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Chinese Journal of Chromatography
2014, Vol. 32, No. 7
Online: 08 July 2014

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Recent Progresses in Multiphase Microfluidic Analysis and Capillary Electrophoresis FANG Qun 2014, 32 (7):  673-674.  DOI: 10.3724/SP.J.1123.2014.06030 Abstract ( 388 )   [Full Text(HTML)] () PDF (683KB) ( 225 )

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Hydrophilic interaction chromatography on silica column：retention mechanism and its influential factors LI Ruiping, YUAN Qin, HUANG Yingping 2014, 32 (7):  675-681.  DOI: 10.3724/SP.J.1123.2014.04048 Abstract ( 733 )   [Full Text(HTML)] () PDF (827KB) ( 410 )   Hydrophilic interaction chromatography (HILIC) is a valuable alternative to reversed phase liquid chromatography (RPLC) for the analysis of highly polar and hydrophilic compounds, in which the separation mechanism is quite different from RPLC and the separation selectivity is complementary to RPLC. This separation mode can be characterized as normal phase liquid chromatography (NPLC) on polar columns in aqueous-organic mobile phases rich in organic solvents (usually acetonitrile). Silica has been the earliest developed and most widely used HILIC stationary phase. This review deals with the recent advances in the development of the retention mechanism on silica column with special attention to the effects of stationary phase, mobile phase composition and temperature on separation in HILIC mode. Moreover, the developing trends and applications of this HILIC mode are presented.

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Simultaneous analysis of global DNA methylation and hydroxymethylation in tissues by liquid chromatography-tandem mass spectrometry MU Xiaoli, ZHANG Jie, PENG Siyuan, WANG Xiaoxue, SHEN Heqing 2014, 32 (7):  682-686.  DOI: 10.3724/SP.J.1123.2014.03025 Abstract ( 648 )   [Full Text(HTML)] () PDF (831KB) ( 437 )   Measuring global DNA methylation and hydroxymethylation is important in researches of effect and mechanism of environmental pollutants exposure. A method based on liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) was developed to simultaneously determine global DNA methylation and hydroxymethylation level in biological tissues. DNA was extracted from tissues and converted into single nucleotide via enzyme digestion. Liquid chromatography coupled to tandem mass spectrometry was used to measure the concentrations of 5-methylcytidine, 5-hydroxymethylcytosine and deoxyguanosine, which were used to calculate global DNA methylation ratios and hydroxymethylation ratios. The results showed that the correlation coefficients were higher than 0. 99. The limit of detection (LOD, S/N=3) and the limit of quantification (LOQ, S/N=10) of 5-methylcytidine were 0.015 and 0.045 ng/mL, respectively. They reached 0.001 and 0.003 ng/mL for 5-hydroxymethylcytosine, and were 0.2 and 0.6 ng/mL for deoxyguanosine. The developed method was further successfully applied to investigate global DNA methylation and hydroxymethylation alteration in liver and cerebellum of rats exposed to arsenic via drinking water. This approach could quantitatively detect 5-methylcytidine, 5-hydroxymethylcytosine and deoxyguanosine with high sensitivity, repeatability and stability. Our study provided a means to simultaneously analyze global DNA methylation and hydroxymethylation.

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Rapid screening and confirmation of antidepressants in blood using automated solid phase extraction and liquid chromatography-time-of-flight mass spectrometry SHI Yintao, GUO Jingqi, WANG Huijun, DUAN Jie, YU Hongjiang, ZHENG Jing, WANG Junwei 2014, 32 (7):  687-692.  DOI: 10.3724/SP.J.1123.2014.04013 Abstract ( 617 )   [Full Text(HTML)] () PDF (1029KB) ( 261 )   A high-throughput method was developed for screening antidepressants in blood by automated solid phase extraction and liquid chromatography with high resolution quadrupole-time-of-flight mass spectrometry (ASPE-LC-Q-TOF/MS). The samples were cleaned up by an HLB solid phase extraction cartridge and analyzed by LC-Q-TOF/MS under electrospray ionization (ESI) mode with scanning range of m/z 50-1000 Da. The chromatographic separation was performed on an Agilent Eclipse Plus C18 column (50 mm×2.1 mm, 1.8 μm) with gradient elution using methanol and 5 mmol/L ammonium formate aqueous solution (containing 0.2% formic acid) as mobile phases. Rapid screening and confirmation can be achieved using MS matching scores, deviation of retention time, measured mass, isotopic abundance matching scores, isotope space matching scores and MS/MS matching scores. The quantitative analysis was carried out by correlating the extracting peak area with accurate mass. Good linearities were observed in the range of 1-500 μg/L with the correlation coefficients from 0.9976 to 0.9997. The limits of detection were 0.01-0.5 μg/L. The spiked recoveries were 79.6%-96.4% with the relative standard deviations of 4.1%-6.4%. The result screening database was built using Agilent MassHunter PCDL Manager software and then used for the analysis of spiked samples. MS matching scores, isotopic abundance matching scores, isotope space matching scores (all > 95 points) and MS/MS matching scores (> 70 points) were applied to identify the analytes. The results showed that all the spiked antidepressants could be correctly identified with low deviation of retention time (< 0.1 min) and mass (< 1 mDa). The developed method was further applied for the analysis of poisoning cases, and amitriptyline, carbamazepine, doxepin were detected. In brief, the method is rapid, sensitive, simple, reliable, and suitable for the screening and confirmation of antidepressants in forensic and clinical analytical toxicology.

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Rapid simultaneous determination of 53 β-lactam antibiotics and their metabolites in milk by ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry ZHANG Xiuyao, CAI Xinxin 2014, 32 (7):  693-701.  DOI: 10.3724/SP.J.1123.2014.03019 Abstract ( 732 )   [Full Text(HTML)] () PDF (865KB) ( 423 )   A rapid method for the determination of 53 β-lactams and their metabolites residues in milk was developed by ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS). The method was based on protein precipitation by adding equal quantity of acetonitrile, followed by the ultra filtration of the extracts. The analysis of the residues was achieved on an ACQUITY BEH C18 column with gradient elution using mobile phases of 0.1% formic acid in water and acetonitrile. The analytes were detected by positive electrospray ionization tandem mass spectrometry in the multiple reaction monitoring (MRM) mode, and quantified by matrix-matched internal standard calibration. The cycle time of each analysis was 10 min. Under the optimum operation conditions, excellent linear dynamic range was observed from the quantification limits to 200 μg/kg with the correlation coefficients better than 0.9911 for all the compounds. The average recoveries for all the β-lactams and their metabolites ranged from 71% to 121% with the relative standard deviations of 1.7%-19% (n=6). This method enabled the screening for more than 50 samples per day by one person and also showed good performance for quantitation, and allowed the determination of the β-lactams and their metabolites residues in milk below the maximum residue levels (MRLs) according to the Bulletin No. 235 (2002) of Ministry of Agriculture, P. R. China and EU Regulation 2377/90/EC (2008 Revised).

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Simultaneous determination of twenty psychoactive drugs in pork by solid phase extraction coupled with ultra performance liquid chromatography-tandem mass spectrometry SUN Ting, WANG Luxiao, ZENG Sanmei, WU Min, YAN Lijuan, ZHANG Feng, HUANG Zhiqiang 2014, 32 (7):  702-706.  DOI: 10.3724/SP.J.1123.2014.03002 Abstract ( 1369 )   [Full Text(HTML)] () PDF (861KB) ( 427 )   A method for the simultaneous determination of 20 psychoactive drugs in pork by solid phase extraction coupled with ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) was established. The samples were extracted with alkalified acetonitrile, and then cleaned up using solid phase extraction with an Oasis MCX column. The UPLC separation was performed on a C18 column (50 mm×2.1 mm, 1.7 μm) using a gradient elution with the mobile phases of 0.1% (v/v) formic acid in water and acetonitrile. The ESI-MS/MS detection was achieved in positive mode under multiple reaction monitoring (MRM) mode. The calibration curves showed good linearity in the range of 5-100 μg/L with the correlation coefficients more than 0.99 for the 20 psychoactive drugs. The limits of quantification (LOQ, S/N≥10) for the 20 psychoactive drugs were 5 μg/kg. The average recoveries of the 20 psychoactive drugs spiked in blank pork at three levels of 5, 10 and 50 μg/kg were 66.8%-97.2% with the relative standard deviations from 4.2% to 12.4%. The method is suitable for the simultaneous determination of the 20 psychoactive drugs in pork with the characteristics of easy operation, high accuracy and precision.

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Determination of 21 plant growth regulator residues in fruits by QuEChERS-high performance liquid chromatography-tandem mass spectrometry HUANG Hehe, ZHANG Jin, XU Dunming, ZHOU Yu, LUO Jia, LV Meiling, CHEN Shubin, WANG Lianzhu 2014, 32 (7):  707-716.  DOI: 10.3724/SP.J.1123.2014.03003 Abstract ( 1209 )   [Full Text(HTML)] () PDF (3539KB) ( 783 )   A method for the simultaneous detection of 21 plant growth regulators in fruits by QuEChERS-high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The samples were initially extracted with acetonitrile containing 1%(v/v) acetic acid, followed by clean-up using the powder of magnesium sulfate and C18. The resulting samples were separated on a C18 column, and detected under positive and negative multiple reactions monitoring (MRM) mode through polarity switching between time segments. The matrix-matched external standard calibration curves were used for quantitative analysis. The linearities of chlormequat chloride, mepiquat chloride, choline chloride, cyclanilide, forchlorfenuron, thidiazuron, inabenfide, paclobutrazol, uniconazole and triapenthenol were in the concentration range of 0.1-500 μg/L, daminozide and 6-benzylaminopurine in the concentration range of 1.0-500 μg/L, 2,3,5-triiodobenzoic acid, 2,4-D, cloprop, 4-chlorophenoxyacetic acid (4-CPA) and trinexapac-ethyl in the concentration range of 2.0-1000 μg/L, abscisic acid (ABA), gibberellic acid (GA3), 1-naphthaleneacetic acid (NAA) and indol-3-ylacetic acid (IAA) in the concentration range of 10-1000 μg/L, with the correlation coefficients higher than 0.990. The limits of detection and the limits of quantification of the method were 0.020-6.0 μg/kg and 0.10-15.0 μg/kg, respectively. For all the samples, the average spiked recoveries ranged from 73.0% to 111.0%, and the relative standard deviations (RSDs, n=6) were in the range of 3.0%-17.2%. The method is quick, easy, effective, sensitive and accurate, and can meet the requirements for the determination of the 21 plant growth regulator residues in fruits.

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Determination of five arsenic species in rice by liquid chromatography-inductively coupled plasma-mass spectrometry GONG Jiadi, CAO Xiaolin, CAO Zhaoyun, BIAN Yingfang, YU Shasha, CHEN Mingxue 2014, 32 (7):  717-722.  DOI: 10.3724/SP.J.1123.2014.03015 Abstract ( 625 )   [Full Text(HTML)] () PDF (1053KB) ( 267 )   A method was developed for the simultaneous determination of arsenic acid [As (Ⅴ)], arsenious acid [As (Ⅲ)], arsenobetaine (AsB), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in rice by liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS). The extraction reagent was 0.3 mol/L nitric acid with heat-assistant condition for 1.5 h at 95 ℃. Then, the five arsenic species were separated by an anion exchange column (Dionex IonPac AS19, 250 mm×4 mm) and detected by ICP-MS. Four kinds of extracted solutions were compared through the extraction efficiency. The concentration of nitric acid, the temperature and the extraction time were optimized. The recoveries of the five arsenic species spiked in rice at two levels ranged from 89.6% to 99.5% with the relative standard deviations (RSDs, n=5) of 0.6%-3.6%. The measured values of the arsenic species in standard rice materials were consistent with their standard values. The linear ranges were 0.05-200 μg/L for AsB and DMA, 0.10-400 μg/L for As (Ⅲ) and MMA, 0.15-600 μg/L for As (V). The limits of detection for the five arsenic species were 0.15-0.45 μg/kg. The results showed that the method is much more precise for the risk assessment of the rice. This method is simple, accurate and durable for the determination of arsenic species in rice.

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Simultaneous determination of six perfluorinated organic compounds in feed by using polyamide solid-phase extraction with ultra performance liquid chromatography-tandem mass spectrometry LIN Qin, FU Fengfu, CHEN Guonan, ZHENG Xiaoyan, DAI Ming 2014, 32 (7):  723-729.  DOI: 10.3724/SP.J.1123.2014.03023 Abstract ( 642 )   [Full Text(HTML)] () PDF (1535KB) ( 419 )   A method for the determination of six perfluorinated organic compounds (PFCs) in feed has been developed. It is based on polyamide solid-phase extraction (SPE) together with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample was extracted by acidified acetonitrile. The extraction solution was enriched by a polyamide SPE cartridge under acidic condition, and cleaned-up using methanol, eluted by 5%(v/v) ammonia/methanol solvent and determined by UPLC-MS/MS. The UPLC separation was carried out on an Acquity BEH C18 column (100 mm×2.1 mm, 1.7 μm). The mobile phases were 5 mmol/L ammonium acetate and acetonitrile with a gradient elution. Under the optimal conditions, the PFCs were analyzed under multiple reaction monitoring (MRM) mode with negative electrospray ionization. The isotope internal standard method was used to determine the six PFCs, and improve the quantitative accuracy. All of the target compounds exhibited good linearity (r>0.995) over a concentration range of 0.5-25 μg/L. The detection limits of the six PFCs were all smaller than 0.1 μg/kg. The mean recoveries of the six PFCs were in the range of 94.2% to 108.9% with the relative standard deviations (RSDs) of 1.8%-8.6% (n=6). The method for the determination of PFCs in feed is low-cost, favorable effect and suitable for the detection of complex matrix samples.

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Determination of eight bisphenol diglycidyl ethers in water by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry ZHANG Haijing, LIN Shaobin 2014, 32 (7):  730-734.  DOI: 10.3724/SP.J.1123.2014.02026 Abstract ( 656 )   [Full Text(HTML)] () PDF (805KB) ( 384 )   A solid phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) method was developed for the determination of eight bisphenol diglycidyl ethers, including bisphenol A diglycidyl ether (BADGE), bisphenol A (3-chloro-2-hydroxypropyl) glycidyl ether(BADGE·5HCl), bisphenol A bis(3-chloro-2-hydroxypropyl) ether(BADGE·52HCl), bisphenol A (2,3-dihydroxypropyl) glycidyl ether(BADGE·5H2O), bisphenol A bis(2,3-dihydroxypropyl) ether(BADGE·52H2O), bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) ether(BADGE·5HCl·5H2O), bisphenol F diglycidyl ether(BFDGE) and bisphenol F bis(3-chloro-2-hydroxypropyl) ether(BFDGE·52HCl) in water. A total of ten samples were collected from the leaching of the coatings for drinking water supply system. Then, 200 mL exposure water was preconcentrated on C18 solid-phase extraction cartridge. The eight compounds were analyzed by liquid chromatography-tandem mass spectrometry method on a C18 column by the gradient elution with methanol, water and 5 mmol/L ammonium acetate as mobile phases in the multiple reaction monitoring (MRM) scan mode. The external matrix standard solutions were used for the quantitative determination and the calibration curves of the eight compounds showed good linearity in the range of 0.007-5.00 μg/L with the correlation coefficients more than 0.9990. The limits of quantification (LOQs) of the method were 7-91 ng/L. The spiked recoveries ranged from 79.1% to 101% with the relative standard deviations of 4.0%-12%. The method is sensitive and accurate, and is applicable to the determination of bisphenol diglycidyl ethers in water.

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Determination of six phthalate acid esters in camellia oil by gas chromatography-mass spectrometry coupled with solid-phase extraction using single-walled carbon nanotubes as adsorbent ZHANG Fan, LI Zhonghai, ZHANG Ying, HUANG Zhiqiang, WANG Xiaosong 2014, 32 (7):  735-740.  DOI: 10.3724/SP.J.1123.2014.04036 Abstract ( 830 )   [Full Text(HTML)] () PDF (1100KB) ( 316 )   An analytical method based on solid-phase extraction with single-walled carbon nanotubes (SWCNTs) as adsorbent was developed for the simultaneous determination of six phthalate acid esters (PAEs) in camellia oil by gas chromatography-mass spectrometry (GC-MS). The samples were diluted by hexane and then cleaned up with a glass SWCNTs solid phase extraction (SPE) column. The PAEs were measured by GC-MS in selected ion monitoring (SIM) mode, using external standard method for quantitative analysis. The important factors affecting extraction efficiency, such as the dilution volume of hexane, the type of adsorbent material, the dosage of SWCNTs, the volume of wash solution, the type and volume of elution solution were optimized. The optimal conditions were as follows: the dilution volume of hexane was 5 mL, the dosage of SWCNTs was 0.6 g, the wash solution was 20 mL hexane, and the elution solution was 5 mL toluene. The six PAEs had a good linear range from 0.05 mg/L to 1.0 mg/L, with the correlation coefficients (r) all above 0.9999. The average recoveries of the six targets in spiked camellia oil (from 0.05 mg/kg to 1.0 mg/kg) ranged from 86.4% to 111.7% with the relative standard deviations (RSDs) from 4.2% to 10.4%. The developed method is accurate, quick and suitable for the determination of the six PAEs in camellia oil.

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Determination of four insecticide residues in honey and royal jelly by gas chromatography-negative chemical ionization mass spectrometry XIA Guanghui, SHEN Weijian, YU Keyao, WU Bin, ZHANG Rui, SHEN Chongyu, ZHAO Zengyun, BIAN Xiaohong, XU Jiyang 2014, 32 (7):  741-745.  DOI: 10.3724/SP.J.1123.2014.01043 Abstract ( 752 )   [Full Text(HTML)] () PDF (799KB) ( 217 )   A method was developed for the determination of four insecticide residues in honey and royal jelly by gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The honey and royal jelly samples were treated with different preparation methods as the result of the different components. The honey sample was extracted with ethyl acetate and cleaned up with primary second amine, and the royal jelly sample was extracted with acetonitrile-water (1:1, v/v), and cleaned up with a C18 solid-phase extraction column. Finally, the extracts of the honey and royal jelly were analyzed by GC-NCI/MS in selected ion monitoring (SIM) mode separately. External standard calibration method was used for quantification. The linearities of calibration curves of the four insecticides were good with the correlation coefficients greater than 0.99 in the range of 50-500 μg/L. The limits of the detection (LODs) of the four insecticides were in the range of 0.12-5.0 μg/kg, and the limits of the quantification (LOQs) were in the range of 0.40-16.5 μg/kg. The recoveries of the four insecticides spiked in honey and royal jelly at three spiked levels (10, 15 and 20 μg/kg) were in the range of 78.2%-110.0%, and the relative standard deviations (RSDs) were all below 14%. The sensitivity and selectivity of this method were good with no interfering peaks. The proposed method is simple, quick and effective to analyze the four insecticide residues in honey and royal jelly.

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Determination of thermodynamic properties of poly(cyclohexyl methacrylate) by inverse gas chromatography Ismet KAYA, Cigdem Yigit PALA 2014, 32 (7):  746-752.  DOI: 10.3724/SP.J.1123.2014.04028 Abstract ( 694 )   [Full Text(HTML)] () PDF (669KB) ( 328 )   In this work, some thermodynamic properties of poly(cyclohexyl methacrylate) were studied by inverse gas chromatography (IGC). For this purpose, the polymeric substance was coated on Chromosorb W and which was filled into a glass column. The retention times (tr) of the probes were determined from the interactions of poly(cyclohexyl methacrylate) with n-pentane, n-hexane, n-heptane, n-octane, n-decane, methanol, ethanol, 2-propanol, butanol, acetone, ethyl methyl ketone, benzene, toluene and o-xylene by IGC technique. Then, the specific volume (Vg0) was determined for each probe molecule. By using (1/T; lnVg0) graphics, the glass transition temperature of poly(cyclohexyl methacrylate) was found to be 373 K. The adsorption heat under the glass transition temperature (ΔHa), and partial molar heat of sorption above the glass transition (ΔH1S), partial molar free energy of sorption (ΔG1S) and partial molar entropy of sorption (ΔS1S) belonging to sorption for every probe were calculated. The partial molar heat of mixing at infinite dilution (ΔH1∞), partial molar free energy of mixing at infinite dilution (ΔG1∞), Flory-Huggins interaction parameter (χ12∞) and weight fraction activity coefficient (a1/w1)∞ values of polymer-solute systems were calculated at different column temperatures. The solubility parameters (δ2) of the polymer were obtained by IGC technique.

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Synthesis of two metal-organic complexes and characterization of their adsorption behaviour of ten polycyclic aromatic hydrocarbons MENG Jie, SUN Yuxiu, LI Yan 2014, 32 (7):  753-761.  DOI: 10.3724/SP.J.1123.2014.03014 Abstract ( 652 )   [Full Text(HTML)] () PDF (3723KB) ( 203 )   Metal-organic frameworks (MOFs) are concerned mainly due to the unusual properties for diverse analytical applications, such as high surface area, good thermal stability, in-pore functionality and outer-surface modification. Two metal-organic complexes were prepared by two methods of hydrothermal synthesis and room temperature synthesis, separately. The compositions, structures, thermal stability and adsorption properties of the two complexes were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) method, which indicated that the two complexes have not only good thermal stability but also good adsorption for polycyclic aromatic hydrocarbons (PAHs). PAHs enter into environment leading to pollution by industrial and agricultural production and life, rooting in the incomplete combustion or pyrolysis of organism. PAHs are strongly carcinogenic and mutagenic. Some PAHs are considered as endocrine disruptors, and maybe have biological effects on human health. Regulations have thus been formulated for monitoring and controlling PAHs by the United States Environmental Protection Agency (U. S. EPA) and other government agencies. Adsorption kinetic of PAHs on the two complexes could be well described by the pseudo-second order kinetic model, and the adsorption behaviors of the two complexes on PAHs are in accord with Langmuir model. In addition, the adsorption capacities increase with the increasing adsorbent dosage. It is proved by the FT-IR data that π-π interactions between the PAHs and the framework terephthalic acid molecules. Ten PAHs were adsorbed well on the two complexes which have good adsorptive selectivity. By further optimizing of the two complex materials, it is promising to use them as chromatographic stationary phases.

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Simultaneous determination of five triterpenoid saponins in different parts of Aralia elata by high performance liquid chromatography-tandem mass spectrometry MA Hui, SONG Shaojiang, LIU Feifei, ZHANG Yan, PENG Ying 2014, 32 (7):  762-766.  DOI: 10.3724/SP.J.1123.2014.03009 Abstract ( 662 )   [Full Text(HTML)] () PDF (830KB) ( 289 )   A method was developed for the simultaneous determination of congmunoside Ⅱ, congmunoside Ⅳ, congmunoside Ⅴ, congmunoside Ⅹ and congmuyenoside Ⅱ in different parts of Aralia elata by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The chromatographic separation was performed on an Alltima C18 analytical column (250 mm×4.6 mm, 5 μm) using the mobile phases of acetonitrile and 0.1% (v/v) formic acid aqueous solution with gradient elution. The separated compounds were detected in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI+). The linear ranges of congmunoside Ⅱ, congmunoside Ⅳ, congmunoside Ⅴ, congmunoside Ⅹ and congmuyenoside Ⅱ were 0.17-108 μg/L, 0.53-329 μg/L, 0.77-480 μg/L, 0.77-480 μg/L and 0.82-510 μg/L, respectively. The extraction recoveries varied from 99.0% to 100.2%. The developed method is rapid, accurate and reproducible, and is successfully utilized as a quality control method for Aralia elata. The results indicate that the order of contents of these five saponins in different parts of Aralia elata is root bark >leaves >seeds >buds.

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Preparation of triterpene saponins from Platycodon grandiflorum by two-dimensional hydrophilic interaction liquid chromatography-reversed phase liquid chromatography XING Qianqian, FU Qing, JIN Yu, LIANG Xinmiao 2014, 32 (7):  767-772.  DOI: 10.3724/SP.J.1123.2014.03027 Abstract ( 724 )   [Full Text(HTML)] () PDF (846KB) ( 231 )   A two-dimensional (2-D) preparative liquid chromatography method was developed for the preparation of triterpene saponins from Platycodon grandiflorum using hydrophilic interaction liquid chromatography (HILIC) coupled with reversed phase liquid chromatography (RPLC). At first, the crude extract was obtained from Platycodon grandiflorum by boiled alcohol precipitation. Then, the concentrated crude extracts were continuously pretreated using solid phase extraction (SPE) under reversed-phase and hydrophilic-phase modes to remove the impurities. Subsequently, XAmide column (150 mm×20 mm, 5 μm) was selected to separate the triterpene saponin constituents under HILIC mode using water and acetonitrile as mobile phases. From 6 min to 25 min, each fraction was collected per minute under time-triggered mode and 20 fractions were collected. The 18th fraction (JG23) was selected for further purification. The column of Atlantis PrepT3 (100 mm×30 mm, 5 μm) was chosen and two monomeric compounds were obtained. The two compounds with over 90% purity were identified as deapi-platycoside E and platycoside E with mass spectrometry (MS) and nuclear magnetic resonance (NMR). This 2-D HILIC-RPLC method with high orthogonality can be used in the preparation of triterpene saponins from natural products.

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Determination of piperidinium ionic liquid cations by ion-pair chromatography-indirect ultraviolet detection WANG Miaoyu, YU Hong, LI Ping, LI Jie, GAO Yufeng 2014, 32 (7):  773-778.  DOI: 10.3724/SP.J.1123.2014.03036 Abstract ( 758 )   [Full Text(HTML)] () PDF (823KB) ( 344 )   A method was developed for the determination of piperidinium cations by ion-pair chromatography with indirect ultraviolet detection. Chromatographic separation was performed on a reversed-phase C18 column using background ultraviolet absorption reagent-ion-pair reagent/organic solvent as mobile phase. The effects of the background ultraviolet absorption reagent, detection wavelength, ion-pair reagent, organic solvent, column temperature and flow rate on the determination of piperidinium cations were investigated and the retention rules were studied. The optimized chromatographic conditions for the determination of piperidinium cations were as follows: mobile phase, 0.5 mmol/L 4-aminophenol hydrochloride-0.1 mmol/L 1-heptanesulfonic acid sodium aqueous solution/methanol (80:20, v/v); detection wavelength, 210 nm; column temperature, 30 ℃; flow rate, 1.0 mL/min. Under these conditions, the three piperidinium cations were baseline separated within 4 min. The detection limits (S/N=3) of the piperidinium cations were 0.137-0.545 mg/L. The relative standard deviations (n=5) for peak area and retention time were 0.72% and 0.37% respectively. The method has been successfully applied to the determination of piperidinium cations in ionic liquids synthesized by chemistry laboratory. The recoveries of piperidinium cations after spiking were 97.0%-98.4%. The method is simple, rapid, reproducible, linear, and can meet the quantitative analysis requirement for the determination of piperidinium cations.

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Determination of endogenous agmatine in rat plasma by isotope dilution-gas chromatography-mass spectrometry QIU Zhongli, LIN Ying, XIONG Zhili, XIE Jianwei 2014, 32 (7):  779-783.  DOI: 10.3724/SP.J.1123.2014.03030 Abstract ( 629 )   [Full Text(HTML)] () PDF (816KB) ( 310 )   A method for the determination of endogenous agmatine in rat plasma was developed by isotope dilution-gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The plasma samples were analyzed after protein precipitation, evaporation, derivatization by hexafluoroacetone (HFAA), and clean-up on a Florisil SPE column. The GC-MS analysis utilized stable isotope d8-agmatine as internal standard. The samples after treatment were tested by negative chemical ionization with selected ion monitoring (SIM) which was set at m/z 492 (molecular ion of agmatine) and m/z 500 (molecular ion of internal standard). The limit of detection (LOD) of agmatine standard solution was 0.0057 ng/mL. The calibration curve of the agmatine spiked in rat plasma showed a good linear relationship at the range of 1.14-57.0 ng/mL (r=0.997). The recoveries of agmatine spiked in rat plasma ranged from 92.3% to 109.8%. Inter-day and intra-day precisions were less than 15%. The average concentration level of agmatine in rat plasma was (22±9) ng/mL, and there was no significant difference between male and female SD rats (p>0.05). The method is high sensitive and specific, and can be used for the determination of endogenous agmatine in plasma. It provides a strong support for the subsequent research of agmatine.

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Simultaneous determination of 16 organophosphorous pesticides in vegetables, fruits and tea by gas chromatography coupled with clean-up by mesoporous alumina as solid-phase extraction adsorbent HU Yeqin, XI Cunxian, CAO Shurui, WANG Guomin, LI Xianliang, ZHANG Lei, ZHANG Yunhuai 2014, 32 (7):  784-788.  DOI: 10.3724/SP.J.1123.2014.03034 Abstract ( 699 )   [Full Text(HTML)] () PDF (3109KB) ( 368 )   A gas chromatographic method based on solid-phase extraction was developed for the simultaneous determination of 16 organophosphorous pesticides in vegetables, fruits and tea, including cabbage, lettuce, pumpkin, onion, tomato, turnip, apple, pear and tea. The samples were extracted with ethyl acetate, and clean-up with mesoporous alumina as solid-phase extraction adsorbent. The separation of target compounds was performed on a DB-1701 capillary column, and the quantitative analysis of the organophosphorous pesticides was carried out by gas chromatography with flame photometric detection. The results showed that the calibration curves of the 16 organophosphorous pesticides were linear in the range of 10-2000 μg/L with good correlation coefficients (R2>0.997). The recoveries of the pesticides in different samples at three spiked levels ranged from 83.2% to 103.8% with the relative standard deviations of 2.0%-9.9%. This method has high sensitivity, high accuracy and good repeatability, and can be applied to the determination of the organophosphorus pesticide residues in vegetables, fruits and tea.