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    Chinese Journal of Chromatography
    2015, Vol. 33, No. 3
    Online: 08 March 2015

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    Preparation of 1 μm non-porous C18 silica gel stationary phase for chiral-pressurized capillary electrochromatography
    LU Yangfang, WANG Hui, WANG Guiming, WANG Yan, GU Xue, YAN Chao
    2015, 33 (3):  209-214.  DOI: 10.3724/SP.J.1123.2014.11030
    Abstract ( 661 )   [Full Text(HTML)] () PDF (2522KB) ( 307 )  

    Non-porous C18 silica gel stationary phase (1 μm) was prepared and applied to chiral separation in pressurized capillary electrochromatography (pCEC) for the enantioseparation of various basic compounds. The non-porous silica particles (1 μm) were synthesized using modified Stöber method. C18 stationary phase (1 μm) was prepared by immobilization of chloro-dimethyl-octadecylsilane. Using carboxymethyl-β-cyclodextrin (CM-β-CD) as the chiral additive, the pCEC conditions including the content of acetonitrile (ACN), concentration of buffer, pH, the concentration of chiral additive and flow rate as well as applied voltage were investigated to obtain the optimal pCEC conditions for the separation of four basic chiral compounds. The column provided an efficiency of up to 190000 plates/m. Bupropion hydrochloride, clenbuterol hydrochloride, metoprolol tartrate, and esmolol hydrochloride were baseline separated under the conditions of 5 mmol/L ammonium acetate buffer at pH 4.0 with 20% (v/v) acetonitrile, and 15 mmol/L CM-β-CD as the chiral additive. The applied voltage was 2 kV and flow rate was 0.03 mL/min with splitting ratio of 300:1. The resolution were 1.55, 2.82, 1.69, 1.70 for bupropion hydrochloride, clenbuterol hydrochloride, metoprolol tartrate, esmolol hydrochloride, respectively. The C18 coverage was improved by repeating silylation method. The synthesized 1 μm C18 packings have better mechanical strength and longer service life because of the special, non-porous structure. The column used in pCEC mode showed better separation of the racemates and a higher rate compared with those used in the capillary liquid chromatography (cLC) mode. This study provided an alternative way for the method of pCEC enantioseparation with chiral additives in the mobile phase and demonstrated the feasibility of micron particle stationary phase in chiral separation.

    Preparation and evaluation of glutathione modified SiO2@Au as stationary phase in capillary liquid chromatography and pressurized capillary electrochromatography
    WANG Hui, XUE Yun, LU Yangfang, GU Xue, WANG Yan, YAN Chao
    2015, 33 (3):  215-220.  DOI: 10.3724/SP.J.1123.2014.12002
    Abstract ( 589 )   [Full Text(HTML)] () PDF (11399KB) ( 139 )  

    In order to improve the contents of -NH2 group on the surface of SiO2, polyethylenimine (PEI) was introduced on the surface of SiO2 through Schiff Base reaction. Then self-assembled monolayer electroless plating (SAM-electroless plating) method was used to prepare SiO2@Au core-shell particles. During this process, two factors were discussed. They were the reaction pH in the SiO2@Au seed forming phase and the reaction volume of formaldehyde in the SiO2@Au seed growth phase. The scanning electronic microscopy (SEM) showed the coverage of Au was high and the dispersity was uniform after the optimizations. As we know, Au can coordinate with -SH group easily, so glutathione (GSH) can be bound on the surface of Au. In this study, GSH was bound on the surface of Au through the optimization of the reaction pH. The Fourier transform infrared spectrum showed that the GSH was bound on the surface of Au successfully at pH 3. At last, this packing material was packed into capillary column by slurry packing method to prepare SiO2@Au-GSH capillary columns, and the capillary liquid chromatography (cLC) mode was used to certify the hydrophilic property of this kind of column. In addition, this kind of column was certified to have a good separation ability of polar compounds in pressurized capillary electrochromatography (pCEC) mode.

    Synthesis of core-shell hydrophilic polymer-silica hybrid material and its application in N-glycan enrichment
    BAI Haihong, FAN Chao, SHEN Bingquan, TIAN Fang, DENG Yulin, PAN Yiting, QIN Weijie, QIAN Xiaohong
    2015, 33 (3):  221-227.  DOI: 10.3724/SP.J.1123.2014.11022
    Abstract ( 611 )   [Full Text(HTML)] () PDF (11399KB) ( 170 )  

    Protein N-glycosylation is one of the most important post-translational modifications closely correlated with many important biological and pathological processes. The structural alterations of N-linked glycans in glycoproteins are always associated with many diseases, such as diabetes, heart failure and malignant tumors. Therefore, it is very important to establish sensitive methods for high-throughput N-glycan profiling. However, the low abundance of the N-glycoproteins and the heterogeneity of the N-glycans make it a challenge to analyse the protein glycosylation sensitively. In this work, we had synthesized core-shell hydrophilic polymer-silica hybrid materials (pGMAG-SiO2) for the efficient enrichment of protein N-glycans. Firstly, pGMAG-SiO2 was prepared by in situ growth of glucose polymer on the surface of silica microparticles using surface-initiated atom transfer radical polymerization (SI-ATRP) technique. The strong hydrophilicity of the material makes it suitable for the enrichment of N-glycans released from complex samples. Secondly, maltoheptaose and the N-glycans from chicken egg albumin were used as standard samples to optimize the enrichment conditions and evaluate the enrichment efficiency of pGMAG-SiO2. Finally, pGMAG-SiO2 was applied to the enrichment of N-linked glycans from human plasma proteins and 47 glycoforms were successfully identified after enrichment. These results demonstrated the high enrichment efficiency and significant application value of pGMAG-SiO2 in the analysis of N-glycans.

    Determination of 16 pesticide residues in fruits and vegetables by QuEChERS-liquid chromatography-tandem mass spectrometry
    WU Yan, JIANG Bing, XU Yigang, ZHAO Wei, MENG Xiangrui, ZHOU Yuan, YU Jiahui, ZU Yuangang
    2015, 33 (3):  228-234.  DOI: 10.3724/SP.J.1123.2014.10026
    Abstract ( 660 )   [Full Text(HTML)] () PDF (1062KB) ( 264 )  

    A sensitive and convenient liquid chromatography-tandem mass spectrometric method was developed for the determination of 16 pesticides such as imidacloprid, prochloraz, difenoconazole, azoxystrobin, and thiamethoxam in fruits and vegetables. After compared with methanol and acetone-cyclohexane (1:2, v/v), acetonitrile was chosen as the extraction solvent. The samples were extracted by acetonitrile in high-speed homogenization. The extraction solution was cleaned up by liquid-liquid extraction, and the supernatant was collected. In this work, QuEChERS exhibited much higher efficiency than Carbon-NH2 solid-phase extraction in purification. The pigments and organic acids were removed by purge line (150 mg primary secondary amine (PSA) sorbent and 900 mg absolute magnesium sulfate), leading to the decrease of the background interferences. The average recoveries of the 16 pesticides were almost in the range of 75%-111% at the three spiked levels, and the relative standard deviations were less than 16%. The qualitative analysis and quantitative analysis were investigated by LC-MS/MS and matrix-matched calibration curves. The results showed that the method of QuEChERS combined with LC-MS/MS is rapid, accurate and sensitive for the determination of the 16 pesticide residues in fruits and vegetables.

    Determination of 41 pesticide residues in vegetables by QuEChERS-ultra performance liquid chromatography- tandem mass spectrometry
    LIN Tao, SHAO Jinliang, LIU Xingyong, YANG Dongshun, CHEN Xinglian, LI Yangang, FAN Jianlin, LIU Hongcheng
    2015, 33 (3):  235-241.  DOI: 10.3724/SP.J.1123.2014.11023
    Abstract ( 723 )   [Full Text(HTML)] () PDF (1077KB) ( 420 )  

    A multiresidue analytical method for the rapid determination of 41 pesticide residues in vegetables was developed by using QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), including recessive pesticides, banned pesticides and pesticides with restrict use, plant growth regulators and some other pesticides with high detection rates. The vegetable sample was extracted by 1% (v/v) acetic acid-acetonitrile, cleaned-up by primary secondary amine (PSA) and injected for analysis. The positive and negative ion modes and multiple reaction monitoring (MRM) mode were used in the analysis, and the analytes were quantified by the external standard method. Under the conditions of optimized QuEChERS, chromatography and mass spectrometry, the 41 pesticides showed good linearities in the range of 1.0 μg/L to 100 μg/L, with the correlation coefficients (r2) higher than 0.999. The limits of detection of the method were 0.003 μg/kg to 1.00 μg/kg. The average recoveries of the 41 pesticides in different matrices were in the range of 74.1%-120.4% with the relative standard deviations from 2.8% to 11. 9%. The method has the advantages of rapidity, simplicity, high sensitivity and better purification effect. It is suitable for the rapid determination of the common pesticides in vegetables, and it provides a strong guarantee for the risk assessment of the quality and safety of vegetables.

    Low temperature freezing followed by dispersive solid phase extraction for the determination of 104 pesticide residues in vegetable oils using ultra-performance liquid chromatography-tandem mass spectrometry
    XU Juan, WANG Lan, HUANG Huajun, CHEN Jie, CHEN Wenrui, XIANG Dapeng
    2015, 33 (3):  242-249.  DOI: 10.3724/SP.J.1123.2014.10011
    Abstract ( 689 )   [Full Text(HTML)] () PDF (3406KB) ( 243 )  

    A method using liquid-liquid extraction (LLE) followed by clean-up steps of centrifugation, freezing and dispersive solid phase extraction (D-SPE)and ultra-performance liquid chromatography (UPLC) coupled with tandem mass spectrometry (MS/MS) has been developed for the determination of trace levels of 104 pesticides in vegetable oils. LLE has been optimized to extract these pesticide residues from oils to obtain the highest recoveries of pesticides and the lowest co-extract fat residue in the final extract. In addition, the centrifugation and freezing steps as well as D-SPE with primary secondary amine (PSA), graphite carbon black (GCB) and C18 were used as the clean-up steps to minimize the co-extract fat. The recoveries obtained ranged from 55% to 121% and the relative standard deviations (RSDs) ranged from 0.47% to 19.2% at the spiked levels of 0.01, 0.02 and 0.05 mg/kg. This method, combining with accurate and sensitive detection, allowed quantification and confirmation at levels as low as 1 μg/kg for 80% of the analytes. The limits of quantification (LOQs) of the most compounds were below the maximum residue limits (MRLs) established by the Chinese legislations for oils. The proposed method was applied successfully for the residue determination of the selected pesticides in oils.

    Determination of four frequently-used essences in foods by ultra performance liquid chromatography-tandem mass spectrometry
    YANG Huamei, HANG Li
    2015, 33 (3):  250-255.  DOI: 10.3724/SP.J.1123.2014.11018
    Abstract ( 799 )   [Full Text(HTML)] () PDF (948KB) ( 236 )  

    A method has been developed for the simultaneous determination of vanillin, ethyl vanillin, maltol and ethyl maltol in foods by ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). The sample was extracted with ultrapure water, and purified with SPE column. The target compounds were separated on a C18 column with the gradient elution of methanol and water containing 0.002 mol/L ammonium acetate and 0.1%(v/v) formic acid. The four components were determined in the modes of electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM). The linear ranges were 10-1000 μg/L for vanillin and maltol and 5-500 μg/L for ethyl vanillin and ethyl maltol, with the correlation coefficients more than 0.999. The recoveries of the four compounds ranged from 75.8% to 116%, with the relative standard deviations (RSDs) of 1.58%-4.01%. The method showed good extraction efficiency, high sensitivity and good reproducibility. It is suitable for the simultaneous detection of vanillin, ethyl vanillin, maltol and ethyl maltol in foods.

    Fast screening of 24 sedative hypnotics illegally added in improving sleep health foods by high performance liquid chromatography-ion trap mass spectrometry
    LU Li, GONG Xu, TAN Li
    2015, 33 (3):  256-266.  DOI: 10.3724/SP.J.1123.2014.11001
    Abstract ( 591 )   [Full Text(HTML)] () PDF (1074KB) ( 270 )  

    A fast screening method was established for the simultaneous determination of 24 sedative hypnotics illegally added in improving sleep health foods by high performance liquid chromatography-ion trap mass spectrometry (HPLC-IT MS). The method was based on the sonication assisted extraction of the improving sleep health food samples using methanol. The extract was then filtrated with 0.45 μm filter membrane and the filtrate was separated on a Phenomenex Luna C18 column with isocratic elution at a flow rate of 0.3 mL/min. A binary mobile phase was 0.05% (v/v) formic acid (solvent A)-methanol/acetonitrile (15:25, v/v, solvent B). The electrospray ionization (ESI) source in positive ion mode or negative ion mode was used to scan MS1-MS3 spectra for the 24 sedative hypnotics. The MS2 and MS3 spectra were used for qualitative analysis of samples. The calibration graphs were linear in their concentration ranges with the correlation coefficients (r2) more than 0.999. The limits of detection (LODs) were 4.0-446.6 μg/L. The recoveries for all the drugs in the improving sleep health foods were 88.6%-110.3% with the relative standard deviations no more than 9.8% at three spiked levels. Twenty-seven batches of the improving sleep health foods were tested. Melatonin was found in eighteen batches. The method is fast, specific, sensitive, easy and suitable for fast screening of 24 sedative hypnotics illegally added in improving sleep health foods.

    Simultaneous determination of 33 primary aromatic amines in polystyrene and polyethylene masterbatches for foods by ultra-performance liquid chromatography- tandem mass spectrometry
    MAN Zhengyin, WANG Quanlin, LI Hesheng, ZHANG Aizhi, SHEN Jian
    2015, 33 (3):  267-274.  DOI: 10.3724/SP.J.1123.2014.11025
    Abstract ( 522 )   [Full Text(HTML)] () PDF (869KB) ( 256 )  

    A comprehensive analytical method based on ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-MS/MS) has been developed for the simultaneous determination of 33 primary aromatic amines (PAAs) in polystyrene (PS) and polyethylene (PE) masterbatches for foods. The PS masterbatches were dissolved with dichloromethane, and methanol was added to precipitate after extraction by ultrasound extraction. Then the extract was purified by passing through a carbon graphite solid phase extraction column. The PE masterbatches were swelled and extracted with dichloromethane by ultrasound. The purified PS solution and PE extract were concentrated, and diluted to 2 mL with methanol-water (1:9, v/v), and filtered through the membranes of 0.22 μm before UPLC-MS/MS analysis. The analytes were separated on a BEH Phenyl column (100 mm×2.1 mm, 1.7 μm), eluted by gradient with 0.07% (v/v) formic acid in methanol-water (1:9, v/v). The PAAs were detected by UPLC-MS/MS under multiple reaction monitoring (MRM) mode and quantified by the internal standard method. The separation conditions, fragment voltages and collision energies were optimized. The impacts of extraction times, extraction solvents and concentration methods on recoveries were studied. The limits of detection for the 33 primary aromatic amines were 6-10 μg/kg, and the limits of quantitation were 20-30 μg/kg. The mean recoveries of the two different masterbatch products at three spiked levels of 20, 100, 200 μg/kg were 61.3%-119.8%, and the relative standard deviations were 1.4%-14.8%. The experimental results indicated that the method is simple, rapid, sensitive, accurate, and can meet the related requirements for determination.

    Determination of 25 quinolones in cosmetics by liquid chromatography-tandem mass spectrometry
    LIN Li, ZHANG Yi, TU Xiaoke, XIE Liqi, YUE Zhenfeng, KANG Haining, WU Weidong, LUO Yao
    2015, 33 (3):  275-281.  DOI: 10.3724/SP.J.1123.2014.10029
    Abstract ( 611 )   [Full Text(HTML)] () PDF (1400KB) ( 273 )  

    An analytical method was developed for the simultaneous determination of 25 quinolones, including danofloxacin mesylate, enrofloxacin, flumequine, oxloinic acid, ciprofloxacin, sarafloxacin, nalidixic acid, norfloxacin, and ofloxacin etc in cosmetics using direct extraction and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Cosmetic sample was extracted by acidified acetonitrile, defatted by n-hexane and separated on Poroshell EC-C18 column with gradient elution program using acetonitrile and water (both containing 0.1% formic acid) as the mobile phases and analyzed by LC-ESI-MS/MS under the positive mode using multiple reaction monitoring (MRM). The interference of matrix was reduced by the matrix-matched calibration standard curve. The method showed good linearities over the range of 1-200 mg/kg for the 25 quinolones with good linear correlation coefficients (r≥0.999). The method detection limit of the 25 quinolones was 1.0 mg/kg, and the recoveries of all analytes in lotion, milky and cream cosmetics matrices ranged from 87.4% to 105% at the spiked levels of 1, 5 and 10 mg/kg with the relative standard deviations (RSD) of 4.54%-19.7%(n=6). The results indicated that this method is simple, fast and credible, and suitable for the simultaneous determination of the quinolones in the above three types of cosmetics.

    Simultaneous determination of 38 limited colorants in cosmetics by high performance liquid chromatography
    MAO Xiqin, LI Chunling, REN Guojie, ZHANG Guocui, LI Xiaofei, LI Peng
    2015, 33 (3):  282-290.  DOI: 10.3724/SP.J.1123.2014.11017
    Abstract ( 522 )   [Full Text(HTML)] () PDF (874KB) ( 297 )  

    A method has been established for the simultaneous determination of 38 limited colorants in cosmetics by high performance liquid chromatography (HPLC). The samples were extracted by ultrasonic with tetrahydrofuran, methanol, ammonium acetate solution as extraction solvents. After centrifugation, nitrogen blow and redissolved in turn, the extracts were separated on an Agilent zorbax SB-Aq column (150 mm×3.0 mm, 3.5 μm) using a gradient elution program with acetonitrile and 30 mmol/L ammonium acetate containing 0.075% (v/v) formic acid as mobile phases. The detection wavelengths were set at 254, 416, 484, 514, 590 and 620 nm. The linear ranges of the 38 target compounds were all in the range of 1 to 10 mg/L with correlation coefficients more than 0.999. The limits of quantification (LOQs) for the 38 colorants were in the range of 5-50 μg/g. The average recoveries at two spiked levels ranged from 93.2% to 107.6% with the relative standard deviations (RSDs) less than 10% (n=6). This method is accurate, simple, sensitive and reliable, and can be used for the analysis of the 38 limited colorants in cosmetics.

    Simultaneous determination of vitamins A, D3 and E in infant formula and adult nutritions by online two-dimensional liquid chromatography
    ZHANG Yanhai, QIBULE Hasi, JIN Yan, WANG Jia, MA Wenli
    2015, 33 (3):  291-297.  DOI: 10.3724/SP.J.1123.2014.11009
    Abstract ( 571 )   [Full Text(HTML)] () PDF (1255KB) ( 448 )  

    A rapid method for the simultaneous determination of vitamins A, D3 and E in infant formula and adult nutritions has been developed using online two-dimensional liquid chromatography (2D-LC). First of all, C8 and polar embedded C18 columns were chosen as the first and second dimensional column respectively according to hydrophobic-subtraction model, which constituted excellent orthogonal separation system. The detection wavelengths were set at 263 nm for vitamin D3, 296 nm for vitamin E and 325 nm for vitamin A. The purification of vitamin D3 and quantifications of vitamins A and E were completed simultaneously in the first dimensional separation using the left pump of Dual Gradient LC (DGLC) with methanol, acetonitrile and water as mobile phases. The heart-cutting time window of vitamin D3 was confirmed according to the retention time of vitamin D3 in the first dimensional separation. The elute from the first dimensional column (1-D column) which contained vitamin D3 was collected by a 500 μL sample loop and then taken into the second dimensional column (2-D column) by the right pump of DGLC with methanol, acetonitrile and water as mobile phases. The quantification of vitamin D3 was performed in the second dimensional separation with vitamin D2 as internal standard. At last, this method was applied for the analysis of the three vitamins in milk powder, cheese and yogurt. The injected sample solution with no further purification was pre-treated by hot-saponification using 1.25 kg/L KOH solution and extracted by petroleum ether solvent. The recoveries of vitamin D3 spiked in all samples were 75.50%-85.00%. There was no statistically significant difference for the results between this method and standard method through t-test. The results indicate that vitamins A, D3 and E in infant formula and adult fortified dairy can be determined rapidly and accurately with this method.

    Determination of total cyanides and sulfides in wastewater using ion chromatography coupled with ultraviolet photo-dissociation/gas-membrane diffusion
    LU Keping
    2015, 33 (3):  298-303.  DOI: 10.3724/SP.J.1123.2014.08002
    Abstract ( 625 )   [Full Text(HTML)] () PDF (1302KB) ( 284 )  

    An automated system for the determination of total cyanides and sulfides in wastewater has been developed using flow injection, ultraviolet (UV) photo-dissociation, gas-membrane diffusion, column trapping, ion chromatography separation and pulsed amperometric detection. When the sample was mixed with sulfuric acid and hypophosphorous acid medium containing the appropriate amount of sulfamic acid, ascorbic acid, EDTA and citric acid, metal-cyanide complexes such as Fe(CN)63- can be photo-dissociated by 312 nm UV light, which results in hydrogen cyanide (HCN) and similarly, sulfides release hydrogen sulfide (H2S). These products were diffused through a 0.45 μm hydrophobic porous polypropylene membrane and were then absorbed in the dilute NaOH solution, concentrated with a Metrosep A PCC 1 HC/4.0 column, separated on an IonPac AS7 column, and finally detected by the pulsed amperometric detector with Ag electrode. The total cyanides and sulfides were good linear in the range of 0.5-1000 μg/L with correlation coefficients of 0.9989 and 0.9997 respectively. The recoveries were 93%-102% and the limits of detection were 0.5 μg/L for total cyanides and 1.0 μg/L for sulfides under the conditions of the sample volume of 100 μL and the signal to noise ratio of 5. The sample throughput of the system was six samples per hour. The results from this new method have been compared with the ones obtained with the standard method, which shows a good agreement.

    Ultrasound-assisted low-density solvent dispersive liquid- liquid microextraction for the determination of eight drugs in biological samples by gas chromatography- triple quadrupole mass spectrometry
    MENG Liang, ZHU Binling, ZHENG Kefang, ZHANG Wenwen, MENG Pinjia
    2015, 33 (3):  304-308.  DOI: 10.3724/SP.J.1123.2014.12001
    Abstract ( 640 )   [Full Text(HTML)] () PDF (1077KB) ( 260 )  

    A novel microextraction technique based on ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) has been developed for the determination of multiple drugs of abuse in biological samples by gas chromatography-triple quadrupole mass spectrometry (GC-QQQ-MS). A total of 100 μL of toluene as extraction solvent was dropped into the sample solution. Then the mixture was sonicated drastically in an ultrasonic bath for 3 min with occasional manual shaking to form a cloudy suspension. After centrifugation at 10000 r/min for 3 min, the upper layer of low-density extractant was withdrawn and injected into the GC-QQQ-MS for analysis. The parameters affecting extraction efficiency have been investigated and optimized. Under the optimum conditions, good linearities were observed for all analytes with the correlation coefficients ranging from 0.9984 to 0.9994. The recoveries of 79.3%-100.3% with RSDs<5.7% were obtained. The LODs (S/N=3) were in the range from 0.05 to 0.40 μg/L. UA-LDS-DLLME technique has the advantages of less extraction time, suitable for batches of sample pretreatment simultaneously, and higher extraction efficiency. It was successfully applied to the analysis of amphetamines in real human urine samples.

    Direct quantitative analysis of amino acids in fermented beverage of plant extract using high performance liquid chromatography-tandem mass spectrometry
    ZHENG Zhong, SUN Qi, SHI Yongwei, QU Jiale, SONG Fengrui, LIU Zhiqiang
    2015, 33 (3):  309-313.  DOI: 10.3724/SP.J.1123.2014.10010
    Abstract ( 598 )   [Full Text(HTML)] () PDF (802KB) ( 399 )  

    A method was established for underivatized amino acid determination in fermented beverage of plant extract. Samples were diluted with methanol for five times, extracted by ultrasonic vibration for 30 min, and high-speed centrifuged for 15 min at 10000 r/min. The supernatant was separated and detected by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The chromatographic column was Venusil ASB C18 (250 mm×4.6 mm, 5 μm). The elution was performed at a flow rate of 0.5 mL/min using the mobile phases of methanol-acetic acid-water mixture. The MS detector was set as follows: ion source voltage 3 kV, ion source temperature 150 ℃, solvent temperature 350 ℃, gas flow rate 800 L/h. The collision gas was argon with a pressure of 0.17 Pa. The quantitation analysis was carried out with peak area in extracted ion chromatograms. Good linearities were acquired in the range of 0.5-200 μmol/L (r2>0.99) for the amino acids. The recoveries were between 86% and 110%. There were 16 amino acids in the fermented beverage of plant extract quantitatively analyzed. The method is simple, rapid, accurate and reliable in quantitative analysis of amino acid samples in the fields of pharmaceutical, food and natural products.

    Relative molecular mass determination of phenolated depolymerized sodium lignosulfonate by advanced polymer chromatography system
    CUI Peng, FANG Hongxia, WU Qianglin, QIAN Chen
    2015, 33 (3):  314-317.  DOI: 10.3724/SP.J.1123.2014.10030
    Abstract ( 671 )   [Full Text(HTML)] () PDF (776KB) ( 327 )  

    Advanced polymer chromatography (APC) is a newly developed high resolution polymer characterization technique. Within 10 min, it can separate polymers with high resolution and obtain the average relative molecular mass distribution parameters of the polymers. The Mr distribution of the depolymerized lignin product was well characterized with low relative standard deviation (RSD less than 1%) by APC system using ACQUITY AQ 450 Å, 200 Å, and 45 Å columns in series, with 10 μL injection volume, and weak alkaline phosphate buffer solution as the aqueous mobile phase at a flow rate of 0.5 mL/min. Compared with traditional gel permeation chromatography (GPC), the APC system had the advantages of high sensitivity and good reproducibility. The technique to determine the average relative molecular mass distribution of depolymerized lignin oligomers in aqueous phase described in this paper will pave the way for new methods to separate and analyze high performance natural materials, and the feasible method for the investigation of the mechanism of depolymerization and the regulation for liquefied lignin would also be established.

    Analysis of the components of floral scent in Glochidion puberum using gas chromatography-mass spectrometry with dynamic headspace adsorption
    HUANG Daihong, ZHANG Zhenguo, CHEN Guoping, LI Houhun, SHI Fuchen
    2015, 33 (3):  318-322.  DOI: 10.3724/SP.J.1123.2014.11005
    Abstract ( 732 )   [Full Text(HTML)] () PDF (792KB) ( 434 )  

    The floral scent plays the important key role in maintaining the obligate pollination mutualism between Glochidion plants and Epicephala moths. In the study, the dynamic headspace adsorption technique was employed to collect the floral scent emitted by Glochidion puberum, gas chromatography coupled with mass spectrometry (GC-MS) was used for the detection and identification of volatile chemical components in headspace samples of flowers from G. puberum. The peak area normalization was used to determine the relative contents of each odour component. The results showed that 45 compounds mainly consisting of monoterpenes and sesquiterpenes were isolated from the floral scent produced by G. puberum. Especially, both linalool (38.06%) and β-elemene (23.84%) were considered as the major scent components of G. puberum. It was speculated that linalool and β-elemene may be the two potential compounds attracting female Epicephala moths. The study provided the basic data for further electroantennographic detection and bioassays to identify the compounds having the actual physiological activity to female Epicephala moths.

    Simultaneous determination of five hypertoxic rodenticides in serum by gas chromatography-mass spectrometry
    HUANG Huiqiu, HUANG Xun, YU Jingsun
    2015, 33 (3):  323-328.  DOI: 10.3724/SP.J.1123.2014.11024
    Abstract ( 745 )   [Full Text(HTML)] () PDF (825KB) ( 201 )  

    A fast analytical method based on gas chromatography-mass spectrometry (GC-MS) was established for the simultaneous determination of tetramine, fluoroacetamide, sodium fluoroacetate, gliftor Ⅰ and gliftor Ⅱ in serum. At pH 2.0, sodium fluoroacetate was derivatizated at room temperature for 5 min by using N,N-diethyl-p-phenylenediamine as the derivatization reagent and N,N'-dicyclohexylcarbodiimide as the catalyst. The derivative and other rodenticides were extracted with ethyl acetate and concentrated with nitrogen at 50 ℃, then determined by GC-MS in selected ion monitoring (SIM) mode, and quantified with matrix-match standard solutions. The analysis was carried out on an ionic liquid chromatographic capillary column (SLB-IL59, 30 m×0.25 mm×0.20 μm, maximum temperature 300 ℃) at a flow rate of 1.0 mL/min, and the five rodenticides were successfully separated in 15 min when temperature programming was used. The results showed that the calibration curves were linear in the range of 0.01-1.0 mg/L, except for fluoroacetamide (0.02-2.0 mg/L) and tetramine (0.02-10 mg/L), with correlation coefficients (R2) greater than 0.995, and the limits of detection (LODs) were 0.001-0.002 mg/L (S/N=3). The recoveries were 84.0%-110.0% at three different spiked levels, and the relative standard deviations (RSDs) were 2.9%-7.5%(n=6). The method is simple, accurate, highly sensitive and suitable for the detection of the five hypertoxic rodenticides in serum for toxicological purposes.