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Chinese Journal of Chromatography
2018, Vol. 36, No. 6
Online: 08 June 2018

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System of simultaneous extraction and cleaning of 99 veterinary drugs in food LI Shuang, CHEN Shubing, LI Luqing, XU Xuwen, CHEN Xianfeng, ZHONG Yingying, ZHANG Yaheng, WANG Chuanxian 2018, 36 (6):  506-517.  DOI: 10.3724/SP.J.1123.2018.02023 Abstract ( 404 )   [Full Text(HTML)] () PDF (1284KB) ( 74 )   We established a system for the simultaneous extraction and cleaning of 99 veterinary drugs from food by ultra-performance liquid chromatography coupled with quadrupole electrostatic field-orbital trap-high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS). The system is based on the supported liquid-liquid extraction technology through one-off pretreatment, which covers the common eight categories of physical and chemical properties, and the extraction and purification of 99 different veterinary drug residues. At the same time, the one-step multi residue screening of 99 veterinary drug residues has been realized using HRMS. The results showed that the method was suitable for extraction from milk, pork, and fish. The 99 veterinary drugs showed a good linear relationship in the concentration range of 0.001-0.1 μg/mL, the limit of quantification was 0.5-20.0 μg/kg, the average recoveries were 60%-120%, and the relative standard deviations (RSDs) were not more than 15%. The pre-processing and instrumental analysis of this method have high detection efficiency, strong maneuver ability, and strong compatibility with different physical and chemical compounds. Moreover, the detection limit can meet all the objects of the test and greatly reduce the detection cost.

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Determination of trace pentachlorophenol and its sodium salt in animal-origin foods by QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry WANG Lianzhu, FANG Enhua, WANG Caijuan, CHEN Yong, LIN Zixu, XU Dunming 2018, 36 (6):  518-522.  DOI: 10.3724/SP.J.1123.2018.03017 Abstract ( 491 )   [Full Text(HTML)] () PDF (740KB) ( 168 )   A method was developed for the determination of trace pentachlorophenol and its sodium salt in animal-origin foods by modified QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Sodium pentachlorophenolate in samples was converted to pentachlorophenol under acidic condition. The pentachlorophenol was extracted twice with acetonitrile containing 1% (v/v) acetic acid by ultrasonic extraction. The extracts were purified by dispersive solid-phase extraction. The usages of dispersive sorbents were optimized based on the recoveries and matrix effects. Chromatographic analysis was conducted on a Waters Acquity UPLC HSS T3 column with gradient elution. The pentachlorophenol was further analyzed by negative electrospray ionization under the multiple reaction monitoring mode. The recoveries at fortification levels of 1.0, 2.0 and 10.0 μg/kg in six matrices (pork, pork liver, chicken, fish, milk and egg) ranged from 73.2% to 108.4% with the relative standard deviations of 4.0%-14.8%. The limits of quantification (S/N>10) were 1.0 μg/kg. The method is simple, sensitive, accurate, economical and environmentally safe, and is suitable for the determination of the trace pentachlorophenol and its sodium salt in animal-origin foods.

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Determination of deltamethrin and its toxicity biomarkers in rabbit urine by high performance liquid chromatography-tandem mass spectrometry CAO Wenqing, WU Zhenxing, LIANG Chengzhu, JING Ping, CUI Shuhua, YANG Guipeng, LIN Liming 2018, 36 (6):  523-530.  DOI: 10.3724/SP.J.1123.2018.03002 Abstract ( 410 )   [Full Text(HTML)] () PDF (795KB) ( 60 )   A method was developed for the determination of biomarkers related to toxicity of deltamethrin in rabbit urine by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The target analytes in this method are as follows:deltamethrin and its two metabolites (1R-cis)-3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropane carboxylic acid (dibromochrysanthemic acid) and 3-phenoxybenzoic acid (3-PBA), and five toxic biomarkers, viz. serotonin hydrochloride (5-HT), 5-hydroxyindole-3-acetic acid (5-HIAA), 3-nitropropionic acid (3-NPA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and 6-methoxyguanine. Urine samples were cleaned by matrix solid-phase dispersion extraction (MSPD) with diatomite; and protein was precipitated with trichloroacetic acid; and then the sample solutions were purified with hydrophilic-lipophilic balance (HLB) solid-phase extraction cartridges. The biomarkers were analyzed with electrospray ionization (ESI) in a positive and negative switching scan mode, in which the positive scan mode was used for deltamethrin, 5-HT, 5-HIAA, 8-OHdG, and 6-methoxyguanine, and the negative scan mode was used for (1R-cis)-3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropane, 3-PBA, and 3-NPA. The target compounds were quantified with the external standard using matrix calibration curves. The linear regression curves of the eight target compounds were linear with correlation coefficients no less than 0.9914. The LOD and LOQ of 5-HIAA were 20 μg/L and 50 μg/L, respectively, and the LODs and LOQs of the other analytes were 0.2-5.0 μg/L and 0.5-10 μg/L, respectively. The average recoveries of the analytes spiked in rabbit urine ranged from 74.2% to 98.7% at three levels, with relative standard deviations (RSDs) no more than 12%. The method was simple, fast, accurate, sensitive, and suitable for the detection for the exposure evaluation of deltamethrin.

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Determination of 53 pesticide residues in tea by gas chromatography-tandem mass spectrometry and double internal standard method GAO Yixian, CHEN Pinghong, NIE Dandan 2018, 36 (6):  531-540.  DOI: 10.3724/SP.J.1123.2018.03036 Abstract ( 603 )   [Full Text(HTML)] () PDF (1128KB) ( 230 )   A gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) method with tandem double columns was established for the determination of 53 pesticide residues in tea. The sample was extracted by acetonitrile with buffering salts of QuEChERS method, cleaned up with an ENVI-Carb/NH2 solid-phase extractant, and determined by GC-MS/MS. To reduce the matrix effect in GC-MS/MS, gulonic acid lactone and sorbitol were added to the standard solutions as protectants; additionally, anthraquione-D8 and triphenyl phosphate were used as double internal standards. The linear ranges were from 20 to 500 μg/L for 52 pesticides, and from 40 to 1000 μg/L for cypermethrin, with correlation coefficients higher than 0.99. The limits of quantification (LOQs) of 28 pesticides were less than 10 μg/kg, and the LOQs of the other 25 pesticides ranged from 10 to 20 μg/kg. The recoveries were in the range 72.5%-130.9%, and the relative standard deviations (RSDs) were in the range 0.4%-19.4%. This method is simple, rapid, sensitive, and reliable for the simultaneous identification and quantification of multiple residues in tea.

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Determination of cinnamaldehyde residues in fresh fruits and meats by modified QuEChERS combined with gas chromatography-tandem mass spectrometry LIU Ying, ZHANG Rong, CUI Fengyun, HAN Shen 2018, 36 (6):  541-546.  DOI: 10.3724/SP.J.1123.2017.11035 Abstract ( 318 )   [Full Text(HTML)] () PDF (878KB) ( 49 )   A method for the determination of cinnamaldehyde residues in fresh fruits and meats by gas chromatography-tandem mass spectrometry (GC-MS) coupled with modified QuEChERS was developed. The samples were extracted with ethyl acetate. Solid phase extraction agents such as graphitized carbon black (GCB), primary-secondary amine (PSA) and octadecyl bonded silica (C18) were used for adsorption and purification. The extracts were detected by electron impact ionization in selected ion monitoring (SIM) mode and quantified using external standard method. The results revealed correlation coefficients (R2) greater than 0.999 in the range of 0.01-0.5 mg/L. The limits of quantification (LOQs) were 0.05 to 0.1 mg/kg. The recoveries at the three spiked levels ranged from 81.9% to 104.5% with the relative standard deviations (RSDs) ranging from 1.1% to 8.6%. The proposed method is efficient, sensitive, reliable, and is suitable for the trace determination of the cinnamaldehyde residues in fresh fruits and meats.

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Quick determination of fipronil and its metabolites in eggs by gas chromatography-triple quadrupole mass spectrometry DENG Wujian, WU Weidong, ZHAO Xu, LIANG Hong, LIANG Shuwen, JIN Baohui, WANG Shen 2018, 36 (6):  547-551.  DOI: 10.3724/SP.J.1123.2017.09043 Abstract ( 366 )   [Full Text(HTML)] () PDF (733KB) ( 105 )   A method was established for the simultaneous determination of fipronil and its metabolites in eggs by gas chromatography-tandem mass spectrometry coupled with QuEChERS. Fipronil and its metabolites were extracted from eggs with acetonitrile, and the solution was dehydrated with 150 mg anhydrous magnesium sulfate. The extracts were purified with 50 mg N-propyl ethylenediamine (PSA) and 50 mg C18, and a capillary column pesticide Ⅱ was used. The analytes were detected in timed selected reaction monitoring (timed-SRM) mode, and were quantified using external standard method with matrix correction standard curves. A good linearity in the range of 1.0-200 μg/L with correlation coefficients (R2)>0.999 was observed. The limits of quantification (LOQs) were between 0.5 and 1.0 μg/kg. The recoveries at three spiked levels (2.0, 5.0 and 10.0 μg/kg) were in the range of 87.8% to 111.5% with RSDs between 2.0% and 9.2% (n=3). This new method satisfied the related regulations of the European Union for the determination of fipronil and its metabolites in eggs.

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Determination of pendimethalin residues in Procambarus clarkii by high performance liquid chromatography-triple quadrupole mass spectrometry YANG Qiuhong, LIU Huan, ZOU Puxin, QI Minglong, LIU Yongtao, AI Xiaohui 2018, 36 (6):  552-556.  DOI: 10.3724/SP.J.1123.2018.01008 Abstract ( 344 )   [Full Text(HTML)] () PDF (991KB) ( 120 )   A novel method was developed for the determination of pendimethalin in Procambarus clarkii by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Samples were extracted with ethyl acetate containing 0.1%(v/v) acetic acid, and the extracts were dried at 35℃. The final extracts were redissolved with methanol-water (8:2, v/v) containing 0.1%(v/v) acetic acid and cleaned up by acidic alumina column and graphitized carbon black (GCB). The prepared samples were separated on a Symmetry C18 column (100 mm×2.1 mm, 3.5 μm) and characterized using a heated electrospray ionization (HESI) source in the positive ion multiple reaction monitoring mode. Under optimum experimental conditions, the standard curve was linear in the range of 1.0-20.0 μg/L with the correlation coefficient of 0.9960. The limit of detection was 0.5 μg/kg. The spiked recoveries of the pendimethalin in the Procambarus clarkii samples ranged from 63.3% to 104.7% with RSDs of 6.9%-14.5% (n=7). The proposed method is quick, simple and sensitive, and suitable for the rapid determination and analysis of pendimethalin in Procambarus clarkii samples.

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Effects of substituted functional groups of cations on retention performance of ionic liquid stationary phases in gas chromatography WANG Zhonglai, WANG Yunfeng, SHI Enlin, YU Wen, ZHANG Lulu, YU Farong 2018, 36 (6):  557-565.  DOI: 10.3724/SP.J.1123.2018.02025 Abstract ( 301 )   [Full Text(HTML)] () PDF (842KB) ( 39 )   Thirteen stationary phases comprising a polyvinyl imidazolium ionic liquid (IL) in which cations containing propyl, butyl, nonyl, ethyl-phenyl, or cyan methyl functional groups are paired with bis(trifluoromethanesulfonyl) imide ([NTf2]-), trifluoromethanesulfonate ([TFO]-), and hexafluorophosphate ([PF6]-) were synthesized and directly coated inside capillary fused silica tubing for use in gas chromatography. The relationship between the structure of the ILs and the McReynolds constant, thermal stability, and retention behavior of the test compound on the prepared fused silica columns was examined and discussed. The influence of the cationic substituents on retention performance of stationary phases was also studied. The variation in the retention index of the test compound with temperature was also investigated. The results indicated that the synthesized ILs have strong polarity, and that their retention performance is closely related to not only the properties of the cationic substituent but also the structure of the substituted groups and the anion. In the temperature range investigated, the variation in the retention index of the tested compounds was the same as that of conventional chromatographic stationary phases.

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Simultaneous determination of six zeranols in milk samples by immunoaffinity solid phase extraction coupled with ultra-performance convergence chromatography-tandem mass spectrometry ZHANG Luxing, SUN Jieyin, WANG Yanhui, WU Huifang, YU Songlin 2018, 36 (6):  566-572.  DOI: 10.3724/SP.J.1123.2018.02008 Abstract ( 442 )   [Full Text(HTML)] () PDF (974KB) ( 44 )   A method was developed for the simultaneous determination of α-zearalanol, β-zearalanol, α-zearalenol, β-zearalenol, zearalenone and zearalanone residues in milk samples by ultra-performance convergence chromatography-tandem mass spectrometry (UPC2-MS/MS) after immunoaffinity column-solid phase extraction (IAC-SPE). The sample was diluted with deionized water and cleaned with IAC-SPE. The chromatographic separation was performed on an ACQUITY UPC2 Torus 2-PIC column (50 mm×3.0 mm, 1.7 μm) using the mobile phases of supercritical carbon dioxide and methanol containing 0.1% (v/v) formic acid with gradient elution. The separated compounds were detected in negative electrospray ionization (ESI-) mode. The results showed no significant matrix effect after cleaning by IAC-SPE. The calibration curves of the six compounds were linear in the range of 1-200 ng/mL (correlation coefficients (r2) ≥ 0.9957). The recoveries were 75.9%-106.5% in the three spiked levels, and the intra-day and inter-day precisions were no more than 11.4%. The method is specific, environment friendly, and is suitable for the rapid determination of α-zearalanol, β-zearalanol, α-zearalenol, β-zearalenol, zearalenone and zearalanone residues in milk samples.

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Determination of four phenolic estrogens in water samples by pressure-assisted electrokinetic injection coupled with capillary electrophoresis GAO Fangfang, LIU Junying, LU Wenhui, LI Jinhua, LIU Huitao 2018, 36 (6):  573-577.  DOI: 10.3724/SP.J.1123.2018.01011 Abstract ( 307 )   [Full Text(HTML)] () PDF (751KB) ( 33 )   A capillary electrophoresis (CE) method was developed for the simultaneous separation and determination of four phenolic estrogens (PEs), in which pressure-assisted electrokinetic injection (PAEKI) was adopted as the on-line concentration method to enrich the PEs. Several parameters affecting PAEKI conditions such as injection voltage and injection time, were systematically investigated and compared with the usual parameters. Under the optimized PAEKI conditions (-9 kV, 0.3 psi (ca. 2.1 kPa), 0.4 min), the four PEs separated completely within 7 min. Good linearities were attained in the range of 0.05-5 mg/L for hexestrol and dienestrol, and 0.1-10 mg/L for bisphenol A and diethylstilbestrol, with correlation coefficients (r) over 0.9936. The limits of detection (S/N=3) were 0.0071-0.017 mg/L, and enrichment factors ranged from 11 to 15 compared to normal hydrodynamic injection. The combined micellar electrokinetic chromatographic-PAEKI method developed was used to determine the PEs in tap water and lake water samples; limits of quantification (S/N=10) of 0.029-0.064 mg/L and 0.033-0.079 mg/L were attained, respectively, by the two sample types. Furthermore, recoveries ranged from 75.6% to 110.1% with relative standard deviations (n=5) within 4.6%-11.8%. To use this PAEKI method, researchers would only need to adjust the parameters of the CE apparatus to perform on-line enrichment of analytes, without using other reagents; this demonstrates the simplicity, rapidity, and highly automated nature of this method.