determination of phenolic compounds in fresh tobacco leaves by high performance liquid chromatography-ultraviolet/mass spectrometry SHEN Danhong, LU Xin, CHANG Yuwei, ZHANG Junjie, ZHAO Yanni, WANG Ying, XU Guowang, ZHAO Chunxia 2014, 32 (1):  40-46.  DOI: 10.3724/SP.J.1123.2013.08004 Abstract ( 946 )   [Full Text(HTML)] () PDF (921KB) ( 378 )   Twenty-five phenolic compounds in tobacco were analyzed using high performance liquid chromatography-ultraviolet/mass spectrometry (HPLC-UV/MS), including absolute quantification of 11 main phenols by HPLC-UV and relative quantification of other 14 phenols by HPLC-MS. The validation results of this method were satisfactory. Eleven phenol standards showed good linearity with correlation coefficients (r2) of 0.9993-0.9999 over the mass concentration range from 0.90 mg/L to 99.00 mg/L (the range of chlorogenic acid and rutin was from 0.95 mg/L to 380.00 mg/L). The recoveries of the 11 phenol standards were 91.0%-112.4% with the RSDs of 0.33%-8.11% at the three spiked levels of 22.5-24.8, 45.0-49.5 and 67.5-74.3 mg/L. The reproducibility of the method was good with the RSDs of 1.48%-13.40%. In addition, the intra-day and inter-day precisions were also satisfactory with the RSDs of 0.35%-15.54%. Mature fresh tobacco leaves from Yunnan, Henan and Guizhou Provinces, China were analyzed using this method. The results showed that the total amount of main phenols was Guizhou>Yunnan>Henan and there was significant difference between Guizhou and Henan. The amount of rutin was Yunnan>Guizhou>Henan, and there were significant differences among them each other. The method is reproducible with a simple pretreatment covering a wide range of phenols, and can be applied in batch analysis of tobacco leaves.

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Determination of triterpenoic acid isomers in Eriobotryae folium using high performance liquid chromatography on C30 column ZHANG Yong, XUE Kunpeng, ZHOU An, YU Huimin, LI Yin, YAO Lixin, ZHAO Yuexing, XIE Xiaomei 2014, 32 (1):  47-51.  DOI: 10.3724/SP.J.1123.2013.08019 Abstract ( 965 )   [Full Text(HTML)] () PDF (986KB) ( 401 )   A rapid and easy assay method for four triterpenoic acid isomers in Eriobotryae folium was established. The sample was extracted with methanol, then separated on a C30 column (250 mm×4.6 mm, 5 μm) at 20 ℃ using acetonitrile-water (95:5, v/v) as the mobile phase at a flow rate of 1.0 mL/min. The target compounds were simultaneously detected at 210 nm, and the injection volume was 10 μ L. The validation was carried out and the resolution (R≥2.2), the precision (RSD≤1.1%), the linearity (r≥0.9992), the repeatability (RSD≤4.4%), and the recovery (range from 95.4% to 101.7%, RSD≤4.8%) were acceptable. The method is reliable for the quantification of the four triterpenoic acid isomers by HPLC on C30 column.

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Determination of seven additives in polymer products by ultra performance supercritical fluid chromatography ZHANG Yun, DU Zhenxia, YU Wenlian 2014, 32 (1):  52-56.  DOI: 10.3724/SP.J.1123.2013.08036 Abstract ( 662 )   [Full Text(HTML)] () PDF (932KB) ( 133 )   A method for rapid determination of seven commonly used additives in polymer products by ultra performance supercritical fluid chromatography (UPSFC)-photodiode array detector (PDA) was developed. In this experiment, the detection wavelength was set at 220 nm. After the important parameters of UPSFC, such as the diluting solvent, mobile phase additive, column temperature, automatic back pressure regulator (ABPR) and flow rate were investigated, the optimized conditions were acquired as follows: n-hexane/isopropanol (1/1, v/v) was chosen as the diluting solvent, the mixture of methanol/acetonitrile (1/1, v/v) as the mobile phase additive, 2 mL/min as the flow rate, 50 ℃ as the column temperature, 12.41-13.79 MPa as the ABPR. Under these conditions, seven additives were separated in 5 min, and full baseline separation was achieved. The real sample was pretreated by microwave-assisted extraction (MAE) and analyzed by UPSFC-PDA. The seven additives can be detected with the recoveries of 69.9%-118.9%, and the relative standard deviations (RSDs, n=9) were less than 10%. This method is simple, fast with good selectivity and suitable for the analysis of the additives in polymer products.

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Rapid screening and quantitative analysis of 144 pesticide residues in traditional Chinese medicinal herbs by gas chromatography-tandem mass spectrometry CHENG Zhi, ZHANG Rong, LIU Weihua, WANG Jinhua, WANG Minglin 2014, 32 (1):  57-68.  DOI: 10.3724/SP.J.1123.2013.09043 Abstract ( 1101 )   [Full Text(HTML)] () PDF (1606KB) ( 460 )   An analytical method for the simultaneous determination of 144 pesticide residues in traditional Chinese medicinal herbs was established based on optimized QuEChERS with gas chromatography-tandem mass spectrometry (GC-MS/MS). The influences of different extraction solvents, different buffer systems and different purifying agents on the recoveries of the pesticides were investigated. The pesticide residues in the samples were extracted with acetonitrile, then cleaned-up by mixed sorbents and analyzed by GC-MS/MS in multi-reaction monitoring (MRM) mode. The external standard method was applied to quantify the pesticides. The linear range of the method was from 20 to 2000 μg/kg with the correlation coefficients (r2) of more than 0.983. The recoveries of the pesticides at the spiked levels of 20, 50 and 200 μg/kg ranged from 74.3% to 111.8% with the relative standard deviations lower than 15%, except for acephate, amitraz and aldrin. The method was successfully used for the analysis of target pesticides in testing samples, and had a good consistency in results with the existed standard one. This multi-residue analytical method allows for a rapid, efficient, sensitive and reliable screening and quantitative analysis of the target pesticides in traditional Chinese medicinal herbs.

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Simultaneous determination of nine preservatives in fruits using gas chromatography-mass spectrometry PENG Shunü, WANG Qiuquan, FANG Lanlan, GUO Shanyong, ZENG Zhouhua, LIN Zhuguang 2014, 32 (1):  69-73.  DOI: 10.3724/SP.J.1123.2013.06035 Abstract ( 1008 )   [Full Text(HTML)] () PDF (812KB) ( 333 )   A gas chromatography-mass spectrometry (GC-MS) method was established for the simultaneous determination of nine typical preservatives (pyrimethanil, chlorothalonil, chlorpyrifos, triadimefon, thiabendazole, imazalil, myclobutanil, iprodione, prochloraz) in fruits. The fruit samples were subjected to ultrasonic extraction with hexane/ethyl acetate (1/1, v/v), and followed by purification using diatomite column chromatography with hexane/ethyl acetate (1/3, v/v) eluant. Qualitative and quantitative analysis of the nine preservatives were performed on the GC-MS at full-scan (SCAN) and selected ion monitoring (SIM) modes, in which triphenylphosphate was used as the internal standard. The detection limits obtained for the nine preservatives were ranged from 0.10 μg/kg to 2.16 μg/kg. The average recoveries were in the range of 75.3% to 128% at the spiked levels of 50, 100 and 200 μg/kg with the relative standard deviations (RSDs) of 1.57% to 11.6% (n=5). The results showed that the developed method is sensitive and accurate for the determination of the nine preservatives in fruits.

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Determination of 39 polychlorinated biphenyls in indoor dust using ultrasonic extraction and gas chromatography-tandem mass spectrometry WANG Bingling, ZHANG Xiaoling, ZHANG Qi, LU Xiaomei, CUI Yuan, ZHANG Zhengdong 2014, 32 (1):  74-80.  DOI: 10.3724/SP.J.1123.2013.09007 Abstract ( 733 )   [Full Text(HTML)] () PDF (869KB) ( 153 )   A method for the determination of 39 polychlorinated biphenyls (PCBs) in indoor dust was developed. A vacuum cleaner was used for gathering the house dust. N-Hexane-dichloromethane (1:1, v/v) was added and the extraction was performed in an ultrasonic bath. The supernatant was concentrated and then 0.1 mL n-hexane-dichloromethane (1:1, v/v) was added. Gas chromatography-tandem mass spectrometry (GC-MS/MS) in selected-reaction monitoring (SRM) mode has been investigated for the determination of the 39 PCBs congeners in indoor dust. The 39 PCBs had highly efficient separation within 30 min and showed good linearity in the range of 0.1-100 μg/L with the correlation coefficients of 0.9910-0.9999. The spiked recoveries were 57.2%-120.3%. The intra-day relative standard deviations (RSDs) were between 0.3% and 24.7%, while the inter-day RSDs were between 0.6% and 29.9%. This method has good linearity, high sensitivity, high accuracy and precision. Also, it is simple, rapid and low solvent consumption. The low chemical background interference allowed it to be used in more complex matrices.

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Determination of migration of 15 N-nitrosamines and N-nitrosatable substances from children’s latex articles by gas chromatography-tandem mass spectrometry using solid phase extraction LI Pi, BAI Hua, LI Haiyu, CHEN Ming, LÜ Qing, ZHANG Qing 2014, 32 (1):  81-88.  DOI: 10.3724/SP.J.1123.2013.08032 Abstract ( 1258 )   [Full Text(HTML)] () PDF (941KB) ( 405 )   A method based on gas chromatography-tandem mass spectrometry (GC-MS/MS) using solid phase extraction (SPE) has been developed for the determination of 15 N-nitrosamines from children's latex articles. Artificial saliva was used as the migration solution to extract N-nitrosamines in children's latex articles. And then a polar modified polystyrene-divinylbenzene copolymer (Chromabond Easy) was used for the selective SPE of the analytes in the migration solution. The analytes were then separated on an HP-5MS UI GC column and determined by MS/MS in multiple reaction monitoring mode for qualitative and quantitative analysis. Good linearity ranged from 5 μg/L to 2000 μg/L was observed for all the compounds (R2 >0.998) and the limits of quantification for the 15 N-nitrosamines were 0.625-12.50 μg/kg (S/N=10), which were lower than the limits required by the EU 2009/48/EC Directive. The average recoveries of the target analytes at low, medium, and high spiked levels were in the ranges of 53.8%-116.2%, 52.7%-105.1% and 49.5%-102.9%, respectively. The average within-day and between-day RSDs were from 1.3% to 14.0% (n=6) and from 1.6% to 7.6% (n=4), respectively. The proposed method was used to monitor N-nitrosamines in baby nipples and balloons, and N-nitrosamines were found in some samples. The total contents of the 15 N-nitrosamines in the analyzed nipples and balloons samples ranged from 0.0499 mg/kg to 41.2 mg/kg. And the total contents of the N-nitrosatable substances in the analyzed samples ranged from 0.0264 mg/kg to 12.5 mg/kg.

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Determination of N-nitrosamines in rubber products by solid phase extraction purification and ultra high performance liquid chromatography-tandem mass spectrometry CHEN Ting, WEN Yuyun, OU Yan, GONG Zhenbin 2014, 32 (1):  89-94.  DOI: 10.3724/SP.J.1123.2013.08003 Abstract ( 1113 )   [Full Text(HTML)] () PDF (1020KB) ( 403 )   A method using C18 solid phase extraction (SPE) for purification and ultra high performance liquid chromatography (UHPLC) coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS) for detection was developed to simultaneously determine 13 N-nitrosamines in rubber products. The analytes were extracted with methanol (60 ℃, 30 min) with the aid of ultrasonic technique and then purified by a C18 SPE cartridge. The analytes were separated on a C18 chromatographic column and qualitatively and quantitatively detected by a mass spectrometer with positive ESI at multiple reaction monitoring (MRM) mode. The operating parameters for UHPLC separation and ESI-MS/MS detection were also optimized. Under optimum operating conditions, the relative standard deviations (RSDs, n=7) were less than 10% at spiked level of 50 μg/kg for all analytes except N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) which were spiked at 500 μg/kg. The recoveries spiked in real samples were from 70.7% to 117.0%. The limits of detection (LODs, 10 times of standard deviation) were in the range of 0.5-500 μg/kg. The method has been successfully applied to the simultaneous determination of the 13 N-nitrosamines in rubber products.

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Analysis of the preservative chlorphenesin in cosmetics by high performance liquid chromatography ZHU Huijuan, ZHANG Weiqiang, YANG Yanwei, ZHU Ying 2014, 32 (1):  95-99.  DOI: 10.3724/SP.J.1123.2013.07036 Abstract ( 1888 )   [Full Text(HTML)] () PDF (809KB) ( 480 )   An analytical method was developed for the determination of the preservative of chlorphenesin in cosmetics by high performance liquid chromatography (HPLC). A C18 column (250 mm×4.6 mm, 5 μm) and a photodiode array detector were used. The mobile phase was methanol-water (55:45, v/v) with a flow rate of 1.0 mL/min. The detection wavelength was set at 280 nm and the column temperature was 25 ℃. The limit of detection was 3 ng. A good linear relationship was obtained between the peak area and the mass concentration of chlorphenesin in the range of 1-500 mg/L and the correlation coefficient was 1.0000. The recoveries of chlorphenesin at different spiked levels were 99.0%-103% with the relative standard deviations (RSD) ≤1.2%. Interference test and sample test were also applied meanwhile and validation experiments were performed by three laboratories. The method is simple, sensitive, accurate, stable and suitable for the determination of chlorphenesin in cosmetics.

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Process analysis for levulinic acid generated in waste wood liquefaction by non-development thin-layer chromatography based on oblique projection SU Hui, GE Jun, FANG Feng, YAO Zhixiang, SONG Guangjun 2014, 32 (1):  100-104.  DOI: 10.3724/SP.J.1123.2013.08008 Abstract ( 771 )   [Full Text(HTML)] () PDF (1572KB) ( 311 )   A rapid and quantitative method is presented for multi-component process analysis, based on multi-wavelength thin-layer chromatography (TLC) scanning but without the routine development. The samples from the waste wood liquefaction process are applied on silica plates, and just the last sample of spot need to be developed for getting separated spectra. These spectra are divided into two parts of production (levulinic acid) and background, respectively, to build an oblique projection operator. The other process samples do not need to be developed repeatedly, and are scanned to collect hybrid spectra immediately. The pure production spectrum can be separated from the process spectrum by the oblique projection algorithms to realize the production quantification. It was showed that the relative errors between the determination results by this method and those by high performance liquid chromatography (HPLC) were less than 3.27%, and so the consistency is perfect.