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Chinese Journal of Chromatography
2017, Vol. 35, No. 3
Online: 08 March 2017

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Important progress in ion chromatography and its recent developments in China ZHAO Xinying, QU Feng, MOU Shifen 2017, 35 (3):  223-228.  DOI: 10.3724/SP.J.1123.2016.12029 Abstract ( 631 )   [Full Text(HTML)] () PDF (856KB) ( 243 )   This review provides some important progress in ion chromatography (IC), which includes Reagent-Free IC system, novel valve switching part, weakly ionized organic acid analysis, novel IC columns for fast analysis, IC coupled with pre-treatment technology, inductively coupled plasma mass spectrometry (ICP-MS) and IC coupled with hydride generation-atomic fluorescence spectrometry (HG-AFS), as well as IC applications in bioanalysis and pharmaceutical analysis. The review also introduces briefly the recent developments of IC in China, such as research of IC hardware technology, modification of instrument regulation, development of standard methods and revision of Chinese Pharmacopoeia.

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Progress in strategies for enrichment of proteome terminal peptides CHEN Lingfan, SHAN Yichu, ZHANG Lihua, ZHANG Yukui 2017, 35 (3):  229-236.  DOI: 10.3724/SP.J.1123.2016.10040 Abstract ( 455 )   [Full Text(HTML)] () PDF (988KB) ( 114 )   Termini of proteins are not only the origin and destination of protein synthesis, but also participating in and mediating a host of physiological functions of proteins. The determination of proteins termini provides valuable information for protein structure and function annotation, and helps the profiling of proteases substrates and cleavage sites. Herein, the progress in the strategies for enrichment of protein terminus is reviewed. In the meantime, the applications of terminome analysis for the identification of protease substrate and cleavage site are briefly introduced. Finally, the future of terminome research is discussed.

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Progress in the applications of functionalized metal-organic frameworks for adsorption and removal of pollutants in drinking water FENG Dan, WEI Cuixiang, XIA Yan 2017, 35 (3):  237-244.  DOI: 10.3724/SP.J.1123.2016.10013 Abstract ( 608 )   [Full Text(HTML)] () PDF (1308KB) ( 220 )   Metal-organic frameworks (MOFs) are a class of periodical porous crystalline materials. They are built from organic heterocyclic compounds as ligands and transition metal ions as center via coordination interaction. Compared with other porous materials, MOFs possess a great variety of ligands, extraordinary surface areas, tunable pore sizes and special metal sites (saturated or unsaturated), which makes them many potential applications in analytical chemistry. Recent years, functionalized MOFs have drawn a growing interest in enrichment and removal of pollutants. The functionalized MOFs can promote the adsorption capacities through changing MOFs' physicochemical properties (such as pore sizes and electric charges on the surface, etc.). This review summarizes the progress in the applications of functionalized MOFs in adsorption removal of pollutants in drinking water in recent years, including the classification and harm of pollutants in drinking water, the synthesis and applications of functionalized MOFs in removal of pollutants in water, and gives the prospects in the end.

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Research progress of separation methods for nanoparticles MIAO Lin, JI Jingwei, WANG Hefang 2017, 35 (3):  245-251.  DOI: 10.3724/SP.J.1123.2016.10008 Abstract ( 750 )   [Full Text(HTML)] () PDF (1153KB) ( 316 )   The separation of nanoparticles has been one of the fundamental but difficult hotspots in the rapid-developed fields of nanotechnologies. In this review, the main methodologies for separation of the nanoparticles, including field flow fraction, ultracentrifugation, membrane separation, chromatography and magnetic separation method, are briefly introduced. The advantages and disadvantages, the specific application examples and research progresses of each method are evaluated. These separation methods are also discussed in respects of the separation effect of the samples, reusability and specificity.

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Specific recognition and detection of target proteins by new fluorescence molecularly imprinted membrane ZHANG Xin, JIANG Rui, YANG Shu, SUN Liquan, PANG Siping, LUO Aiqin 2017, 35 (3):  252-254.  DOI: 10.3724/SP.J.1123.2016.10001 Abstract ( 552 )   [Full Text(HTML)] () PDF (828KB) ( 258 )   A new method for producing L-cysteine-capped ZnS quantum dots (QDs) embedded molecularly imprinted membrane (QDs@MIM) was developed. The QDs@MIM was used as fluorescence artificial receptor for specific recognition and detection of target proteins. The QD@MIM was fabricated on a silylanized glass plate. Lysozyme, acrylamide, L-cysteine modified Mn2+-doped ZnS QDs and N,N'-methylenediacrylamide were used as template, functional monomer, assistant monomer and cross-linker, respectively. Under optimal conditions, the linear range for lysozyme ranged from 0.1 to 1.0 μmol/L, adsorption time was 4 min and the imprinting factor for lysozyme was 6.2. The results showed that the molecularly imprinted polymer can be used as a simple, rapid and selective biosensor to detect target proteins in biologic samples.

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Synthesis of functional mesoporous silica and selective adsorption of surface-exposed histidine proteins WANG Jiaojiao, YANG Xiaxia, LIU Xiaoyan, ZHANG Haixia 2017, 35 (3):  255-259.  DOI: 10.3724/SP.J.1123.2016.10021 Abstract ( 447 )   [Full Text(HTML)] () PDF (900KB) ( 81 )   The Cu2+immobilized mesoporous silica particles (PPOSS-IDA-Cu2+) were fabricated. The prepared materials were applied to the highly specific separation of surface-exposed histidine proteins, based on immobilized metal ion affinity chromatography. The adsorption experiments of bovine serum albumin, myoglobin, lysozyme and bovine hemoglobin (BHb) exhibited that PPOSS-IDA-Cu2+ had excellent performance in the separation of protein BHb. The maximum binding capacity of the proposed materials for BHb was 3150 mg/g. The results also demonstrated that PPOSS-IDA-Cu2+ had potential application in removing highly abundant proteins in proteomic analysis, and can be combined with other techniques to get more information on low abundant proteins.

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Preparation and application of a novel immobilization enzyme reactor based on DNA strand displacement reactions SONG Jiayi, SU Ping, YANG Ye, YANG Yi 2017, 35 (3):  260-263.  DOI: 10.3724/SP.J.1123.2016.10023 Abstract ( 507 )   [Full Text(HTML)] () PDF (836KB) ( 105 )   A novel enzyme immobilization method was developed. The enzyme was immobilized using single-stranded DNA modified magnetic nanoparticles as carriers through DNA strand displacement reactions. Alkaline phosphatase (ALP) was immobilized with partly complementary capture DNA-functionalized nanoparticles (MNPs@capDNA) by highly specific Watson-Crick hybridization to obtain the MNPs@DNA-ALP. For trypsin immobilization, the MNPs@DNA-Trypsin was obtained by the incubation of MNPs@DNA-ALP with trypsin-target DNA conjugates to trigger a toehold-mediated DNA strand displacement reactions. The enzymes can be replaced without damage by the immobilized enzyme procedure. Therefore, the strategy gave the possibility to recycle the enzymes and save the production cost. The immobilized trypsin exhibited excellent reusability and improved digestion performance. The enzymatic activity remained more than 86% after 10 cycles. And the sequence coverage of myoglobin (Myo) was 95%±0% (n=3), which was higher than that obtained by the free enzyme for 12 h. The strategy provides a promising alternative platform for the enzyme immobilization and can be used in a large variety of enzymatic reactions.

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Capillary ion chromatography-mass spectrometry for determination of low relative molecular mass organic acids in culture media of Clostridium thermocellum ZHAO Haijie, LIANG Wenhui, LI Zhen, SHI Qinghao, JIAN Fangfang, FA Yun, LIU Huizhou 2017, 35 (3):  264-268.  DOI: 10.3724/SP.J.1123.2016.10010 Abstract ( 527 )   [Full Text(HTML)] () PDF (855KB) ( 97 )   A capillary ion chromatography-mass spectrometry method was proposed to determine low relative molecular mass organic acids in culture media of Clostridium thermocellum. The conditions of analysis were optimized and eight organic acids were detected simultaneously. The target compounds were separated on an IonSwift MAX-100 capillary column with potassium hydroxide solution as mobile phase by gradient elution, and detected under selected ion monitoring (SIM) mode. The mass spectrometry conditions were: spray voltage 3.0 kV, sheath gas 2000 kPa, capillary temperature 275℃. The relative standard deviations ranged from 1.45% to 5.99%. The coefficients of determination ranged from 0.9696 to 0.9986 and the mean recoveries were 89.0%-110.0%. The limits of detection of the eight organic acids were 0.01-0.50mg/L. This method was used to detect low relative molecular mass organic acids in culture media of Clostridium thermocellum with high sensitivity and good reproducibility.

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Fast detection of kanamycin in milk by protamine-aptamer-gold nanotechnology JIA Xiangyang, YOU Huiyan, FU Xiuli 2017, 35 (3):  269-273.  DOI: 10.3724/SP.J.1123.2016.10007 Abstract ( 820 )   [Full Text(HTML)] () PDF (875KB) ( 96 )   A bio-nanodetection system was developed for kanamycin based on electrostatic interaction between polycationic protamine and negatively charged aptamer or gold nanoparticles (AuNPs). The concentrations of protamine, aptamer and cations in the buffer solution were optimized. The results showed that there was a good linear correlation (R2=0.9928) between gold nanoparticles and kanamycin in the range of 5-5000 nmol/L with 20 mmol/L Na+, 1 mmol/L Mg2+, 2 mg/L protamine and 100 nmol/L aptamer. The limit of detection was 0.53 nmol/L. Under this experimental condition, the content of kanamycin in milk was detected, the recoveries were 96%-98%, and the relative standard deviations (RSDs) were 1.5%-3.2%. This method has the advantages of high selectivity, good sensitivity and wide linear range, and is useful in the detection of kanamycin in foods.

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Rapid screening and identification of α -glucosidase binding compounds in Chinese medicines by online affinity solid-phase extraction-high performance liquid chromatography-diode array detector-quadrupole time-of-flight mass spectrometry ZHANG Yuping, SHI Shuyun, CHEN Lin, CHEN Xiaoqing, ZHANG Shuihan 2017, 35 (3):  274-279.  DOI: 10.3724/SP.J.1123.2016.09027 Abstract ( 480 )   [Full Text(HTML)] () PDF (903KB) ( 139 )   Screening and analysis of bioactive compounds from natural products is a challen-ging work due to their complexity. This paper reports the hyphenation of affinity solid-phase extraction column (ASEC) using immobilized α-glucosidase and high performance liquid chromatography-diode array detector-quadrupole time-of-flight mass spectrometry (HPLC-DAD-Q-TOF-MS) for screening and identification of α-glucosidase binding compounds from Chinese medicines. Affinity solid-phase extraction (ASE) system was hyphenated with HPLC system via a four-port switching valve and a six-port injection valve as an interface for transferring effluents from ASE column to HPLC. Positive control ((+)-catechin) and negative control (salicylic acid) were performed with the approach to verify its specificity and reproducibility. Subsequently, the developed system was applied to the screening and identification of α-glucosidase inhibitors from Polygonatum odoratum. Five phenethyl cinnamides (N-cis-feruloyloctopamine, N-trans-p-coumaroyloctopamine, N-trans-feruloyloctopamine, N-trans-p-coumaroyltyramine and N-trans-feruloyltyramine) and four homoisoflavanones ((3R)-5,7-dihydroxyl-3- (2',4'-dihydroxylbenzyl)-chroman-4-one, (3R)-5,7-dihydroxyl-6-methyl-3-(4'-hydroxylbenzyl) -chroman-4-one, (3R)-5,7-dihydroxyl-6-methyl-8-methoxyl-3-(4'-hydroxylbenzyl)-chroman-4-one and (3R)-5,7-dihydroxyl-6,8-dimethyl-3-(4'-hydroxylbenzyl)-chroman-4-one) with α-glucosidase inhibitory activities were identified. The results were in accordance with those of ultrafiltration screening. With the online system developed, here we present a feasible, selective and effective strategy for the rapid screening and identification of enzyme inhibitors from complex mixtures.

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Improved human plasma identification coverage based on random oligonucleotide library immobilized magnetic particles DENG Nan, LIANG Zhen, BIAN Yangyang, ZHANG Mingjian, ZHANG Ke, ZHANG Lihua, ZHANG Yukui 2017, 35 (3):  280-285.  DOI: 10.3724/SP.J.1123.2016.10012 Abstract ( 528 )   [Full Text(HTML)] () PDF (900KB) ( 75 )   A novel human plasma proteome sample pretreatment strategy was developed based on the interaction of random oligonucleotides with human plasma proteins, such as ionic interaction, affinity interaction, hydrophobic interaction, hydrogen bonding or spatial structure and so on. Random oligonucleotide library was immobilized on the magnetic particles by biotin-avidin interaction, and dispersed in 20 mmol/L Tris-HCl buffer (pH 7.4), followed by incubation with plasma proteins. Two elution systems were used to elute the proteins interacted with random oligonucleotides, separately. Nano-RPLC-ESI-MS/MS analysis was performed for protein identification. The number of proteins identified after treatment was increased by 29.5%, and two elution systems displayed good complementarity (26.7%). The total ratio of spectral counts of the top ten high abundant protein in human plasma was decreased from 31.82% to 21.31% (elution system 1) and 26.20% (elution system 2). In all the proteins identified, the lowest abundant protein (0.29 ng/mL) was only identified after magnetic nanoparticles@single-stranded DNA (MNP@ssDNA) treatment, which demonstrated that this strategy not only decreased the abundance of highly abundant proteins, but also provided a new idea for digging more lowly abundant proteins.

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Enantioseparation of milnacipran enantiomers and the separation mechanism on β-cyclodextrin-based chiral stationary phases by high performance liquid chromatography ZHENG Zhen, CHEN Xiujuan, ZHAO Liang, LI Wuhong, HONG Zhanying, CHAI Yifeng 2017, 35 (3):  286-290.  DOI: 10.3724/SP.J.1123.2016.09048 Abstract ( 570 )   [Full Text(HTML)] () PDF (877KB) ( 154 )   A high performance liquid chromatography method was established for the enantiomeric separation of milnacipran enantiomers on β-cyclodextrin-based chiral stationary phases (CSPs). Chiral columns of Astec CYCLOBONDTM I 2000 series, such as the native β-cyclodextrin (Cyclobond I 2000), acetyl-β-cyclodextrin (AC-β-CD), 2,3-dimethyl-β-cyclodextrin (DM-β-CD) and 3,5-dimethylphenyl carbamate β-cyclodextrin (DMP-β-CD), were examined under the reversed-phase mode. The effects of cyclodextrin stationary phase, mobile phase composition, pH, flow rate and column temperature on the separation of milnacipran enantiomers were investigated. The inclusion process between AC-β-CD and milnacipran enantiomers was investigated and chiral recognition mechanism was studied with molecular docking technique and binding energy calculations. The optimized conditions were as follows: the chiral stationary phase was a column of Astec CYCLOBONDTM I 2000 AC (25 cm×4.6 mm, 5 μm), the mobile phase was acetonitrile-0.1% (v/v) pH 5.0 triethylamine acetate (TEAA) (5:95, v/v) with a flow rate of 0.4 mL/min and the detection wavelength was 220 nm. The injection volume was 10 μL and the column temperature was 25℃. The value of resolution (Rs) was 1.74 and the theoretical plates were 10125. The results suggested that hydrogen bonding ability played an important role in the chiral recognition process of milnacipran enantiomers. The developed method was rapid, effective and reproducible.

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Preparation of a novel magnetic molecularly imprinted polymer and its application for the determination of fluoroquinolone antibiotics TONG Yukui, HU Yue, XIA Qinfei, HUANG Wei, TIAN Miaomiao 2017, 35 (3):  291-301.  DOI: 10.3724/SP.J.1123.2016.09023 Abstract ( 778 )   [Full Text(HTML)] () PDF (3581KB) ( 141 )   This paper deals with a method based on magnetic molecularly imprinted polymers (MMIPs) as a sorbent. The method was used for simultaneous determination of fluoroquinolone antibiotics (ciprofloxacin, lomefloxacin, enoxacin, and norfloxacin) combined with high performance liquid chromatography (HPLC). MMIPs were characterized by different techniques (scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, Fourier transform infrared spectrometry and vibrating sample magnetometry). Several parameters affecting the adsorption/desorption, including the amount of MMIPs, extraction and desorption times, desorption solvent, and sample pH, were investigated and optimized. Under the optimum conditions, the limits of detection (LODs) and the limits of quantification (LOQs) of the method were calculated to be 4.1-21.3 μg/L and 13.7-71.0 μg/L, respectively, and the recoveries of spiked samples ranged from 70.6% to 103.6%. The prepared MMIPs could be employed to selectively preconcentrate and determine fluoroquinolone antibiotics from environmental water samples.

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Separation and purification of flavonoids from Mikania micrantha by macroporous resin combined with high speed countercurrent chromatography GENG Shan, WANG Juanqiang, XI Xingjun, CHU Qiao, DONG Genlai, MA Xiaomeng, ZHANG Huiwen, WEI Yun 2017, 35 (3):  302-307.  DOI: 10.3724/SP.J.1123.2016.10022 Abstract ( 547 )   [Full Text(HTML)] () PDF (913KB) ( 164 )   The present study established a method for the separation and purification of four flavonoids quercetin-3-O-rutinoside, kaempferol-3-O-rutinoside, luteoloside and astragalin from Mikania micrantha by using macroporous resin combined with high speed countercurrent chromatography (HSCCC). Macroporous resin was AB-8 and the eluent was 50% (v/v) ethanol. A two-phase solvent system composed of n-butanol/acetic acid/water (4:1:5, v/v) was used in HSCCC. Quercetin-3-O-rutinoside, kaempferol-3-O-rutinoside, luteoloside and astragalin with the purity of 90.12%, 98.55%, 98.33% and 99.23%, respectively, were successfully separated from Mikania micrantha by HSCCC using the lower phase of this solvent system as mobile phase in one run. This study pave a simple and efficient method that could be used in the following separation of flavonoids from invasive plants.

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Determination of isopropyl-β-D-thiogalactopyranoside in recombinant human growth hormone using reversed-phase high performance liquid chromatography and pulsed electrochemical detection WANG Li, LIN Birong 2017, 35 (3):  308-313.  DOI: 10.3724/SP.J.1123.2016.10037 Abstract ( 564 )   [Full Text(HTML)] () PDF (873KB) ( 98 )   A novel method for the determination of isopropyl-β-D-thiogalactopyranoside (IPTG), a sulfur-containing compound, a pharmaceutical additive in commercial recombinant human growth hormone (rhGH), has been developed using pulsed electrochemical detection (PED), following liquid chromatographic separation. A Dionex-500 ion chromatograph coupled with an electrochemical detector was employed, equipped with a gold working electrode and an Acclaim 300 analytical C18 column, with a mobile phase consisting of sodium acetate (NaOAc) buffer (pH 5.45, 0.01 mol/L) and acetonitrile (ACN) (90:10, v/v). The C18 phase has very high surface coverage, resulting in high capacity. Electrochemical characterization via cyclic voltammetry is the basis of optimization of the integrated pulsed amperometric detection (IPAD) waveform. PED at a gold electrode has proven to be selective for sulfur-containing compounds under mildly acidic conditions. Upon optimization, IPTG was found to have a limit of detection of 1 μg/L (0.1 pmol) with 25 uL injection volume. This method was successfully applied to the determination of IPTG in rhGH samples with the characteristics of simplicity, high sensitivity and good repeatability. The assay is also useful, efficient and low-cost in monitoring disulfide formation kinetics and assuring quality control for biopharmaceuticals.

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Determination of trace chlorine in caprolactam by ion chromatography coupled with multiple pyrolysis and enrichment pretreatment NI Lijun, LIU Jianyun, CHEN Zhu, TANG Bingjing, WANG Fang, LUAN Shaorong 2017, 35 (3):  314-317.  DOI: 10.3724/SP.J.1123.2016.10002 Abstract ( 431 )   [Full Text(HTML)] () PDF (829KB) ( 80 )   A method was developed for determination of trace chlorine in caprolactam samples by ion chromatography (IC) coupled with multiple pyrolysis and enrichment pretreatment. The caprolactam samples were treated by multiple pyrolysis at 800℃. Trace organic chlorine in samples was decomposed into chlorine or hydrogen chloride. The gas products of pyrolysis were absorbed and enriched in 5 mL 10 mmol/L NaOH solution, which was analyzed by IC with suppressed conductor. Under the optimum conditions, the linear relationship of Cl- was good in the range of 0.05-1.0 mg/L with correlation coefficient of 0.9997. The method detection limit of chlorine in caprolatam samples was 0.37 μg/g. For 0.8 mg/L Cl- standard solution, the RSDs of retention time, peak area and peak height were 0.04%, 0.24%, and 0.20%, respectively (n=7). The RSD of the contents of chlorine in caprolactam samples was 1.52% (n=4). The conversion ratio of Cl- standard solution ranged from 93.3% to 104.0%, and the spiked recoveries of the samples ranged from 95.3% to 113.1%. The method was applied to determine the contents of chlorine in caprolactam samples with simple operation, controlled pretreatment, low blank, low detection limit, good reproducibility and satisfactory results.

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Preparation of microporous organic polymer-based solid phase microextraction fiber and application to the determination of organochlorine pesticides GUO Huihua, CHEN Gang, MA Jiutong, JIA Qiong 2017, 35 (3):  318-324.  DOI: 10.3724/SP.J.1123.2016.10030 Abstract ( 474 )   [Full Text(HTML)] () PDF (946KB) ( 85 )   In the present work, a microporous organic polymer (MOP) was prepared with 1,3,6,8-tetrakis(p-formylphenyl)pyrene and melamine as monomers. The MOP material was adhered on a stainless steel fiber for headspace solid phase microextraction (HS-SPME). By combining with gas chromatography-electron capture detection, an online method was developed for the determination of organochlorine pesticides (OCPs) in rice samples. Four experimental parameters affecting the preconcentration efficiency were investigated in details. Under the optimum experimental conditions, extraction temperature of 80℃, extraction time of 25 min, NaCl mass concentration of 200 g/L, and desorption time of 6 min, high enrichment factors of 115-318 were achieved. The MOP-based fiber exhibited good linearity for OCPs in the range of 0.05-50 μg/kg. The detection limits ranged from 2.4 ng/kg to 11.3 ng/kg with relative standard deviations of 1.3%-13.1% for the same fiber and 2.3%-13.6% for different fibers. The developed method was proved to be simple and rapid and to be applied to the determination of trace amount of OCPs in rice samples.

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Determination of cinnamic acid and its derivatives by dispersive solid phase microextraction of graphene quantum dots magnetic composite nanoparticles coupled with capillary electrophoresis SUN Yaming, WU Qi, GAO Jie, ZHANG Xia, ZHAO Liang, DONG Shuqing 2017, 35 (3):  325-331.  DOI: 10.3724/SP.J.1123.2016.10017 Abstract ( 543 )   [Full Text(HTML)] () PDF (1186KB) ( 146 )   Composites of graphene quantum dots (GQDs) and Fe3O4(Fe3O4-GQDs) nanoparticles were prepared via a one-step co-precipitation approach. And the synthesized Fe3O4-GQDs nanoparticles were applied to the extraction of five compounds of cinnamic acid and its derivatives (cinnamic acid, 3,4-dimethoxycinnamic acid, 4-methoxycinnamic acid, ferulic acid and trans-4-hydroxycinnamic acid). Cinnamic acid and its derivatives were detected by capillary electrophoresis (CE). The pH of adsorption solution, adsorption time, amount of adsorbent and desorption time were investigated. The rapid and efficient preconcentration of the five cinnamic acid and its derivatives was successfully obtained with the satisfactory recoveries of 86.2%-96.2%, and relative standard deviations of 1.8%-4.3%. The results indicated that Fe3O4-GQDs magnetic nanoparticles were good pretreatment alternatives.

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Dissociation constant calculation of protein-single-stranded deoxyribonucleic acid interaction by kinetic capillary electrophoresis and its reliability analysis WEI Qiang, YANG Ge, GUAN Hua, QU Feng 2017, 35 (3):  332-338.  DOI: 10.3724/SP.J.1123.2016.10025 Abstract ( 375 )   [Full Text(HTML)] () PDF (930KB) ( 113 )   Nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) is used for the determination of the complex's dissociation constant Kd. In this paper, single-stranded deoxyribonucleic acid-binding protein (SSB) and single-stranded deoxyribonucleic acid (ssDNA) were taken as the interaction model. The electrophoretogram features of different interaction strengths were analyzed and the complex's Kd in different conditions were determined. Moreover, the error analysis method was established based on peak's integral deviation. The results indicated that the Kd calculation were influenced by the electrophoretogram differences of varied SSB-ssDNA interactions, SSB-ssDNA concentration ratio and capillary temperature. Besides, the results based on the SSB-5'-GGTTGGTGTGGTTGG-3' (15mer) aptamer of human thrombin interaction under 20℃ showed that the deviation generated when manually integrate the peak area had an effect on Kd calculation under previous experiment conditions. But the maximum relative deviation of Kd value in 10% of the deviation interval was less than 7% and the Kd value's error could be ignored. This paper confirms that the calculation method of kinetic parameters by NECEEM is reliable.

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Investigation on interactions between bovine thrombin, aptamer and active components in Danshen by capillary zone electrophoresis LI Yujuan, WU Guangxia, OU Wanlu, SUN Xinxin, QU Feng 2017, 35 (3):  339-343.  DOI: 10.3724/SP.J.1123.2016.10018 Abstract ( 400 )   [Full Text(HTML)] () PDF (886KB) ( 97 )   Investigation on interactions between bovine thrombin (B-Thr), aptamer29 (Apt29) and three active components (salvianic acid A sodium (SAS), protocatechuic acid (PA), ferulic acid (FA)) in Danshen was carried out by capillary zone electrophoresis (CZE). CZE conditions were as follows: capillary length of 40 cm, voltage of 15 kV, injection volume of 3.45 kPa, injection time of 5 s. By changing concentration of B-Thr or Apt29 with fixed levels of the three active components, binding constants (Kb) were calculated by Scatchard and non-specific binding equations to show interactions between B-Thr, Apt29 and the three active components. The results showed that PA had the strongest affinity to B-Thr with Kb 3.39×104L/mol. Kb between FA and B-Thr was 1.05×104 L/mol. SAS had no binding with B-Thr. FA showed stronger affinity with Apt29 than PA with Kb of 1.48×104 L/mol and 1.32×104 L/mol, respectively. The present study reported that interactions between the active constituents in Danshen and B-Thr/Apt29. New methods might be supplied for calculation of interactions between Apt (protein) and herbal drug molecules. And it could give insight for target discovery and delivery of herbal drug molecules.

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Analysis of biogenic amines in foods by capillary electrochromatography coupled with laser induced fluorescence detection ZHANG Bingyu, CAI Xiaorong, YIN Yanyan, LI Xinuo, LÜ Haixia, WU Xiaoping 2017, 35 (3):  344-350.  DOI: 10.3724/SP.J.1123.2016.10031 Abstract ( 445 )   [Full Text(HTML)] () PDF (912KB) ( 124 )   A rapid and sensitive method was established for the analysis of biogenic amines (tryptamine, histamine, tyramine, spermidine and spermine) in foods by capillary electrochromatography (CEC) coupled with laser induced fluorescence (LIF) detection, using 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) as the derivatization reagent. The biogenic amines were derivatized by NBD-F with 50 mmol/L borate buffer solution (pH 8.0) at 75℃ for 25 min. The obtained derivatives of biogenic amines were separated on a packed C18 capillary column with a mobile phase consisting of acetonitrile-ammonium acetate (20 mmol/L, pH 8.0) (75:25, v/v) and the flow rate of 0.03 mL/min. A supplementary pressure of 6.9 MPa and a separation voltage of -8 kV were applied. The limits of detection (LODs, S/N=3) were 0.1-1.0 μg/L, with spiked recoveries of 78.3%-113.9%. The method could be applied to detect biogenic amines in processed and fermented foods. Statistical comparison of the results with those of the reference HPLC method showed good agreement. It reveals some advantages on the sensitivity and analysis speed, which are significant to trace residue analysis of biogenic amines in foods.

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A picoliter microfluidic chip driven by negative pressure for quantifying nucleic acid accurately with isothermal amplification WU Wenshuai, DING Xiong, MU Ying 2017, 35 (3):  351-356.  DOI: 10.3724/SP.J.1123.2016.10005 Abstract ( 425 )   [Full Text(HTML)] () PDF (1057KB) ( 74 )   More accurate, sensitive, and convenient methods are eagerly expected for quantifying nucleic acid in precision medicine. Therefore, in this study, a high-density picoliter-level microfluidic chip is developed for the precise detection of nucleic acid, which is combined with a dual fluorescence system based on isothermal multiple self-matching-initiated amplification (IMSA). Multilayer soft lithography technique is applied to the fabrication of the mold of chip. Then, the chip is produced by molding with the material of polydimethylsiloxane (PDMS). In addition, a simple nano-waterproof layer lying up on the microcell array is able to efficiently prevent the water from evaporation during the IMSA. On the chip, a total of 120000 reactors with picoliter volume for each are integrated and the density reaches up to 7000 reactors per cm2. This device allows three samples counted through partitioning each into 40000 reactors at the same time. The sample can be sucked into each microcell of the chip by negative pressure equally without external power. Then, thermo-coagulation oil fills the channels to separate microcells automatically, avoiding the need of any valve. The microcells which contain the target are distinguished by a dual fluorescence system based on IMSA. Then, the accurate concentration of target can be calculated by the formula of Poisson distribution. As a proof-of-concept assay, the IMSA-based quantitative detection of hepatitis B virus (HBV) artificial plasmid DNAs by using this chip device was conducted. As indicated by the results, this device achieves a dynamic range of 106 and the upper limit of quantitation reaches 1.13×106 copies nucleic acid in 36 μL sample. Accordingly, this portable device with accurate quantitation ability and fast sample processing is very beneficial for precision detection.