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Chinese Journal of Chromatography
2019, Vol. 37, No. 10
Online: 08 October 2019

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Volume 37, Number 10 Content 2019, 37 (10):  0-0.  Abstract ( 11 )   PDF (5182KB) ( 12 )

Special Issue for Applications of Solid Phase Extraction and QuEChERS

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Determination of higenamine in Chinese herbal medicine, condiments, and topical medicine by QuEChERS combined with liquid chromatography-tandem mass spectrometry WANG Han, TANG Yizhu, ZHAO Xiaoya, YE Cheng, GUO Shaofei, LUO Jing, XIONG Lu, CAO Wei, WU Jian'an, WANG Peng 2019, 37 (10):  1036-1041.  DOI: 10.3724/SP.J.1123.2019.01055 Abstract ( 188 )   [Full Text(HTML)] () PDF (1814KB) ( 320 )   A method combining QuEChERS with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of higenamine in Chinese herbal medicine, condiments, and topical medicine. The sample was subjected to extraction using a formic acid-ethanol mixture, followed by purification of the QuEChERS sorbents; then, the extraction solution was introduced into the LC-MS/MS system for detection in multiple reaction monitoring (MRM) mode. Under the optimal conditions, the detection limit of the developed method was 0.03 ng/g, and the linear range was 0.10-100 ng/g with a relative standard deviation (RSD) of 4.33% (0.5 ng/g, n=7). The method was then applied to the determination of higenamine in 13 kinds of Chinese herbal medicine, four kinds of condiments, and a topical medicine. Higenamine was detected in dried lotus leaf, dried lotus seed, Chinese yam, Yuzhu, Yam, Sichuan pepper, Cassia, and the topical medicine at 9667.6, 1183.8, 21.5, 8.2, 8.5, 148.6, 21.3, and 173.3 μg/kg, respectively. The recoveries of higenamine in Sichuan pepper and cassia was 92.6%-109.8%. In conclusion, the method is fast, simple, reliable, and suitable for use in batch operation.

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Determination of pesticide residues in wolfberry using QuEChERS-gas chromatography-tandem mass spectrometry WANG Fanghuan, REN Cuijuan, MA Hui, LI Ping, HAO Junhu, CHEN Lin, SUN Min 2019, 37 (10):  1042-1047.  DOI: 10.3724/SP.J.1123.2019.04014 Abstract ( 119 )   [Full Text(HTML)] () PDF (1296KB) ( 120 )   A method based on QuEChERS-gas chromatography-tandem mass spectrometry (GC-MS/MS) was established for the determination of 20 pesticide residues in wolfberry. The samples were extracted with acetonitrile. The extract was purified with PSA (primary secondary amine), GCB (graphite carbon black) and C18 to suppress the matrix in wolfberry. The analytical results showed that the calibration curves for the 20 pesticides obtained by GC-MS/MS were linear in the range of 5-500 μg/L, with the correlation coefficients higher than 0.99. The recoveries ranged from 70.02% to 110.78% with relative standard deviations (RSDs) ranging from 2.05% to 9.53%. This method has the advantages of being time-saving, convenient and sensitive. The proposed method can simultaneously detect organic phosphorus and organic chlorine pesticides residues with a good performance in terms of qualitative and quantitative detection.

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Determination of multiple chloropropanols in soy sauce by dispersive solid phase extraction-gas chromatography-high resolution mass spectrometry HUANG Chaoqun, CHEN Qinke, CHEN Li, WANG Yunyu, MA Zhe, SHEN Mi, HUANG Jiabo 2019, 37 (10):  1048-1052.  DOI: 10.3724/SP.J.1123.2019.03016 Abstract ( 98 )   [Full Text(HTML)] () PDF (854KB) ( 89 )   A method for the rapid screening of 1,3-dichloro-2-propanol, 2,3-dichloro-1-propanol,3-monochloropropane-1,2-diol, and 2-monochloropropane-1,3-diol in soy sauce was developed based on dispersive solid phase extraction-gas chromatography-high resolution mass spectrometry (GC-HRMS). The samples were extracted by ethyl acetate, cleaned up using N-propylethylenediamine and detected by GC-HRMS. The chloropropanols were quantified by the internal standard method. The results demonstrated that the limits of quantitation of the four chloropropanols were in the range of 0.5-10 μg/kg. The recoveries of the four chloropropanols in soy sauce spiked with three levels varied from 78% to 103%, and the relative standard deviations were no more than 8.8%. The proposed method is simple, accurate, sensitive and suitable for the rapid screening of the four chloropropanols in soy sauce.

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Determination of 2,4-diaminotoluene in Mianpi composite packaging film bags by ion-exchange solid-phase extraction-gas chromatography-mass spectrometry LU Zhiyuan, WANG Bing, TIAN Na, ZHANG Yaowu, ZHANG Xinyu, LIU Jia, LÜ Yan 2019, 37 (10):  1053-1058.  DOI: 10.3724/SP.J.1123.2019.01024 Abstract ( 61 )   [Full Text(HTML)] () PDF (979KB) ( 49 )   A method for the determination of 2,4-diaminotoluene in Mianpi composite packaging film bags was established based on ion-exchange solid-phase extraction-gas chromatography-mass spectrometry (GC-MS). The samples were immersed in 4% (v/v) acetic acid solution. 2,4-Diaminotoluene was enriched from a 50.0 mL soak solution with an activated and balanced MCX solid-phase extraction column. The MCX column was washed with 5.0 mL water and eluted with 3.0 mL ammoniated methanol. 2,4-Diaminotoluene was detected quantitatively by GC-MS after derivatization with heptafluorobutyric acid anhydride. In the mass concentration range of 1-50 μg/L, the linear correlation coefficient (r) was 0.9991. The limit of detection (LOD, S/N=3) was 0.2 μg/L, and the limit of quantification (LOQ, S/N=10) was 0.6 μg/L. The recovery of 2,4-diaminotoluene was in the range of 89.0%-94.2%. The relative standard deviations (RSDs) were 1.9%-3.6%. This method requires neither pH adjustment of the soak solution in the pre-processing step nor liquid-liquid extraction. With this method, the pre-processing step is greatly simplified and there is minimal consumption of organic solvents. Further, the method is simple, convenient, and accurate, and it is suitable for the determination of 2,4-diaminotoluene in Mianpi composite packaging film bags.

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Determination of 3-methyl-quinoxaline-2-carboxylic acid residue in pork by high performance liquid chromatography-tandem mass spectrometry WEI Minzhi, WAN Jianchun, ZHANG Fusheng, PAN Hua 2019, 37 (10):  1059-1063.  DOI: 10.3724/SP.J.1123.2019.04050 Abstract ( 54 )   [Full Text(HTML)] () PDF (847KB) ( 56 )   A method was developed for the simultaneous quantitative and confirmatory determination of 3-methylquinoxaline-2-carboxylic acid (MQCA) residues in pork by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was hydrolyzed with 0.3 mol/L hydrochloric acid solution, and MQCA was extracted by water bath oscillation. MQCA was first extracted with acetonitrile and ethyl acetate and then re-extracted from the extraction solution with 0.1 mol/L sodium hydroxide solution. Then MQCA was purified by an anion exchange solid phase extraction column. The chromatographic separation was performed using an Agilent Eclipse Plus C18 column (50 mm×3.0 mm, 1.8 μm). The quantitative analysis was performed by the matrix matching addition method. The correlation coefficient of MQCA in the range of 1.0-50 μg/L was greater than 0.99. The recovery was 90.5%-119.6% at the spiked levels of 0.5, 1.0 and 5.0 μg/kg, and the relative standard deviation was 3.14%-4.22%. The method can be used for the rapid quantitative determination of 3-methylquinoxaline-2-carboxylic acid residues in pork.

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Determination of chlorate and perchlorate in milk power by high-performance liquid chromatography-tandem mass spectrometry ZHOU Xiaoqing, LÜ Xiaoli, WAN Jianchun, GUO Ping, GUO Dan, XI Huiting 2019, 37 (10):  1064-1070.  DOI: 10.3724/SP.J.1123.2019.04052 Abstract ( 217 )   [Full Text(HTML)] () PDF (1082KB) ( 166 )   An analytical method based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for detecting chlorate and perchlorate residues in milk power. Chlorate and perchlorate in milk power were extracted using a 0.1% (v/v) formic acid-acetonitrile solution. The extract was centrifuged at 10000 r/min for 10 min, and the supernatant was cleaned up on a PRiME HLB column. Separation of chlorate and perchlorate was performed on an ion-exchange column (Thermo Scientific Acclaim TRINITY P1, 50 mm×2.1 mm, 3 μm) by gradient elution using acetonitrile and 20 mmol/L ammonium acetate solution as the mobile phase. The analytes were identified by MS/MS. Quantification was achieved using internal standards. Chlorate and perchlorate demonstrated good linearity in the ranges of 2.0-40.0 and 1.0-20.0 μg/L, respectively, with correlation coefficients (r2) greater than 0.999. The limits of quantification (LOQs) of chlorate and perchlorate were found to be 15.0 and 7.5 μg/kg, respectively. The recoveries of chlorate and perchlorate ranged from 89.24% to 107.85% at the three spike levels of 30.0, 60.0, and 120.0, and 15.0, 30.0, and 60.0 μg/kg, respectively, with relative standard deviations (RSDs) ranging from 3.15% to 10.42% (n=6). This method is convenient, rapid, accurate, and efficient, thus demonstrating its suitability for use in the determination of chlorate and perchlorate in milk power.

Reviews

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Advances in separation techniques for exosomes and their clinical applications GAO Fangyuan, JIAO Fenglong, ZHANG Yangjun, QIN Weijie, QIAN Xiaohong 2019, 37 (10):  1071-1083.  DOI: 10.3724/SP.J.1123.2019.02007 Abstract ( 165 )   [Full Text(HTML)] () PDF (3419KB) ( 211 )   Exosomes are vesicles secreted by many types of cells through exocytosis, and their sizes range from 30 to 200 nm. Exosomes consist of a lipid bilayer membrane, containing a number of bioactive molecules, e. g., proteins, ribose nucleic acid (RNA), and deoxyribo nucleic acid (DNA) derived from the cell of origin. As intercellular communication carriers, exosomes participate in many physiological and pathological processes. Because of the complexity of body fluids, as well as the small size and low density of exosomes, the isolation of exosomes is an essential and challenging step before subsequent analysis and functional studies. This review summarizes the advances in the analytical approaches, characterization methods, biological functions and clinical applications of exosomes, with particular emphasis on exosomes isolation techniques.

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Advances in markers reflecting technological conditions in the liquid milk processing NIE Xuemei, DONG Xuyang, XU Xiuli, ZHANG Feng 2019, 37 (10):  1084-1089.  DOI: 10.3724/SP.J.1123.2019.03010 Abstract ( 77 )   [Full Text(HTML)] () PDF (861KB) ( 96 )   The trade volume of imported dairy products is increasing with the increase of per capita consumption of dairy products, thus it is the great significant thing to control the quality of dairy products from other countries. The investigation finds that the proline content of imported liquid milk ultra high temperature instantaneous sterilization (UHT) milk (commonly known as normal temperature milk) is significantly higher than that of domestic UHT milk, that a risk of overheating and adding reconstituted milk exists for the imported UHT milk. Although it is currently unable to regulate the source and processing technology of imported dairy products, some certain indicators that reflect the process conditions are often used to monitor the quality of dairy products in the field of heat treatment process control of dairy products. Proline is produced during the processing of dairy products and is a marker that reflects the processing conditions. This paper briefly describes the research status of nine markers used to evaluate in the processing of dairy products at home and abroad, with the aim of providing a theoretical basis for improving the regulatory system for the processing of dairy products in China, and to protect consumer rights.

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Preparation of capillary isoelectric focusing with monolithic immobilized pH gradient and its application in determination of isoelectric point of proteins LIU Rangdong, XU Xinyao, WANG Weiwei, WANG Yan, YAN Chao 2019, 37 (10):  1090-1097.  DOI: 10.3724/SP.J.1123.2019.03019 Abstract ( 120 )   [Full Text(HTML)] () PDF (4025KB) ( 111 )   A partially filled monolith was prepared by in situ polymerization, and then carrier ampholytes (CAs, pH 3-10) were immobilized on its surface. For effective utilization of capillary isoelectric focusing (cIEF) with the monolithic immobilized pH gradient (M-IPG), a new online platform was established by the introducing of an eight-way injection valve, a three-way valve and a cross-shaped unit. Besides, a capillary coated with hydroxypropyl cellulose (HPC capillary) was prepared and used to determine the isoelectric points (pI) of trastuzumab and etanercept. In parallel, using the newly built capillary isoelectric focusing platform, the pI values of trastuzumab and etanercept were measured with the M-IPG column, and compared with the results obtained using the HPC capillary. It was found that these two cIEF columns can be effectively used to separate proteins and determine the pI values of monoclonal antibodies and fusion proteins in protein drugs. Moreover, the measured pI values were consistent with those estimated using the HPC capillary.

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Determination of 11 sulfonamides in pork by two-step liquid-liquid extraction-solid phase extraction purification coupled with high performance liquid chromatography-tandem mass spectrometry LIU Peiyong, ZHANG Hui, MI Zhijin, ZHANG Liangcheng, ZHANG Guangren 2019, 37 (10):  1098-1104.  DOI: 10.3724/SP.J.1123.2019.04005 Abstract ( 77 )   [Full Text(HTML)] () PDF (1824KB) ( 79 )   A method based on two-step liquid-liquid extraction-solid phase extraction purification coupled with high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of 11 common sulfonamides in pork. The samples were extracted first with ethyl acetate containing 2%(v/v) formic acid and then with acetone for the second step. The supernatant was degreased with n-hexane and cleaned using an Oasis MCX SPE column. Finally, nitrogen was blown over the obtained mixture, and the mixture was filtered for conducting HPLC-MS/MS analysis. The sulfonamides were detected in the multiple reaction monitoring positive ion mode, and quantification was performed by employing the external standard method with matrix calibration curves. All the 11 sulfonamides demonstrated good linearity in the range of 20-400 μg/L, with the correlation coefficient (r2) higher than 0.99. The limits of detection (LODs; S/N=3) and limits of quantification (LOQs; S/N=10) were found to be in the ranges of 0.1-1.0 μg/kg and 0.2-3.0 μg/kg, respectively. Furthermore, the results indicated that the average recoveries of the 11 sulfonamides ranged from 79.3% to 105.5% at three spiked levels of 50, 100, and 200 μg/kg, with the relative standard deviations (RSDs) in the range of 1.3%-11.6% (n=6). This method showed higher extraction efficiency than the one-step liquid-liquid extraction, and the detection sensitivity was highly improved.

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Rapid simultaneous determination of 10 nutrients in ginger by ultra-high performance liquid chromatography-tandem mass spectrometry ZHANG Wenhuan, LIU Pingxiang, QIU Jing, JIA Qi, QIAN Yongzhong 2019, 37 (10):  1105-1111.  DOI: 10.3724/SP.J.1123.2019.03024 Abstract ( 158 )   [Full Text(HTML)] () PDF (1096KB) ( 177 )   An analytical method by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for the simultaneous determination of the two types of nutrients, viz. gingerol-related compounds and curcuminoids in ginger, including 6-gingerol, 8-gingerol, 10-gingerol, 6-shogaol, 8-shogaol, 10-shogaol, tetrahydrocurcumin, curcumin, demethoxycurcumin and bisdemethoxycurcumin. The 10 target compounds were separated on a ZORBAX RRHD Eclipse Plus C18 column (100 mm×2.1 mm, 1.8 μm) using gradient elution with 0.1% (v/v) formic acid aqueous solution and methanol containing 0.1% (v/v) formic acid as the mobile phases. Qualitative confirmation and quantitative analysis of the target compounds were performed using an electrospray ionization (ESI) source in the positive ion and multiple reaction monitoring (MRM) modes. The linear correlation coefficients (r) of the 10 nutrients were ≥ 0.9995. The limits of quantification were 0.10-7.71 μg/L. The average spiked recoveries of the samples at the three levels were 82.8%-115.3%, the relative standard deviations (RSDs) were 0.58%-11.49%. The results showed that all the 10 nutrients in ginger were detected, and the content of 6-gingerol was the highest at 373.35-702.48 mg/kg. This method is convenient, rapid, accurate and reliable, and is suitable for the analysis of gingerol-related and curcuminoids in ginger. It provides a technical means for the quality identification and control of ginger.

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Determination of benzimidazoles residue markers in chicken tissue by high performance liquid chromatography ZOU You, SHAO Linzhi, WU Yingxuan 2019, 37 (10):  1112-1117.  DOI: 10.3724/SP.J.1123.2019.03031 Abstract ( 60 )   [Full Text(HTML)] () PDF (855KB) ( 50 )   A method was developed for the simultaneous determination of 11 benzimildazoles residue markers in chicken meat, liver and kidney samples by high performance liquid chromatography (HPLC). The chicken tissue sample was extracted with acetonitrile, defatted with n-hexane, and purified with an MCX solid-phase extraction cartridge. Chromatographic separation was performed on an Atlantis T3 column with the gradient elution of methyl alcohol-1% (v/v) acetic acid aqueous solution as the mobile phases at a flow rate of 1.0 mL/min. The detection wavelength was set at 292 nm. Analytes were quantified by the external standard method. The linearities of the calibration curves were well in the range of 25-1000 μg/L, and the limit of quantification was 50 μg/kg. The recoveries at different spiked levels in all the three matrices ranged from 70.91% to 103.21%, and the relative standard deviations (RSDs) were between 1.48% and 10.08% (n=6). The developed method is characterized by an excellent purification effect, sensitivity and accuracy, and can be used for the determination of benzimidazoles residue markers in chicken tissue samples.

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Determination of N,N'-ethylenediamine disuccinic acid in bioconversion reaction solution using high performance liquid chromatography WU Zhichao, WU Enguo, YANG Zhongyi, TAO Yuxiang, CHEN Tan, ZHONG Yongjun 2019, 37 (10):  1118-1123.  DOI: 10.3724/SP.J.1123.2019.03033 Abstract ( 95 )   [Full Text(HTML)] () PDF (1024KB) ( 78 )   A method was developed for the determination of N,N'-ethylenediamine disuccinic acid (EDDS) in bioconversion samples by high performance liquid chromatography (HPLC). An InertSustain AQ-C18 column (250 mm×4.6 mm, 5 μm) was used in the analysis. The mobile phase was 25% (v/v) methanol with 1.0 g/L Cu(CO2CH3)2·H2O, 2.0 g/L tetrabutylammonium hydroxide, and the pH was adjusted to 2.80 with phosphoric acid. The flow rate of the mobile phase was 1.0 mL/min, and the column temperature was set at 30℃. The detection wavelength was 254 nm. EDDS, fumaric acid, citric acid, malic acid and ethylenediaminetetraacetic acid (EDTA) were separated from one another within 8 min. EDDS showed good linearity in the range of 0.06-0.6 g/L. About 0.25 g/L EDDS was detected in the biosynthesis reaction solution catalyzed by recombinant EDDS-lyase, while 36.56 g/L malic acid was formed as the by-product from fumaric acid. The catalytic activity of the enzyme was confirmed in the hydrolysis of 10 g/L EDDS, which produced 3.05 g/L malic acid in 3 h. This analytical method is simple, rapid, sensitive, reliable, and suitable for the analysis in the research of EDDS bioconversion process.

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Rapid determination of ammonia nitrogen in sewage by headspace gas chromatography PENG Rong, LIU Hao, CHAI Xinsheng, JIANG Ran 2019, 37 (10):  1124-1128.  DOI: 10.3724/SP.J.1123.2019.03001 Abstract ( 119 )   [Full Text(HTML)] () PDF (841KB) ( 94 )   This paper reports a novel method for the rapid determination of ammonia nitrogen in sewage by headspace gas chromatography (HS-GC) through a chemical reaction. During the experiment, formaldehyde, initially in excess, was reacted with NH4+ in a headspace bottle to produce a strong acid with equal molarity. Thereafter, NaHCO3 was reacted with the newly generated acid to produce CO2. In the final step, the released CO2 was determined using a gas chromatograph equipped with a thermal conductivity detector. Good linear correlation between the ammonia nitrogen content and the gas chromatographic signals was achieved. The observed correlation coefficient was 0.999, and the limit of quantification (LOQ) was 0.786 mg/L (measured based on the mass concentration of N). The relative standard deviation of reproducibility was less than 2%, and the standard recovery was between 95% and 105%. Compared with Nassar's reagent method, the relative deviation of this method is within ±5%. This method has high detection efficiency and is suitable for the rapid batch detection of ammonia nitrogen in sewage.

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Determination and classification of flammable liquids by headspace gas chromatography-mass spectrometry HE Jiangang, WAN Wangjun, WU Gang, WANG Chen, ZHU Jing, YUAN Conghui 2019, 37 (10):  1129-1133.  DOI: 10.3724/SP.J.1123.2019.03018 Abstract ( 63 )   [Full Text(HTML)] () PDF (851KB) ( 53 )   An effective method was established for the determination and classification of flammable liquids by headspace gas chromatography-mass spectrometry (HS-GC-MS). The volatile components, equilibrium temperature and equilibrium time of gravure ink were investigated. The volatile components of flammable liquids were identified by comparison with the standard mass spectrum databases, and quantified by the external standard method. The recoveries were in the range of 92.8%-103.1% with the relative standard deviations between 0.88% and 2.88%. The flash points of the samples were calculated by a prediction model and compared with the experimentally measured values. The results showed that the maximum deviation between the predicted and measured flash points was 3.2℃. This method provides a novel, efficient and convenient way for the classification of flammable liquids.