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Chinese Journal of Chromatography
2016, Vol. 34, No. 5
Online: 08 May 2016

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Recent advances in the methods and applications used to analyze eicosanoids YANG Chan, MAI Danti, PAN Zhemin, XUE Yun, WANG Yan, YAN Chao 2016, 34 (5):  449-455.  DOI: 10.3724/SP.J.1123.2016.01004 Abstract ( 565 )   [Full Text(HTML)] () PDF (1119KB) ( 95 )   Eicosanoids are a large family derived from polyunsaturated fatty acids, including prostaglandins, thromboxanes and leukotrienes. They are biologically active lipid mediators and are known to play an important role in numerous physiological and pathophysiological processes, such as inflammation. This complete enzymatic system produces hundreds of eicosanoids derived from arachidonic acids and related polyunsaturated fatty acids with very similar structures, chemistries and physical properties which makes the analysis of eicosanoids a challenging task, especially in biological samples. In this article, we review and discuss the methods and applications published over the last five years that have been used to analyze eicosanoids in biological samples, and emphasize the recent advances and the latest developments.

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Preparation of poly(guanidinium ionic liquid)s materials and evaluation of their recognition properties for protein GUO Yanling, GU Yuchen, DENG Qiliang 2016, 34 (5):  456-460.  DOI: 10.3724/SP.J.1123.2016.02001 Abstract ( 356 )   [Full Text(HTML)] () PDF (1735KB) ( 72 )   Protein phosphorylation is one of the most important post-translational modifications in life activities, which has a close relationship to the precise regulation of life activities. Thus, preparation of materials capable of selective enrichment of phosphoproteins is significantly important to phosphoproteome research. In this research, we prepared poly(guanidinium ionic liquid)s materials by using a synthesized guanidinium ionic liquid functional monomer. Poly(guanidinium ionic liquid)s materials were characterized by Fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM) and thermo gravimetric analyzer (TGA). The results indicated that microspheres had a mean size of 200 nm in diameter. Using β-casein as a model phosphoprotein, the recognition properties of the obtained materials for phosphoprotein were evaluated. The adsorption results showed that microspheres not only had a high adsorption capacity for phosphorylation proteins (599.1 mg/g for β-casein) and a rapid balance in 1 h, but also displayed high selectivity to phosphorylation proteins.

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Performance evaluation of 1.2 μ m fibrous core-shell packing material for pressurized capillary electrochromatography SHI Wenjun, TIAN Huajun, XUE Yun, WENG Zhongya, QU Qishu, WANG Yan, YAN Chao 2016, 34 (5):  461-466.  DOI: 10.3724/SP.J.1123.2015.12039 Abstract ( 407 )   [Full Text(HTML)] () PDF (1167KB) ( 60 )   Silica microsphere packing material with fibrous shells (1.2 μ m) was successfully synthesized and bonded with octadecylsilane functionality. These stationary phase particles were packed into fused-silica capillary with 100 μ m i.d. for a total length of 350 mm (70 mm effective length), which was evaluated for pressurized capillary electrochromatography (pCEC). The efficiency of the C18 reversed-phase column was characterized through the theoretical plates of thiourea and naphthalene. The effects of experimental parameters such as the content of acetonitrile in the mobile phase, the concentration of the buffer solution, the pH value of the mobile phase, the flow rate, the applied voltage and the on-column efficiency were investigated. The results showed a typical reversed-phase chromatographic performance. The eight neutral compounds were baseline separated within 8 min and the column efficiency as high as 190792 plate/m for benzophenone was obtained with the optimal conditions of 10 mmol/L phosphate buffer (pH 7.2) in 70% (v/v) acetonitrile aqueous solution at an applied negative voltage of 10 kV and a supplementary pressure of 1.66×107 Pa. The optimal linear velocity was 1 mm/s. The research work confirmed the feasibility of using 1.2 μ m silica microsphere packing material with fibrous shells as a novel stationary phase for pCEC.

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Preparation of a new organic-silica hybrid monolithic column and its applications in capillary liquid chromatography and pressurized capillary electrochromatography WENG Zhongya, XUE Yun, SHI Wenjun, WANG Yan, YAN Chao 2016, 34 (5):  467-472.  DOI: 10.3724/SP.J.1123.2015.12040 Abstract ( 450 )   [Full Text(HTML)] () PDF (2529KB) ( 105 )   The organic-silica hybrid poly(POSS-co-AM) monolithic columns were prepared by in-situ polymerization process with octavinyl-T8-silsesquioxane (POSS) as a crosslinking agent and acrylamide (AM) as monomer, tetrahydrofuran (THF) as a porogenic agent and azobisisobutyronitrile (AIBN) as initiator. In order to optimize the properties, the composition of the polymerization mixture was investigated. The optimum preparation conditions were as follows: both the mass ratios of monomer to porogen and POSS to AM were 1.0: 5.0; the mass fraction of the initiator (AIBN) was 0.1%. With the help of POSS materials, homogeneous column bed and good permeability were obtained. The columns were used in capillary liquid chromatography (cLC) and pressurized capillary electrochromatography (pCEC) for the separation of mixtures of amines, nucleosides, nitrobenzene amines. Satisfactory separations for these samples are achieved. The column is proved to be useful in both reversed-phase chromatography (RPLC) and hydrophilic interaction chromatography (HILIC).

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Simultaneous determination of 18 phenol pollutants in waste water by high performance liquid chromatography- tandem mass spectrometry LUO Birong, WAN Xu, DENG Xingliang, YU Yuanyuan, XIE Zhenwei 2016, 34 (5):  473-480.  DOI: 10.3724/SP.J.1123.2016.02018 Abstract ( 422 )   [Full Text(HTML)] () PDF (985KB) ( 83 )   A method was developed for the simultaneous determination of 18 phenol pollutants in waste water by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). A volume of 5.0 mL waste water was placed into a centrifuge tube. Ammonia was added to the waste water to adjust pH≥12. A volume of 1.0 mL methylene chloride-hexane solution (2: 1, v/v) was added to the waste water, then the centrifuge tube was oscillated for 5 min and centrifuged for 5 min at 4000 r/min. The water sample was filtered through a 0.22 μ m polytetrafluoroethylene (PTFE) microfiltration membrane and adjusted to neutral by formic acid. With methanol-0.01 mol/L ammonium formate/formic acid aqueous solution (pH 4.0) as mobile phase, the separation was performed on a Thermo Hypersil ODS column (100 mm×2.1 mm, 5.0 μ m) in gradient elution. The flow rate was 0.2 mL/min. The column temperature was 30℃. The samples were detected by multiple reaction monitoring (MRM) mode with negative electrospray ionization. The phenol pollutants were quantified by external standard method. The calibration curves of the phenol pollutants showed good linearities in a suitable range with correlation coefficients (r2) not less than 0.9991. The detection limits of phenol pollutants ranged from 0.10 μ g/L to 0.88 μ g/L. The relative standard deviations of phenol pollutants were 2.5%-9.9% (n=6). The average recoveries of the 18 phenol pollutants spiked in waste water samples ranged from 68.7% to 118%(n=3). The method has been proven to be sensitive, rapid and little interference. It is suitable for the determination of the 18 phenol pollutants simultaneously in environmental waste water.

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Simultaneous determination of 26 β-agonists in pork by dispersive solid-phase extraction and isotope dilution-high performance liquid chromatography-tandem mass spectrometry LUO Huitai, HUANG Xiaolan, WU Huiqin, ZHU Zhixin, HUANG Fang, LIN Xiaoshan, ZHANG Qiuyan, MA Yefen 2016, 34 (5):  481-489.  DOI: 10.3724/SP.J.1123.2016.01015 Abstract ( 408 )   [Full Text(HTML)] () PDF (926KB) ( 123 )   A method has been developed and validated for the determination of 26 β-agonists in pork using dispersive solid-phase extraction (dSPE) coupled with isotope dilution-high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). After the samples were hydrolyzed by β-glucuronidase/aryl sulfatase for 12 h, the protein was precipitated with perchloric acid. The analytes were extracted with vortex mixer by acetonitrile after adjusting the pH value to nine, and then the extracts were purified using mixed adsorbent by dSPE. After the separation on a novel mixed-mode column of Poroshell 120 Phenyl-Hexyl (100 mm×2.1 mm, 4.0 μ m), the qualitative and quantitative analyses of the 26 analytes were operated by electrospray ionization mass spectrometry in the positive mode using multiple reaction monitoring (MRM). The correlation coefficients of linear calibration curves were over 0.99 in the corresponding concentration ranges. The average recoveries of the 26 β-agonists ranged from 65.3% to 108.5%, and the relative standard deviations (RSDs) were 2.7%-13.3% in spiked sample at three levels. The limits of detection (LODs, S/N=3) and the limits of quantification (LOQs, S/N=10) were 0.03-0.1 μ g/kg and 0.1-1.0 μ g/kg, respectively. The method is low cost, sensitive, reliable and suitable for the determination of residues of the 26 β-agonists in pork products.

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Structure characterization of the degradation products of terazosin hydrochloride SUN Yuming, LI Ying, WANG Yueyue, ZHANG Hua, WANG Yulin 2016, 34 (5):  490-497.  DOI: 10.3724/SP.J.1123.2015.12006 Abstract ( 465 )   [Full Text(HTML)] () PDF (919KB) ( 111 )   Terazosin hydrochloride is a selective α1-adrenergic blocker used in the treatment of hypertension and benign prostatic hyperplasia. A high performance liquid chromatography-multistage mass spectrometry with high resolution (HPLC-HRMSn) method was used to detect and identify the degradation products of terazosin hydrochloride treated under stressed oxidation condition. There were 15 degradation products detected. Seven of them were the same as those found in the related references, and the other eight of them were newly found and identified. The main degradation pathways are the hydrolysis of amide bond, hydroxylation, carbonylation and secondary degradation pathways by the combination of the above three ways.

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Determination of anion impurities in barium carbonate by ion chromatography with membrane treatment ZHU Binhe, ZHANG Peimin, GUO Weiqiang, LI Gang, JIANG Xinhua, WU Shuchao, ZHU Yan 2016, 34 (5):  498-501.  DOI: 10.3724/SP.J.1123.2016.01026 Abstract ( 482 )   [Full Text(HTML)] () PDF (785KB) ( 87 )   An ion chromatographic (IC) method with membrane treatment was developed for the simultaneous determination of anions (F-, SO42- and NO3-) in barium carbonate. The cation exchange membrane was applied in providing H+ in hydrochloric acid to dissolve barium carbonate and to prevent anions dissolving into the solution from hydrochloric acid. After pre-treatment by acid dissolution and membrane treatment, the sample was diluted for 100 times and filtrated by a 0.22 μ m membrane, then analyzed by IC using 20 mmol/L KOH as the eluent. The target anions were separated by an Ion Pac AG11-HC (50 mm×4 mm) and an Ion Pac AS11-HC (250 mm×4 mm) ion-exchange columns and detected by suppressed conductivity detection with 50 mA current. Under the optimized separation conditions, the calibration curves showed good linearity (R2≥0.9996) in the range of 0.01-5.00 mg/L. The limits of detection were in the range of 1.37-9.45 μ g/L with the relative standard deviations (RSDs) of 1.87%-2.19%. The recoveries of F-, SO42- and NO3- anions were between 84.0% and 106.2%. This method can determine the three inorganic anions (F-, SO42- and NO3-) in barium carbonate fast and accurately. It is suitable for the simultaneous separation and detection of trace inorganic anions in insoluble products.

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Determination of 28 phthalate esters in baked foods by gas chromatography-triple quadrupole mass spectrometry LI Rong, BO Yanna, LU Junwen, LIN Qinbao, HUANG Zhiqiang, CHEN Lisi 2016, 34 (5):  502-511.  DOI: 10.3724/SP.J.1123.2015.12035 Abstract ( 419 )   [Full Text(HTML)] () PDF (2905KB) ( 105 )   An efficient method using gas chromatography-triple quadrupole mass spectrometry for the determination of 28 phthalate ester residues in bakery foods was established. The samples were extracted with ethyl acetate, and cleaned up with neutral alumina. The separation was performed on a TR-5MS capillary column (30 m×0.25 mm×0.25 μ m) by programmed temperature vaporization (PTV) with splitless mode. Meanwhile the identification and quantification were performed by GC-MS/MS in selected reaction monitoring (SRM) mode and using the internal standard method. The calibration curves of the 27 phthalate esters showed good linearities in the range of 0.05-10 mg/L, except diisononyl ortho-phthalate (DINP) which was in the range of 0.1-20 mg/L, with the correlation coefficients not less 0.9962. The limits of detection (LODs) were 0.1-9.8 μ g/kg and the limits of quantification (LOQs) were 0.4-32.6 μ g/kg. With the proposed method, the spiked recoveries were evaluated in four types of baked foods (bread, biscuits, cakes, stuffing) at low, medium and high concentrations. The results showed that the average recoveries of the 28 PAEs were in the range of 81.0%-117%, and the relative standard deviations (RSDs, n=6) were in the range of 1.3%-13.6%. The method was successfully applied in the investigation of the PAEs distribution in baked foods. The method is suitable for the determination of the 28 PAEs in baked foods with easy operation, high accuracy and precision.

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Analysis of 23 esters of flavor additive in tobacco products by gas chromatography-tandem mass spectrometry coupled with solid-phase extraction ZHENG Yang, XU Xiuli, JI Shunli, YUAN Fei, HUANG Zhiqiang, YANG Bingcheng, ZHANG Feng 2016, 34 (5):  512-519.  DOI: 10.3724/SP.J.1123.2015.12020 Abstract ( 439 )   [Full Text(HTML)] () PDF (1298KB) ( 98 )   An analytical method for the simultaneous determination of 23 esters of flavor additive in tobacco products was established based on optimized solid-phase extraction (SPE) with gas chromatography-tandem mass spectrometry (GC-MS/MS). The samples were extracted with ethyl acetate, cleaned up by an amino SPE column. After conditioning step, the extracts were eluted by 4 mL ethyl acetate, and then were determined by GC-MS/MS in multi-reaction monitoring (MRM) mode. The results showed that all the 23 ester flavor additives had good linearity in the range of 20.0-500.0 μ g/L, with the correlation coefficients (r2) better than 0.996. The limits of detection (LODs) and limits of quantitation (LOQs) of these additives were in the ranges of 1.9-13.6 μ g/kg and 6.3-45.3 μ g/kg, respectively. The average recoveries of the 23 analysts were in the range of 62.1%-91.4% at the spiked levels of 1, 1.5, 2 times LOQ with relative standard deviations (RSDs) typically lower than 7%. The accurate, reliable and sensitive method can be applied to the determination of the 23 esters of flavor additive in tobacco products for rapid screening and quantitative analysis. The method also offered an opportunity to detect more ester additives that may be added in tobacco products.

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Determination of trans-fatty acid isomers in human milk fat by gas chromatography-mass spectrometry LIN Qi, LI Guobo, GE Pin, XU Rongxian, LIN Guobin 2016, 34 (5):  520-527.  DOI: 10.3724/SP.J.1123.2016.01003 Abstract ( 449 )   [Full Text(HTML)] () PDF (1483KB) ( 88 )   A method for the determination of trans-fatty acid isomers in human milk fat was developed by gas chromatography-mass spectrometry (GC-MS), and applied to analyze TFAs in human milk fat. The fat was extracted with diethylether and petroleum ether after ammonia hydrolysis of human milk. C21: 0 internal standard and boron trifluoride methanol solution were added to the extract for fat esterification. The solution then was refluxed in 80℃ water bath for 15 min. Finally the trans-fatty acid methyl ester isomers were extracted with hexane, and analyzed by GC-MS. GC conditions were as follows: an HP-88 column (100 m×0.25 mm×0.2 μ m) with inlet temperature of 260℃, at a split ratio of 10: 1, and a He flow rate of 1 mL/min. The initial column temperature was 140℃ (held for 5 min), then raised up to 240℃ at a rate of 4℃/min (held for 15 min). The electronic ionization (EI) source energy was 70 eV, with auxiliary (AUX) temperature of 280℃, ion source temperature of 230℃, quadrupole temperature of 150℃ in selected ion monitoring (SIM) mode. This method can analyze the 18 TFAs. The method detection limits (MDLs) of 12 TFAs were 4.0-47.1 mg/kg, and the average recoveries were 80%-113% with the relative standard deviation (RSD, n=6) range of 2.9%-14.5%. TFAs were detected in some real samples and the contents were 9.5-46.9 mg/kg. The method is reliable and sensitive, and would be better if the background interference of fatty acids should be diminished by silver ion solid phase extraction.

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Determination of phthalate monoesters and diesters in urine by solid-phase extraction and gas chromatography-mass spectrometry LIN Xingtao, WANG Xiaoyi, ZHAO Jingqiang 2016, 34 (5):  528-532.  DOI: 10.3724/SP.J.1123.2016.01024 Abstract ( 456 )   [Full Text(HTML)] () PDF (893KB) ( 106 )   A method for the determination of phthalate monoesters and diesters in urine by solid-phase extraction and gas chromatography-mass spectrometry (SPE-GC-MS) was developed. After urine enzymatic hydrolysis by β-glucuronidase, the sample was pretreated by SPE. Phthalate monoesters and diesters were eluted by acetonitrile, ethyl acetate and ethyl ester-n-hexane (1: 19, v/v), separately. The mixture of the elution was dried by N2 and derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide before GC-MS analysis. Good linear relationships were obtained in the range of 5-1000 μ g/L. The limits of detection were between 0.3 and 1.1 μ g/L. The recoveries of phthalate monoesters and diesters were in the range of 77.9%-97.7% and the relative standard deviations (RSDs) were 3.7%-10.9%. The method was applied to analyze 50 urine samples. Seven compounds, such as di-2-ethylhexyl phthalate (DEHP), were detected. The mean concentrations were between 6.0 and 142.7 μ g/L. The method is highly accurate, reliable and sensitive for monitoring phthalate monoesters and diesters in urine.

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Determination of vitamin A reserved in human liver by stable isotope dilution technique WANG Li, SHAO Yingying, LI Lei, WANG Zhixu 2016, 34 (5):  533-537.  DOI: 10.3724/SP.J.1123.2015.12019 Abstract ( 499 )   [Full Text(HTML)] () PDF (806KB) ( 92 )   An analytical method for the determination of vitamin A (VA) reserved in human liver by stable isotope dilution technique and high performance liquid chromatography-gas chromatography/negative ion chemical ionization/mass spectrometry (HPLC-GC/NCI/MS) was developed. Before the test, deuterium labelled retinol acetate (2H8-RAC) (1 mg) was ingested by the volunteers. After 21 days, the blood samples were collected and the serum was separated. The VA was extracted by n-hexane and purified by HPLC. Then the purified VA was dried under nitrogen for further derivatization. The derivative was finally detected by GC/NCI/MS. The concentration of the VA in the liver was calculated by using the formula of Furr-Olson. Under the optimized conditions, more than 85% of the VA in the serum samples could be collected, purified and detected. The detection precision (relative standard deviation, RSD, n=6) was less than 10% and the quantitative limit reached 26.4 μ g/L, which met the marked and unmarked VA detection requirements. Compared with the current domestic VA evaluation method, this method can more objectively reflect human VA nutrition level. When this determination technology combines with VA intervention experiment, it could evaluate a dietary intake level of VA to maintain a stability reserve level. At the same time, it also plays an important role in the research on biological conversion efficiency of carotene ingestion.

Technical Notes

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Rapid screening of 10 drugs in blood using ultra performance liquid chromatography with high resolution quadrupole-time-of-flight mass spectrometry SHI Yintao, WANG Huijun, GUO Jingqi, DING Jing, WANG Junwei 2016, 34 (5):  538-542.  DOI: 10.3724/SP.J.1123.2016.01028 Abstract ( 455 )   [Full Text(HTML)] () PDF (940KB) ( 102 )   A high-throughput method was developed for rapid screening of 10 drugs in blood by ultra performance liquid chromatography with high resolution quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS). The sample was extracted by ethyl acetate, the extraction solution was concentrated to near dryness, and dissolved with methanol. Then the sample was passed through a 0.22 μ m membrane. The separation of the 10 target compounds was performed on a Waters ACQUITY UPLC@BEH C18 column (100 mm×2.1 mm, 1.7 μ m) with gradient elution using methanol and 0.1% (v/v) formic acid aqueous solution as mobile phases, and analyzed by UPLC-Q-TOF/MS under electrospray ionization (ESI) mode with scanning range of m/z 50-1000. Rapid screening can be achieved using MS matching scores, deviation of retention time, measured mass, isotopic abundance matching scores, isotope spacing match scores and MS/MS matching scores. Good linearities were observed in the range of 10.0-500.0 μ g/L with the correlation coefficients from 0.9908 to 0.9958. The limits of detection and the limits of quantification were 1.0-2.0 μ g/L and 4.0-8.0 μ g/L, respectively. The spiked recoveries were 56.7%-83.0% with the relative standard deviations of 3.6%-8.9%. The result screening database was built using Agilent Mass Hunter PCDL Manager software and then used for the analysis of spiked samples. MS matching scores, isotopic abundance matching scores, isotope spacing matching scores (all > 90 points) and MS/MS matching scores (> 70 points) were applied to identify the drugs. The results showed that all the spiked drugs could be correctly identified with low deviations of retention time (< 0.1 min) and mass (< 1 mDa). The developed method is suitable for the screening and confirmation of the drugs in forensic and clinical analytical toxicology.