Loading...

List of Issues

    Chinese Journal of Chromatography
    2015, Vol. 33, No. 5
    Online: 08 May 2015

    For Selected: Toggle Thumbnails
    Solid-phase extraction based on mesoporous Fe3O4@mSiO2@Cu2+ magnetic nanoparticles coupled with high performance liquid chromatography for the determination of microcystins in water samples
    SUN Hong, LOU Dawei, LIAN Lili, HAN Xue, GUO Tingxiu, CHEN Huijun
    2015, 33 (5):  449-454.  DOI: 10.3724/SP.J.1123.2015.01009
    Abstract ( 735 )   [Full Text(HTML)] () PDF (2720KB) ( 176 )  

    Mesoporous magnetic nanoparticles of Fe3O4@mSiO2@Cu2+ were synthesized by two methods of hydrothermal synthesis and room temperature synthesis. The synthesized mesoporous Fe3O4@mSiO2@Cu2+ nanoparticles presented uniform sizes, good magnetic properties and specific selectivity. In this work, a novel magnetic solid-phase extraction (MSPE) method based on mesoporous Fe3O4@mSiO2@Cu2+ nanoparticles (NPs) coupled with high performance liquid chromatography (HPLC) was developed for the simultaneous extraction of trace amount of microcystin-LR (MC-LR) in water samples. The MSPE extraction conditions and HPLC conditions were optimized. The results showed that good linear relationship (r=0.9994) was obtained between peak area and mass concentration of MC-LR in the range of 0.1-15 μg/L. The limit of detection was 0.025 μg/L, and the limit of quantification was 0.082 μg/L. Furthermore, this method was used for the analysis of algal toxins in water samples with the recovery of 78%. The results indicated that Fe3O4@mSiO2@Cu2+ magnetic nanoparticles were good pretreatment alternatives for the concentration of microcystin-LR in water samples.

    Modification of sol-gel hybrid monolith and its application in determination of polycyclic aromatic hydrocarbons
    YANG Rancun, ZHANG Shaowen, SUN Yu'an
    2015, 33 (5):  455-460.  DOI: 10.3724/SP.J.1123.2015.01025
    Abstract ( 556 )   [Full Text(HTML)] () PDF (3265KB) ( 113 )  

    A C6-silica hybrid monolithic column was prepared by click reaction with capillary silica monolith. Firstly, an azide-functionalized silica monolithic column was synthesized via sol-gel reaction with tetramethoxysilane (TMOS) and 3-azidopropyltrimethoxysilane (N3PTMS). Then 1-hexyne was covalently immobilized on the capillary monolith by the "azide-alkyne" click reaction to form C6-silica hybrid monolithic column. As an extraction media of polycyclic aromatic hydrocarbons (PAHs), the conditions for the preparation and modification of the monolith were carefully investigated according to the extraction efficiency. The enrichment factors for typical PAHs: naphthalene, phenanthrene, pyrene and benzo[a]pyrene finally reached 95.9, 114.2, 103.2 and 57.8, respectively. The relative standard deviations (RSDs) for the extraction were lower than 5.5% (intra-day, n=8) and 7.3% (inter-day, n=10). Based on the in-tube solid phase microextraction (in-tube SPME), a new determination method for 16 PAHs was developed with high performance liquid chromatography (HPLC). The limits of detection (LODs, S/N=3) were 0.08-3.72 μg/L and the limits of quantification (LOQs, S/N=10) were 0.26-12.40 μg/L for the PAHs. The spiked recoveries for the PAHs in soil samples were between 82.4% and 110.6% with the RSDs (n=3) of 2.6%-7.9%. Comparison with the method of United States Environmental Protection Agency (U. S. EPA) for the PAHs determination in soil samples, the results showed good accuracy and high consistency. And the high extraction efficiency with high sensitivity and convenience was also demonstrated in the applications of the new approach.

    Preparation and chromatographic performance of a eugenol-bonded silica gel stationary phase for high performance liquid chromatography
    XU Lili, ZHONG Minghua, CHEN Xiaojing
    2015, 33 (5):  461-467.  DOI: 10.3724/SP.J.1123.2015.01039
    Abstract ( 782 )   [Full Text(HTML)] () PDF (1081KB) ( 128 )  

    A eugenol-bonded silica gel stationary phase (EGSP) for high performance liquid chromatography (HPLC) has been synthesized by the solid-liquid successive reaction method. The preparation process included two steps: firstly, γ-glycidoxypropyltrimethoxy-silane (KH-560) was covalently attached to the surface of spherical silica gel. Then the bonded silica gel continued to react with eugenol ligand, which was a plant active component, and obtained EGSP. The structure of EGSP was characterized by elemental analysis, thermogravimetric analysis and Fourier transform infrared spectroscopy. Using naphthalene as a probe, the column efficiency was tested under the mobile phase of acetonitrile-water (35:65, v/v) at a flow rate of 0.8 mL/min. The chromatographic properties and the retention mechanism of EGSP were evaluated by using neutral, basic and acidic analytes as solute probes. Meanwhile, the comparative study with C18 column and phenyl column was also carried out under the same chromatographic conditions. The result showed that the eugenol ligand was successfully bonded to the surface of silica gel with a 0.28 mmol/g of bonded amount, and the theoretical plate number of EGSP column was about 24707 N/m. The EGSP appeared to be a kind of excellent reversed-phase stationary phase with suitable hydrophobicity and various synergistic sites. The eugenol ligand bonded on silica gel could first provideπ-πinteraction sites for different analytes because of its benzene ring and alkenyl. In addition, the methoxy groups of eugenol were responsible for dipole-dipole and hydrogen-bonding interactions between the ligand and solutes in the effective separation process. Comparing with traditional C18 column and phenyl column, EGSP has an advantage in the fast separation of polar compounds under simple experimental conditions.

    Preparation of molecularly imprinted polymers using dummy template and the applications in selective solid-phase extraction of seven bisphenols from human urine, bovine serum and beer samples
    YANG Jiajia, LI Yun, WANG Jincheng, SUN Xiaoli, CHEN Jiping
    2015, 33 (5):  468-474.  DOI: 10.3724/SP.J.1123.2015.02065
    Abstract ( 662 )   [Full Text(HTML)] () PDF (6010KB) ( 190 )  

    A molecularly imprinted polymer (MIP) for selective recognition of seven bisphenols (BPs) was prepared using dummy template phenolphthalein (PP) by bulk polymerization. The characterization results of scanning electron microscopy and nitrogen adsorption-desorption measurements showed that the prepared PP-MIP possessed narrow particle diameter distribution (40-60 μm), a specific surface area (SBET) of 359.77 m2/g and a total pore volume (Vt) of 0.730 cm3/g. The adsorption capacity for bisphenol A (BPA) of PP-MIP was evaluated by static adsorption experiment. And the Scatchard analysis revealed that the maximum specific adsorption capacity of PP-MIP was 4.661 μmol/g. Good class selectivity for BPA and its six structural analogues of bisphenol B (BPB), bisphenol E (BPE), bisphenol AF (BPAF), bisphenol S (BPS), bisphenol AP (BPAP) and bisphenol Z (BPZ) was demonstrated by the chromatographic evaluation experiment. The prepared PP-MIP was successfully used as solid-phase extraction (SPE) sorbent for the separation and purification of the seven BPs in human urine, bovine serum and beer samples. Meanwhile, an accurate and sensitive MIP-SPE-HPLC method was established for the determination of the seven BPs in human urine, bovine serum and beer samples. The limits of detection (LODs) for the three samples were in the range of 1.2-2.0 μg/L. The results showed that good linearities were obtained in the range of 0.02-2 mg/L for the seven BPs and the correlation coefficients (r) were higher than 0.9998. The recoveries of the BPs spiked in blank samples at two spiked levels (100 and 500 μg/L for each BP) were in the range of 90.1%-107.1% with the RSDs≤8.1%. The proposed method is simple and reliable for the rapid detection of the seven BPs in human urine, bovine serum and beer samples.

    Preparation and adsorption characteristics of surface-imprinted polymer using bovine serum albumin and lysozyme as double template proteins
    GAI Qingqing, QU Feng
    2015, 33 (5):  475-480.  DOI: 10.3724/SP.J.1123.2015.01008
    Abstract ( 683 )   [Full Text(HTML)] () PDF (1149KB) ( 149 )  

    The double template surface-imprinted polymer (Bi-MIP) was synthesized by atom transfer radical polymerization (ATRP) in aqueous media, using bovine serum albumin (BSA) and lysozyme (Lyz) as the template proteins, N-isopropylacrylamide (NIPAAm) and acrylamide (AAm) as the monomers and N-[3-(dimethylamino)propyl]-methacrylamide (DMAPMA) as the assistant of basic functional monomer. The ATRP possessed the mild reaction conditions and can be initiated at room temperature without heating and ultraviolet radiations. The preparation conditions of imprinted polymer were optimized, and the content of DMAPMA as the assistant of basic functional monomer was investigated. The results showed that Bi-MIP exhibited the good adsorption capacity and selectivity in single protein solution and in mixed protein solution when the volume of DMAPMA in the preparation process of Bi-MIP was 20 μL. The rebinding capacity of Bi-MIP was evaluated according to adsorption isotherm of the imprinted polymer. The Langmuir adsorption model was employed to describe the isotherms and revealed that Bi-MIP exhibited the maximum rebinding to BSA and Lyz at 10.2 mg/g and 19.2 mg/g, respectively. And Bi-MIP had good imprinting effect and adsorption capacity to templates BSA and Lyz from egg white and bovine serum samples. This will provide a new way for specific recognition of the double/multiple target proteins in the complex biological samples.

    Preparation and characterization of core-shell structural magnetic molecularly imprinted polymers for nafcillin
    CHEN Langxing, LIU Yuxing, HE Xiwen, ZHANG Yukui
    2015, 33 (5):  481-487.  DOI: 10.3724/SP.J.1123.2014.12040
    Abstract ( 682 )   [Full Text(HTML)] () PDF (3913KB) ( 125 )  

    The uniform core-shell nanostructured magnetic molecularly imprinted polymers (MIPs) were synthesized using antibiotic nafcillin as a template. In this protocol, the magnetite nanoparticles (NPs) were synthesized by the solvothermal reaction firstly. Subsequently, the vinyl groups were grated onto silica-modified Fe3O4 surface by 3-methacryloyloxypropyltrimethoxysilane via sol-gel method. Finally, the nafcillin-MIPs film was formed on the surface of Fe3O4@SiO2 by the copolymerization of vinyl end group with functional monomer, methacrylic acid, cross-linking agent, ethylene glycol dimethacrylate, the initiator azo-bis-isobutyronitrile and template molecule. The morphological and magnetic characteristics of the MIPs were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometer. The obtained spherical magnetic MIPs with diameters of about 320 nm had good monodispersity. The static binding experiment was carried out to evaluate the properties of magnetic MIPs and non imprinted polymers (NIPs). The results demonstrated that the magnetic MIPs had high adsorption capacity to template and good selectivity. The imprinting factor and the maximum adsorption capacity of Fe3O4@MIPs to nafcillin were 2.46 and 50.7 mg/g, respectively. It is expected that the prepared magnetic MIPs could be used for the enrichment of nafcillin in complex samples.

    Recent development in petroleomics based on the high-resolution mass spectrometry
    SONG Chunxia, LIU Yingrong, LIU Zelong, WANG Wei, TIAN Songbai
    2015, 33 (5):  488-493.  DOI: 10.3724/SP.J.1123.2015.01016
    Abstract ( 700 )   [Full Text(HTML)] () PDF (1786KB) ( 191 )  

    As the increase of the remaining reserves of the heavier/sourer crude oil and the requirement of the clean energy, it is significant to sufficiently characterize the molecular composition of the petroleum for the selection of the refining processes and the realization of the economic value of the crude oil. Petroleomics, which is based on the high-resolution mass spectrometry platform, is a powerful tool to achieve this goal. In this paper, the analytical technology applied in petroleomics and its most recent development are reviewed, and the perspective of petroleomics is also discussed.

    Determination of perfluoroalkyl acids in lamb liver by high performance liquid chromatography-tandem mass spectrometry combined with dispersive solid phase extraction
    ZHU Pingping, YUE Zhenfeng, ZHENG Zongkun, ZHANG Yi, LI Wenyin, ZHAO Fengjuan, XIAO Chengui, BAI Runye, LIN Wei
    2015, 33 (5):  494-500.  DOI: 10.3724/SP.J.1123.2014.12034
    Abstract ( 651 )   [Full Text(HTML)] () PDF (2041KB) ( 446 )  

    A method was developed for the determination of 19 perfluoroalkyl acids (PFAs) in lamb liver by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) combined with dispersive solid phase extraction. The sample was extracted with acidified acetonitrile, and then cleaned-up by a mixture of N-propylethylenediamine (PSA), C18 and graphitized carbon black (GCB) sorbents. The 19 PFAs were analyzed by HPLC-MS/MS with a C18 chromatographic column, adopting the multiple reaction monitoring (MRM) mode with negative electrospray ionization. The effects of the dosages of hydrochloric acid and the sorbents on the recoveries of the 19 PFAs were studied. For accurate quantitative analysis, the isotope internal standard method was used. The calibration curves were linear with the correlation coefficients over 0.998 in the range of 0.05-20 μg/kg for the 19 PFAs. The limits of detection were 0.004-0.111 μg/kg. The limits of quantification were 0.012-0.370 μg/kg. The mean recoveries of the 19 PFAs at spiked levels of 0.5, 1.0, 2.0 μg/kg were in the range from 80% to 128% with the relative standard deviations of 0.31%-11.1%. The developed method is rapid, simple, accurate. It is suitable for the determination of the 19 PFAs in large quantities of lamb liver samples.

    Determination of 32 sulfonylurea herbicide residues in sweet corns and green soybeans by QuEChERS-liquid chromatography-tandem mass spectrometry
    WANG Lianzhu, HUANG Xiaoyan, WANG Dengfei, CHEN Yong, XU Dunming, ZHOU Yu
    2015, 33 (5):  501-507.  DOI: 10.3724/SP.J.1123.2014.12043
    Abstract ( 786 )   [Full Text(HTML)] () PDF (1069KB) ( 259 )  

    A fast method based on QuEChERS methodology for the simultaneous determination of 32 sulfonylurea herbicide residues in sweet corns and green soybeans was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The clean-up effects of three dispersive sorbents were evaluated in terms of the residue mass for extracts after evaporation and recoveries. The three sorbents were C18, a mixture of two sorbents silica coated with zirconium dioxide (Z-Sep) and C18, a bonded C18 zirconia-coated silica (Z-Sep+). As a result, the best effects were obtained from using Z-Sep/C18 sorbents. The samples were extracted with acetonitrile, and salted out with anhydrous magnesium sulphate and sodium chloride. The extracts were cleaned up with dispersive solid phase extraction using Z-Sep/C18 sorbents. Chromatographic analysis was carried out using a CSH C18 column with gradient elution. The pesticides were analyzed by negative electrospray ionization tandem mass spectrometry under scheduled multiple reaction monitoring mode. The quantification was achieved using matrix-matched standard calibrations as the external standard. The recoveries at fortification levels of 10, 20, 100 μg/kg in sweet corns and green beans ranged from 80.0% to 108.2% with the relative standard deviations of 1.2%-13.0%. The limits of quantification (S/N≥10) were 0.2-5.0 μg/kg. The method has been proven to be simple, sensitive, environmental, and thus suitable for the determination of the 32 sulfonylurea herbicide residues in sweet corns and green soybeans.

    Determination of 14 aniline derivatives in water by liquid chromatography-tandem mass spectrometry
    ZHAO Yunzhi, YANG Ping, QIAN Shu
    2015, 33 (5):  508-513.  DOI: 10.3724/SP.J.1123.2015.01005
    Abstract ( 611 )   [Full Text(HTML)] () PDF (944KB) ( 165 )  

    A new and fast method was developed for the simultaneous determination of 14 aniline derivatives (ADs) in water by direct injection-liquid chromatography-tandem mass spectrometry (LC-MS/MS) through optimizing chromatographic and mass spectrometric conditions. The water sample was filtered through a 0.45 μm polyether sulfone (PES) microfiltration membrane. The separation was performed on a Shim-pack FC-ODS column (75 mm×4.6 mm, 3 μm) with methanol-0.1%(v/v) formic acid aqueous solution (35:65, v/v) as mobile phases in gradient elution mode. The flow rate was 0.3 mL/min, and the column temperature was 35 ℃. The analytes were detected by LC-MS/MS in multiple reaction monitoring mode. Under the optimized conditions, the analysis of the 14 aniline derivatives was completed within 12 min and the calibration curves showed good linearity with correlation coefficients not less than 0.999. The detection limits of the 14 aniline derivatives ranged from 0.03 μg/L to 4.19 μg/L. The relative standard deviations of the 14 aniline derivatives in the spiked surface water at three levels (0.5, 5.0, 20.0 μg/L) were 0.4%-9.4% (n=6). The proposed method has the advantages of good anti-interference ability, rapidness and high sensitivity. It was successfully applied to the analysis of real samples, and the recoveries of the 14 aniline derivatives in the spiked real samples were 68.0%-130%.

    Analysis and assessment of four commercial products of Asian ginseng by ultra-performance liquid chromatography and chemometric analysis
    ZHANG Cuiying, CHEN Shilin, DONG Liang
    2015, 33 (5):  514-521.  DOI: 10.3724/SP.J.1123.2015.01018
    Abstract ( 586 )   [Full Text(HTML)] () PDF (931KB) ( 239 )  

    Ginseng Radix et Rhizoma (GRR, also named as white ginseng), Ginseng Radix et Rhizoma Rubra (GRR Rubra, also named as red ginseng), Ginseng Folium (GF) and Ginseng Rootlet (GR) products from Asian ginseng, one of the well-known Chinese traditional medicine for thousands of years, are now widely used around the world. Thus the comprehensive quality control is of paramount concern basing on the contents of the bioactive ginsenosides. A rapid, sensitive and reliable method of ultra-performance liquid chromatography coupled with a photodiode array detection (UPLC-PAD) was developed for the quantitative analysis of the 12 ginsenosides in the four commercial ginseng products of Asian ginseng. The chromatography was performed on an ACQUITY UPLCTM BEH C18 column using a gradient elution with acetonitrile/water as the mobile phases. Method validation including calibration curves, accuracies, precisions, repeatabilities and recoveries was investigated. The contents of the 12 ginsenosides were determined in 20 GRR, 4 GF, 4 GR and 11 GRR Rubra samples. To evaluate the sample quality, chemometric methods including hierarchical cluster analysis (HCA) and principal components analysis (PCA) were engaged in evaluating the GRR, GRR Rubra, GF and GR products from Asian ginseng. The results showed that HCA and PCA can be considered as the attractive chemometric techniques in situations where high sample throughput and multiple analytes are required.

    Comparison of the release behaviors of di(2-ethylhexyl) phthalate and tri(2-ethylhexyl) trimellitate from the polyvinyl-chloride infusion set into pharmaceutical solutions
    ZHANG Hong, YANG Fengmin, SHEN Gang, YANG Yueyang, TANG Yalin
    2015, 33 (5):  522-529.  DOI: 10.3724/SP.J.1123.2014.12029
    Abstract ( 685 )   [Full Text(HTML)] () PDF (852KB) ( 314 )  

    Polyvinyl-chloride (PVC) with plasticizers of di(2-ethylhexyl) phthalate (DEHP) and tris(2-ethylhexyl) trimellitate (TOTM) is widely used in medical and paramedical appliances. However, such plasticizers can leach from PVC products into contact solutions. The aim of this study is to investigate the release behaviors of DEHP and TOTM from the PVC intravenous infusion set into various pharmaceutical solutions under the simulated clinical conditions, such as the lipophilic substances (paclitaxel), parenteral nutrition (fat emulsion injection), acid and alkali pharmaceutical solution (levofloxacin hydrochloride injection, pH 3.0-5.0 and furosemide, pH 8.0-9.0). A simple and rapid high-performance liquid chromatographic method with UV detection (HPLC-UV) for the determination of DEHP or TOTM released from PVC medical devices into the above intravenous preparations was developed. The cumulative amounts of DEHP or TOTM released in 24 h were in the same following order: paclitaxel>fat emulsion injection>levofloxacin hydrochloride> furosemide solution. From a comparison of the cumulative amounts of released DEHP and TOTM from the above solutions, we found that the cumulative amount of TOTM is far less than that of DEHP, under the same conditions. The cumulative amount of the DEHP released in 24 h in the paclitaxel solution was 21.14 mg, while under the same conditions, the cumulative amount of TOTM was only 0.078 mg. The cumulative amount of DEHP is assumed to be about 270 times that of the released TOTM. Thus TOTM could be a superior alternative to DEHP for use in medical devices because of its potential lower leachability.

    A cell membrane chromatography method for investigation of 5-hydroxytryptamine receptor-ligustilide interaction
    DU Hui, ZHOU Na, LI Jingjing, FAN Fei
    2015, 33 (5):  530-534.  DOI: 10.3724/SP.J.1123.2015.01003
    Abstract ( 667 )   [Full Text(HTML)] () PDF (781KB) ( 175 )  

    A rat striatum cell membrane chromatography (CMC) frontal analysis method was developed for the determination of the equilibrium dissociation constants (KD) for 5-hydroxytryptamine (5-HT) receptor 5-HT1D-ligustilide interactions. Rat striatum was used for preparation of the cell membrane stationary phase (CMSP). An enzyme-linked immunosorbent assay (ELISA) was applied to determine the 5-HT level of CMSP before and after the adsorption of cell membrane, and the value was (40.5±2.3) pg per gram of silica. The CMC-offline-HPLC system was applied to specifically recognize the mixed standard solution of sumatriptan and ligustilide. Sumatriptan, a 5-HT1D agonist of 24.2 to 242 nmol/L, was pumped through a CMC column continuously, and the breakthrough curves were recorded. For further competitive studies, the mobile phase that contained ligustilide (37.0-370 nmol/L) was pumped through the column to saturate the binding sites. Afterwards, sumatriptan was propelled towards the column. The breakthrough curves were recorded and compared with those obtained from the column without saturation. KD values obtained using frontal analysis were 389 nmol/L and 4.21 μmol/L for sumatriptan and ligustilide, respectively. The competitive binding study indicated that the CMC method could be a quick and efficient way for determining the KD values in drug-receptor interactions.

    Deductive inference on the plate height equation of ultra performance liquid chromatography
    DAI Chaozheng
    2015, 33 (5):  535-540.  DOI: 10.3724/SP.J.1123.2014.10007
    Abstract ( 393 )   [Full Text(HTML)] () PDF (776KB) ( 167 )  

    In recent years, separation and analysis workers have made considerable progress on ultra performance liquid chromatography (UPLC). A lot of separation works have been completed which have never been done before. But the theory about chromatographic dynamics of UPLC from the beginning up to now, is remaining in 1950's. Some people explain the principle of UPLC by the van Deemter equation, but this is not right. In this paper, the dynamic process of UPLC has been studied. According to the chromatographic dynamics principle and starting from the heat conduction equation, the plate height equation of UPLC including the influence of mobile phase friction heat production has been deduced as follows: H=2γDm/u+((2λdpu1/3)/(u1/3+ω(Dm/dp)1/3))+((2ku)/((1+k)2(1+κ0)κd))+ ((θ(κ0+κ0k+k)2dp2u)/(Dmκ0(1+κ0)2(1+k)2)) +(κi(κ0+κ0k+k)2dp5/2u2/3)/(3κ0Ω Dm2/3(1+κ0)2(1+k)2+(r02(κ0κ0k+k)u)/(4(1+k)Dr)exp(-Kr02α). The last item on the right represents the contribution of mobile phase friction heat. When the linear velocity of mobile phase is lower, the contribution of mobile phase friction heat tending to become zero, the plate height equation is reduced to the Horvath and Lin equation. When the linear velocity of mobile phase is high, the temperature difference between the column axial center and edge is directly proportional to the mobile phase linear speed square, and the contribution of thermal effect will largely increased. In this paper, the author clearly pointed out that the column efficiency of UPLC has a direct bearing on the column diameter. Using fine diameter column is helpful to implement column efficiency. Too high mobile phase velocity will lead to the column efficiency collapsed.

    Determination of catechol in tobacco by high performance liquid chromatography-tandem mass spectrometry
    REN Zhiqin, AI Xiaoyong, HUANG Zhiqiang, ZHANG Yuan, WANG Zhi, ZHANG Feng
    2015, 33 (5):  541-544.  DOI: 10.3724/SP.J.1123.2015.01023
    Abstract ( 884 )   [Full Text(HTML)] () PDF (761KB) ( 268 )  

    An analytical method for the determination of catechol in tobacco by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been developed. A Sep-Park-C18 solid phase extraction cartridge was used for the enrichment of the analyte for HPLC-MS/MS analysis. The mobile phase was methanol-0.2% (v/v) formic acid with gradient elution. The sample was analyzed by HPLC-MS/MS in the ESI-scanning mode with multi-reaction monitoring (MRM) for qualitative and quantitative analyses. The linear range of calibration curve was 0.5-200 μg/kg with good correlation coefficients (r2=0.9989). The recoveries of catechol spiked in three levels were in the range of 83.1%-98.6%, with the relative standard deviations of 1.9%-5.8%. This method was initially applied to the research of catechol as a flavor additive in six retail tobacco samples and proved to be accurate, sensitive, convenient and practical. The analyte was found in the six retail tobacco samples, and in some cases, the presence of quite high concentrations of catechol in tobacco should be a matter of concern.

    Determination of 23 phthalate esters in scallion and other vegetables by solid-phase extraction coupled with gas chromatography-tandem mass spectrometry
    WANG Huifeng, DONG Xiaohai, JIA Bin, FENG Shuhui, LIU Jinxi, ZHONG Hongjian
    2015, 33 (5):  545-550.  DOI: 10.3724/SP.J.1123.2014.12031
    Abstract ( 789 )   [Full Text(HTML)] () PDF (805KB) ( 461 )  

    A method for the simultaneous determination of 23 phthalate esters in vegetables by solid-phase extraction coupled with gas chromatography-triple quadrupole mass spectrometry (SPE-GC-MS/MS) was developed and evaluated. The samples were extracted with acetonitrile, and cleaned-up with glass Florisil SPE columns, and diluted with n-hexane. The separation was performed on a DB-5MS UI capillary column (30 m×0.25 mm×0.25 μm) with temperature programming. The identification and quantification were performed by GC-MS/MS in selected reaction monitoring (SRM) mode. The external standard method was used. The processes of extraction and clean-up of scallion and other vegetables were investigated, and the chromatographic and MS parameters were optimized. The matrix effect was compensated by matrix spiked calibration. The extraction processes were investigated. The calibration curves of the phthalate esters showed good linearities in the ranges of 0.02-1 mg/L (0.1-5 mg/L for diisononyl phthalate (DINP) and diisodecyl-o-phthalate (DIDP)) with the correlation coefficients (r) over 0.99 except for bis(2-methoxyethyl) phthalate (DMEP). The limits of detection of phthalate esters in samples ranged from 0.01 to 0.05 mg/kg (S/N=3) and the limits of quantification ranged from 0.02 to 0.1 mg/kg (S/N=10). The average recoveries of the 23 analytes spiked in scallions ranged from 81.3% to 104.2% with the relative standard deviations (RSDs, n=6) of 3.2%-11.2%. The method is suitable for the determination of the 23 phthalate esters simultaneously in vegetables with easy operation, high accuracy and precision.