List of Issues

Chinese Journal of Chromatography
2013, Vol. 31, No. 7
Online: 28 July 2013

Previous Issue    Next Issue



For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Select

Development of sample pretreatment approach and technology for peptidome WEI Liming, LU Haojie, YANG Pengyuan, WU Xin 2013, 31 (7):  603-612.  DOI: 10.3724/SP.J.1123.2013.05030 Abstract ( 1216 )   [Full Text(HTML)] () PDF (924KB) ( 426 )   As a branch of proteomics, peptidome has been extensively applied in biomarker discovery, early diagnosis and pharmacy. In the research of peptidome, sample pretreatment plays a vital role. Here, we review the pretreatment approaches and techniques of peptidome, mainly including ultrafiltration, organic solvent precipitation, solid phase extraction and so on. The biggest challenge of the development of peptidome is the large number of high-abundance proteins in the sample. Therefore, there is an urgent need to develop the fast, efficient, high-throughput and automated sample preparation methods and techniques.

Select

Development of sample pretreatment techniques-rapid detection coupling methods for food security analysis HUANG Yichun, DING Weiwei, ZHANG Zhuomin, LI Gongke 2013, 31 (7):  613-619.  DOI: 10.3724/SP.J.1123.2013.04035 Abstract ( 1548 )   [Full Text(HTML)] () PDF (871KB) ( 422 )   This paper summarizes the recent developments of the rapid detection methods for food security, such as sensors, optical techniques, portable spectral analysis, enzyme-linked immunosorbent assay, portable gas chromatograph, etc. Additionally, the applications of these rapid detection methods coupled with sample pretreatment techniques in real food security analysis are reviewed. The coupling technique has the potential to provide references to establish the selective, precise and quantitative rapid detection methods in food security analysis.

Select

Advances in using passive sampling techniques to measure bioavailability and toxicity of organic contaminants in sediment LI Huizhen, YOU Jing 2013, 31 (7):  620-625.  DOI: 10.3724/SP.J.1123.2013.05010 Abstract ( 1111 )   [Full Text(HTML)] () PDF (837KB) ( 269 )   Passive sampling techniques have been used as biomimetic extraction methods to measure the bioavailability and toxicity of organic contaminants in sediment. The advantages and disadvantages of the commonly used passive samplers including semi-permeable membrane device, polyethylene device, polyoxymethylene and solid-phase microextraction are reported. The challenges of using passive samplers in sediment risk assessment are discussed, and the possible solutions and future studies are also proposed.

Select

Application of molecularly imprinted solid phase extraction in the separation and determination of active constituents from natural compounds CHEN Fangfang, SHI Yanping 2013, 31 (7):  626-633.  DOI: 10.3724/SP.J.1123.2013.05026 Abstract ( 1801 )   [Full Text(HTML)] () PDF (883KB) ( 419 )   The active constituents of natural medicine resources are complicated and in low content, which are difficult to be extracted and separated by general methods. Molecularly imprinted polymers are functional porous materials with molecular-specific recognition sites to a particular target molecule. The molecularly imprinted solid phase extraction has been used as a sample preparation technique for the separation of active constituents from natural medicine resources. The target molecules in a mixture of chemical species can be recognized selectively. In this review, the applications of the molecularly imprinted solid phase extraction for the determination and separation of active constituents (e.g. flavonoids, polyphenols, alkaloids, organic acids, phenylpropanoids, terpenoids, etc.) from natural compounds in recent years are summarized.

Select

Progress of sample preparation techniques in gas chromatographic analysis YAN Kuanglin, LIN Liqiong, ZHENG Xiaxi, XIAO Xiaohua, CAO Yujuan 2013, 31 (7):  634-639.  DOI: 10.3724/SP.J.1123.2013.05035 Abstract ( 1397 )   [Full Text(HTML)] () PDF (802KB) ( 407 )   Gas chromatography (GC) is a widely used analytical technique in many fields. Sample preparation is very important in GC analysis due to its time consumed and deviations produced. In the present paper, the progress of some typical sample preparation techniques in gas chromatography, including purge and trap, solid phase extraction, solid phase microextraction, liquid phase microextraction, microwave assisted extraction, ultrasonic-assisted extraction, etc., are reviewed.

Select

Screening of the active ingredients in natural products by capillary electrophoresis and high performance liquid chromatography-mass spectrometry ZHANG Yanmei, KANG Jingwu 2013, 31 (7):  640-645.  DOI: 10.3724/SP.J.1123.2013.03013 Abstract ( 1291 )   [Full Text(HTML)] () PDF (804KB) ( 268 )   A new strategy for screening the crude natural extracts and quickly identifying the bioactive compounds was developed. In combination with high performance liquid chromatography-mass spectrometry (HPLC-MS), the biologically active compounds, such as the enzyme inhibitors, in the crude natural extract can be quickly identified by capillary electrophoresis (CE)-based activity assay. The crude natural extracts were assayed by a CE-based enzyme inhibitor screening method, and the active extract was isolated by HPLC-MS/MS with a semipreparative column. Then, each eluted component was assayed again with the CE-based assay method. Finally, the structures of the identified active compounds were elucidated by MS/MS analysis. Acetylcholinesterase (ACHE), its substrate acetylthiocholine chloride (AThCh), as well as the crude extract of Rhizoma coptidis were utilized for the proof of the methodology. Seven isoquinoline alkaloids, namely jatrorrhizine, epiberberine, columbamine, coptisine, corysamine, palmatine and berberine were identified to be active as the inhibitors of ACHE. Their IC50 values were 40, 442, 38, 182, 419, 54 and 16 μ mol/L, respectively. Compared with the traditional screening methods, the method is characterized with several advantages, such as extremely low sample and reagent consumption, high speed of analysis, high sensitivity of detection, high throughput in terms of preparation of the natural products by HPLC. Overall, the results demonstrate that the method is valuable for the screening of the bioactive compounds in the crude natural extracts.

Select

Inhibitor screening and selectivity assessment against multiple cellular protein kinases by capillary electrophoresis with laser-induced fluorescence detection ZHANG Qianqian, ZHANG Xuepei, ZHANG Hanzhi, KANG Jingwu 2013, 31 (7):  646-655.  DOI: 10.3724/SP.J.1123.2013.04032 Abstract ( 1247 )   [Full Text(HTML)] () PDF (854KB) ( 170 )   A method that can be used for screening protein kinase inhibitors (PKIs) and simultaneously assessing their selectivity is described. The method is based on simultaneously assaying multiple cellular protein kinases by performing capillary electrophoresis (CE) separation and measuring the peak areas of the phosphorylated substrate peptides. The powerful separation capability of CE combined with the highly sensitive and selective laser-induced fluorescence (LIF) detector enables the direct screening of PKIs against cell lysates, which are used as an inexpensive source of enzymes. Four cell lines, three specific substrate peptides labeled with 5-carboxyfluorescein (5-FAM), two relative specific PKIs (TBB and H-89) and one non-specific PKI (staurosporine) were utilized to prove the methodology. With this method, the inhibitory activity of the tested compounds against multiple protein kinases was identified in parallel by comparing the peak areas of the phosphorylated substrates with those obtained in the absence of any inhibitors. The reduced peak area of the phosphorylated substrate definitively represents a positive screening result. Simultaneously, assaying the inhibition of one inhibitor against mutiple cellular protein kinases enables the assessment of its selectivity. Compared to the conventional, single-target screening format, the cell lysate-based multi-target method is more informative, more straightforward and more cost effective.

Select

On-line coupling of ionic liquid-based single-drop microextraction and capillary electrophoresis for determination of three bromophenols in water samples ZHANG Wenhui, JIANG Tingfu, LÜ Zhihua, WANG Yuanhong 2013, 31 (7):  656-660.  DOI: 10.3724/SP.J.1123.2013.05050 Abstract ( 1042 )   [Full Text(HTML)] () PDF (960KB) ( 187 )   An ionic liquid-based single-drop microextraction (IL-SDME) procedure using IL as an extractant on-line coupled to capillary electrophoresis (CE) is proposed. The method is capable of quantifying trace amounts of bromophenols in water samples. The extraction parameters such as extraction solvent, extraction time, ionic liquid single-drop volume, ionic strength and organic solvent were systematically investigated. For the SDME of the three bromophenols, a [C4MIM]PF6] microdrop was exposed for 8 min to the aqueous sample with 10% (w/w) NaCl and then was directly injected into a capillary column for analysis. Under the optimal conditions, good linear relationships were obtained in the concentration range of 1-100 mg/L with the correlation coefficients of 0.9939-0.9988 for the bromophenols. The detection limits of the three bromophenols were 0.3 mg/L. The RSDs of peak areas of the standards were 5.21%-6.47% (n=6). And the enrichment factors for the three bromophenols were 115.8, 327.0 and 569.8. The proposed method was applied to the determination of the three bromophenols in tap, river and lake waters with the recoveries of the three bromophenols in the range of 87.8%-96.7%. The method is suitable for the quantification of bromophenols in water samples.

Select

Determination of amino acids in honey by capillary electrophoresis with indirect ultraviolet detection ZHOU Xianjing, SHI Yanping 2013, 31 (7):  661-666.  DOI: 10.3724/SP.J.1123.2013.05027 Abstract ( 1304 )   [Full Text(HTML)] () PDF (791KB) ( 237 )   A method of capillary electrophoresis with indirect ultraviolet (UV) detection was developed for the separation and determination of nine amino acids such as lysine, tryptophan, glutamic acid, etc. The effects of sodium dihydrogen phosphates concentration, pH of buffer and sample injection type and time on the reproducibility and efficiency were investigated. The optimum injection time was 5 s at 5 kPa. The optimum electrophoretic conditions were as follow: 10 mmol/L sodium dihydrogen phosphates (pH 10.2) containing 0.5 mmol/L cetrimonium bromide, 20 mmol/L nicotinic acid and 10%(v/v) methanol as running buffer, applied voltage of-15 kV, detection wavelength of 220 nm. The base line separation of the nine amino acids was achieved successfully within 11 min. The lowest detection limit was 0.3 mg/L. All of the nine analytes showed good linearities within 1.0-1000 mg/L. The relative standard deviations of migration time and peak area were 0.64%-5.83%. The recoveries of the eight amino acids spiked in a real sample were between 60.00% and 118.37%. The method was applied in the determination of the amino acids in honey samples from different nectar plants and origins. Prolin, serine and aspartic acid were found in five honey samples, and tryptophan was only found in a litchi honey sample. This method can provide good reference to the evaluation of the quality and nectar origin of honey.

Select

Analysis of toxaphene and its eight congeners in sediment and fish tissue by gas chromatography-negative ion mass spectrometry LAO Wenjian 2013, 31 (7):  667-673.  DOI: 10.3724/SP.J.1123.2013.06030 Abstract ( 1069 )   [Full Text(HTML)] () PDF (809KB) ( 137 )   Toxaphene quantification incorporating gas chromatography/negative chemical ionization mass spectrometry (GC/NCI-MS) offers improved sensitivity and specificity. The U.S. Environmental Protection Agency (USEPA) recently released a GC/NCI-MS method (Method 8276) for the measurement of technical toxaphene and eight specific congeners (Hx-Sed, Hp-Sed, P26, P41, P40, P44, P50 and P62). However, there is still lack of a practical and complete analytical method including sample extraction, clean up, instrumental analysis, and data analysis. The goal of this work was to develop a ready-to-use method for the quantification of total toxaphene and the eight congeners. Sediment and salmon fish tissue were selected as sample matrices and extracted with methylene chloride using an accelerated solvent extraction system. The sample extracts were cleaned up with active copper powder or gel permeation chromatography, and finally silica/alumina combination column. Separation was performed on a DB-XLB column. GC/NCI-MS was operated under selected ion monitoring mode with an identical set of confirmation and quantitation ions for total toxaphene and the eight congeners. Oxygen reaction of polychlorinated biphenyls (PCB) was monitored by PCB204, an internal calibration standard, and the reaction level was kept below 1%. Average relative response factors were used in quantitation. Quantitation of total toxaphene employed the sum of all detectable (S/N ≥ 3) 6-Cl to 10-Cl homolog peak areas, while the individual congeners were quantified followed the standard procedures for single analytes. Multi-point calibration solutions ranged from 0.5 (5 for P62) to 500 μ g/L for the individual congeners, and 50 to 500 μ g/L for technical toxaphene, with the lowest calibration levels as lower limits of quantitation. Average congener recovery was (90.8±17.4)% (n=10) in spiked sediment with relative standard deviations of 5.4%-12.8% (n=10), underscoring an excellently accurate and precise method. The method was applied to analyze sediment and fish tissue samples.

Select

Determination of phthalate plasticizers in daily foods and their migration from food packages YANG Youyou, XIE Yunfeng, TIAN Feifei, YANG Yongtan 2013, 31 (7):  674-678.  DOI: 10.3724/SP.J.1123.2013.05001 Abstract ( 1552 )   [Full Text(HTML)] () PDF (914KB) ( 579 )   A total of 16 phthalates in food samples (beverage, milk and wine) were analyzed by gas chromatography-mass spectrometry (GC-MS) combined with the sample preparation of liquid-liquid extraction and dispersive solid-phase extraction (dSPE). The limits of detection (LODs, S/N=3) for the 16 phthalates were fairly good, ranging from 0.005 to 0.025 mg/L. The relative standard deviations (RSDs) of the peak areas were less than 2%, showing good repeatability. In addition, the recoveries of phthalates in various matrices were generally ranging from 60% to 110%. In conclusion, the developed method can help the trace analysis of phthalates in beverage, wine and milk. In order to strictly investigate the migration of phthalates from the daily food packages like plastic wraps and storage bags, iso-octane was used as the simulant of fatty foods. The migration determined using the above optimized method showing the significant migration existing in plastic wraps and some unqualified products in current market is not meeting the national regulations about the migration limits of phthalates.

Select

Isolation and identification of impurities in the natural vitamin E XIE Yunfeng, YANG Youyou, LIU Jiajia, WU Wenhua, YANG Yongtan 2013, 31 (7):  679-683.  DOI: 10.3724/SP.J.1123.2013.05021 Abstract ( 1587 )   [Full Text(HTML)] () PDF (779KB) ( 264 )   Two impurities in the natural vitamin E extracted from oil deodorizer distillate were separated and characterized by high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The impurities were purified and collected by normal-phase HPLC. The accurate masses were determined using FTICR-MS and fragmentation behavior was studied by GC-MS. The results showed that the impurities had identical MS spectra and similar electron impact (EI) fragmentation patterns. Based on the spectra, the structures of the two impurities were proposed as the enantiomers of sesamin. The presented method is rapid and effective, and can be applied for the food safety to the vitamin E manufacturing industry.

Select

An assay for anti-factor Xa activity of low molecular weight heparins by high performance liquid size exclusion chromatography ZHANG Qianqian, KANG Jingwu 2013, 31 (7):  684-690.  DOI: 10.3724/SP.J.1123.2013.04029 Abstract ( 1084 )   [Full Text(HTML)] () PDF (798KB) ( 230 )   The "gold standard" assay for monitoring low molecular weight heparins (LMWHs) activity is the chromogenic-based anti-factor Xa assay. The methodology of an anti-factor Xa assay is that LMWH is added to a known amount of excess factor Xa and excess antithrombin. It will bind to antithrombin and form a triplet complex with factor Xa, inhibiting the activity of factor Xa. However, the residual factor Xa can still hydrolyze chromogenic peptide substrate, releasing the chromophore for photometric detection. The absorbance is inversely proportional to the amount of heparin/LMWH. The results are given in anticoagulant concentration in units/mL of anti-factor Xa, such that high values indicate high levels of anticoagulation and low values indicate low levels of anticoagulation. Herein, a novel assay method for anti-FXa activity of LMWHs using high performance liquid size exclusion chromatography (SEC) is reported, in which antithrombin Ⅲ (ATⅢ) was diluted by the buffer solution contained LMWHs. Subsequently, exogenous FXa and p-nitroaniline coupled peptide substrate were added and incubated for a period, separately. The resulting mixture was separated based on size by SEC, and the free chromophore p-nitroaniline can be detected at an absorption maximum of 385 nm without interference from the absorbance of p-nitroanilide substrates. Moreover, the measurements are not influenced by sample opacity or turbidity, so it is possible to test various complex samples, such as plasma. The assay is robust, sensitive, and cost effective.

Select

Metabonomics study of lung cancer cells based on liquid chromatography-mass spectrometry YU Xinwei, WU Qian, LV Wang, WANG Yan, MA Xiaoqiong, CHEN Zhe, YAN Chao 2013, 31 (7):  691-696.  DOI: 10.3724/SP.J.1123.2012.12039 Abstract ( 1484 )   [Full Text(HTML)] () PDF (834KB) ( 659 )   The metabolic profiles of the polar metabolites and the non-polar metabolites in lung tumor cell lines H358, A549, HCC827, H1299, Calu-3, Calu-1, PC-9 and normal cell line MRC-5 were analyzed separately using high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF/MS). Partial least square discriminant analysis (PLS-DA) was used to process the metabolic data. The results showed that the metabolites of the lung cancer cell lines and normal cell line have significant differences. Further, 10 polar metabolites and 21 non-polar metabolites which had a significant contribution to classification were selected and preliminarily identified due to the accurate mass. Comparing with the normal cell line, the lung tumor cell lines present an abnormal metabolism in protein, fatty acid, and phospholipids. These results may provide important information for the early diagnosis of lung cancer.

Select

Determination of eight defoliant residues in cotton by accelerated solvent extraction coupled with ultra performance liquid chromatography-tandem mass spectrometry WU Gang, DONG Suozhuai, PAN Lulu, ZHAO Shanhong, WANG Lijun, GUO Fanglong, LI Dan 2013, 31 (7):  697-702.  DOI: 10.3724/SP.J.1123.2012.12038 Abstract ( 1530 )   [Full Text(HTML)] () PDF (792KB) ( 252 )   A novel method has been developed for the rapid extraction and determination of eight defoliants including thidiazuron, butiphos, methabenzthiazuron, abscisic acid, carfentrazone-ethyl, diuron, paraquat, and pyrithiobac-sodium in cotton by accelerated solvent extraction (ASE) coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The defoliants in cotton were extracted by ASE and the extracts were dried by a rotavapor, then redissolved in the solvents of acetonitrile and water (1:9, v/v). The chromatographic analysis was performed on an Acquity UPLC® HSS T3 column (50 mm×2.1 mm, 1.8 μ m) by a gradient elution employing of acetonitrile and 0.05% (v/v) formic acid as mobile phases. The analytes were detected by electrospray ionization (ESI) tandem mass spectrometry with multiple reaction monitoring (MRM) in positive ion mode. Good linearities (r >0.99) were observed between 0.01 and 0.3 mg/L for all the compounds. The recoveries and relative standard deviations (RSDs) were obtained by spiking untreated samples with the eight defoliants at 0.1, 0.5 and 1.0 mg/kg. The average recoveries of the eight defoliants were from (84.18±8.04)% to (95.99±6.76)%. The precision values expressed as RSDs were from 7.04% to 10.60% (n=6). The limits of detection were 0.8-29 μ g/kg and the limits of quantification were 2.5-96 μ g/kg for the analytes. The results showed that the method is simple, rapid, sensitive and accurate, and is suitable for the quantitative determination and confirmation of the eight defoliants in cotton.

Select

Determination of zearalanol and related mycotoxins in pork by solid-phase extraction coupled with ultra performance liquid chromatography-tandem mass spectrometry LI Liping, FAN Sai, ZHAO Rong, LI Bing, LIU Wei, WU Guohua 2013, 31 (7):  703-708.  DOI: 10.3724/SP.J.1123.2012.12033 Abstract ( 1152 )   [Full Text(HTML)] () PDF (791KB) ( 211 )   A method was established for the determination of six compounds of zearalanol and related mycotoxins in pork and its products. After hydrolysis of the target compounds in the pork by β-glucosidase/sulfatase, they were extracted with methanol aqueous solution and further purified by an HLB column. The separation was performed on a BEH C18 column with gradient elution using acetonitrile-water as mobile phases. The analytes were determined by mass spectrometry using electrospray ionization (ESI) in negative scan mode and multiple reaction monitoring (MRM) mode. α-Zearalenol-D7 and β-zearalenol-D7 were used as internal standards. The good linearities (r >0.999) were achieved for the six compounds over the range of 1.0-100 μ g/L based on the internal standard calibration. The detection limits of the method were 0.03-0.09 μ g/kg. The mean recoveries of the six target compounds spiked at three levels from 1.0-10.0 μ g/kg ranged from 76.7% to 100.5% with the relative standard deviations (RSDs) less than 20%. The proposed method is simple, sensitive, reproducible, and complies with the regulations for the determination of trace contaminant residues in food matrices.

Select

Simultaneous determination of 23 sedative drugs in health foods by high performance liquid chromatography-tandem mass spectrometry ZHU Lin, RUAN Liping, LIU Hualiang, JI Wenliang, MA Yongjian 2013, 31 (7):  709-713.  DOI: 10.3724/SP.J.1123.2012.12025 Abstract ( 1248 )   [Full Text(HTML)] () PDF (905KB) ( 243 )   An analytical method using HPLC-MS/MS was developed for qualitative and quantitative analysis of 23 sedative drugs in health foods. The method was based on the sonication-assisted extraction of the health food samples using 10 mL methanol. The extract was then isolated by centrifugation and the supernatant was separated on an Agilent Eclipse Plus C18 column with gradient elution at a flow rate of 300 μ L/min. A binary mobile phase was 10 mmol/L ammonium formate (solvent A) and acetonitrile/methanol (1:1, v/v; solvent B). The electrospray ionization (ESI) source in positive ion mode or negative ion mode was used for multiple reaction monitoring (MRM). The external standard method was used for the quantification. The calibration graphs were linear in their concentration ranges with the correlation coefficients more than 0.990. The limits of detection (LOD, S/N=3) were between 0.02-1.0 μ g/L. The recoveries for all the drugs in health foods were 82.3%-114.8% with the relative standard deviations less than 14.1% at three spiked levels. Thirteen kinds of health foods were tested, in which meprobamate and oxazepan were found in one sample separately, and zaleplon was found in two samples. The method is specific, sensitive, easy and quick and suitable for the confirmation and quantification of the 23 sedative drugs in health foods.

Select

Enrichment of cis-diols active components in traditional Chinese medicines by boronate affinity monolithic column HU Qinghong, WANG Chaoran, LI Jing, WANG Yan, GU Xue, YAN Chao 2013, 31 (7):  714-717.  DOI: 10.3724/SP.J.1123.2012.12040 Abstract ( 1347 )   [Full Text(HTML)] () PDF (968KB) ( 221 )   A novel poly(4-vinylphenylboronic acid (VPBA)-co-pentaerythritol triacrylate (PETA)) monolithic column was prepared by thermal-initiated copolymerization of VPBA and PETA in a binary porogen system comprising diethylene glycol and ethylene glycol. The fabricated monolithic column demonstrated good boronate affinity property, which can specifically capture cis-diols containing compounds. We developed such a monolithic column and applied it to enrich active components in Herba Taraxaci and Euonymus acanthocarpus. The extracts of the two traditional Chinese medicines were separated and enriched on μ HPLC by the prepared monolith, and the fractions were collected and examined by HPLC. The results showed that the responses of the corresponding peaks were greatly improved, indicating that the poly(VPBA-co-PETA) monolithic column can be efficiently used to enrich active components in traditional Chinese medicines containing cis-diols group.