Chinese Journal of Chromatography

Hydrogen isotopes analysis by gas chromatography using metal-organic framework CPL-1 packed column

HU Peng, CHEN Ping, CAO Dawei, FU Xiaolong, XIAO Chengjian, WANG Heyi

2017, 35 (10): 1023-1027. DOI: 10.3724/SP.J.1123.2017.07014

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CPL-1 is a metal organic framework (MOF) with potential application as stationary phase material in gas chromatographic (GC) analysis, due to its large specific surface area, uniform pore size and good quantum sieving effect on hydrogen isotopes at low temperatures. Herein, a microporous column packed with CPL-1 was used at cryogenic temperature (77 K), and the column was 1.0 mm in inner diameter, 0.5 m in length. Single crystals of Al₂O₃ was used to build flow path for chromatographic carrier gas. The results showed that the adsorption of H₂ and D₂ with CPL-1 was 4 mmol/g at 77 K, which was better than MnCl₂/γ -Al₂O₃ and γ -Al₂O₃. With the injection volume increasing from 0.25 mL to 2 mL, the results showed good linear relationship, and the relative error was less than 4%. The results indicated that the column packed with CPL-1 has wide linear range, good repeatability and high accuracy, and it has potential use in hydrogen isotope analysis with gas chromatography.

Comparison of CIM^® C4-HLD monolithic column with Sartobind phenyl membrane column for pIDKE2 purification

Miladys LIMONTA, Lourdes ZUMALACÁRREGUI, Urska VIDIC, Nika LENDERO KRAJNC

2017, 35 (10): 1028-1036. DOI: 10.3724/SP.J.1123.2017.05005

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The main component of the Center for Genetic Engineering and Biotechnology (CIGB) candidate vaccine against Hepatitis C virus (HCV) is the pIDKE2 plasmid.The current designed downstream process for the production of pIDKE2 fulfils all regulatory requirements and renders the required quantities of pharmaceutical-grade plasmid DNA (pDNA) with 95% purity.The advantages of this procedure include high plasmid purity and the elimination of undesirable additives,such as toxic organic extractants and animal-derived enzymes.However,yields and consequently the productivity of the process are low.Previous work demonstrated that the most critical step of the process is the reverse phase chromatography,where conventional porous particle resins are used.Therefore,to increase the process productivity,alternative technologies such as membranes and chromatographic monoliths were tested as alternative options for this critical step.Here,a comparison between the behaviors of CIM^® C4-HLD and Sartobind phenyl matrices was performed.To obtain higher productivities and purities,the dynamic binding capacities and selectivities were evaluated.The results showed that both matrices had a similar capacity for pIDKE2 plasmid,but the separation of pDNA isoforms using CIM technology was much better than that with Sartobind.Additionally,the optimal conditions for loading plasmid DNA on a CIM^® C4-HLD 800-mL monolithic column in a real production process were determined.These optimizations will allow production levels to satisfy the high plasmid consumption demanded by clinical trials.

High-sensitive detection of multiple allergenic proteins in infant food with high-resolution mass spectrometry

WU Ci, CHEN Xi, LIU Jianhui, ZHANG Xiaolin, XUE Weifeng, LIANG Zhen, LIU Mengyao, CUI Yan, HUANG Daliang, ZHANG Lihua

2017, 35 (10): 1037-1041. DOI: 10.3724/SP.J.1123.2017.06013

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A novel method of the simultaneous detection of multiple kinds of allergenic proteins in infant food with parallel reaction monitoring (PRM) mode using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established. In this method, unique peptides with good stability and high sensibility were used to quantify the corresponding allergenic proteins. Furthermore, multiple kinds of allergenic proteins are inspected simultaneously with high sensitivity. In addition, such method was successfully used for the detection of multiple allergenic proteins in infant food. As for the sample preparation for infant food, compared with the traditional acetone precipitation strategy, the protein extraction efficiency and capacity of resisting disturbance are both higher with in-situ filter-aided sample pretreatment (i-FASP) method. All allergenic proteins gave a good linear response with the correlation coefficients (R²) ≥ 0.99, and the largest concentration range of the allergenic proteins could be four orders of magnitude, and the lowest detection limit was 0.028 mg/L, which was better than that reported in references. Finally, the method was conveniently used to detect the allergens from four imported infant food real samples. All the results demonstrate that this novel strategy is of great significance for providing a rapid and reliable analytical technique for allergen proteomics.

Determination of urine catecholamines and metanephrines by reversed-phase liquid chromatography-tandem mass spectrometry

CHEUK Man-Yung, LO Yun-Chuen, POON Wing-Tat

2017, 35 (10): 1042-1047. DOI: 10.3724/SP.J.1123.2017.06011

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The measurement of urine catecholamine and metanephrine concentrations is important for biochemical screening and diagnosis of pheochromocytoma. The goal of this work was to develop a simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determining catecholamines and metanephrines in urine to replace an existing liquid chromatographic method using electrochemical detection. Urine samples were prepared using Oasis weak-cation-exchange cartridges. The eluate was analyzed on an Agilent ZORBAX Eclipse Plus Phenyl-Hexyl column in 3 min. Adrenaline, noradrenaline, dopamine, metanephrine, normetanephrine, and their deuterated internal standards were monitored in positive electrospray ionization mode by multiple reaction monitoring (MRM). No evidence of ion suppression was observed. The assay was linear up to 5μmol/L for adrenaline, 5μmol/L for noradrenaline, 6.1μmol/L for dopamine, 5.6μmol/L for metanephrine, and 34.6μmol/L for normetanephrine, with lower limits of quantification of 5, 5, 12, 6 and 7 nmol/L, respectively. The intra-day and inter-day precisions for all analytes ranged from 0.59% to 4.64% and 1.98% to 4.80%, respectively. External quality assurance samples were assayed and showed excellent agreement with the target values. This simple method provides an improved assay for determining urine catecholamines and metanephrines.

Determination of thyreostats in bovine urine using ultra-high performance liquid chromatography-tandem mass spectrometry

Lech RODZIEWICZ, Jolanta MASŁOWIECKA, Anna SADOWSKA, Halina CAR

2017, 35 (10): 1048-1054. DOI: 10.3724/SP.J.1123.2017.05004

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Five thyreostats (TSs), namely tapazole, thiouracil, methylthiouracil, propylthiouracil, and phenylthiouracil, were determined in bovine urine using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in positive electrospray ionization mode. Extraction and clean-up were achieved using a ChemElut cartridge with tert-butyl methyl ether, without a derivatization step. Separation was achieved on an Acquity UPLC SS T3 column. The mobile phase was acetonitrile and water containing 0.2% (v/v) formic acid. The mass spectrometer was operated in multiple reaction monitoring mode. Urine samples were spiked with TS solution at levels corresponding to 5, 10, 15, and 20 μg/L. The accuracy (internal standard corrected) ranged from 92% to 107%, with a repeatability precision (relative standard deviation, RSD) less than 15% for all five analytes. The RSDs within-laboratory reproducibility was less than 26%. The decision limits (CCα) and detection capabilities (CCβ) were obtained from a calibration curve and were in the ranges of 3.1-6.1 μg/L and 4.0-7.4 μg/L, respectively. The CCα and CCβ values were below the recommended concentration, which was set at 10 μg/L. The results show that the described method is suitable for the direct detection of TSs in bovine urine. This method can also be used to determine TSs in porcine urine.

Liquid chromatography-tandem mass spectrometry method for determination of 10 macrolide antibiotics in pork samples using on-line solid phase extraction purification

ZHANG Xiaoguang, LIU Dong, LIU Hongran, LI Qiang, LI Lili, WANG Lixia, ZHANG Yan

2017, 35 (10): 1055-1061. DOI: 10.3724/SP.J.1123.2017.04004

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A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method based on-line solid phase extraction (SPE) purification was established to determine 10 macrolide antibiotics in pork samples. The samples were extracted with acetonitrile, and the extracts were dried with rotary evaporator at 40℃, then the analytes were dissolved with 2 mL phosphate buffer. The solutions were purified and concentrated by on-line SPE with HLB cartridges. The analytes were eluted with methanol, and then transferred to XBridge BEH C18 column, separated with the mobile phases of 10 mmol/L ammonium acetate aqueous solution and acetonitrile. Finally, the target analytes were detected by tandem mass spectrometry. The results showed that good linearity was obtained in the range of 0.1-200 μg/L for the 10 macrolide antibiotics with correlation coefficients better than 0.990. The limits of detection were in range of 0.05-0.30 μg/kg and the limits of quantitation were in range of 0.10-1.00 μg/kg. The recoveries of the method were in range of 69.6%-115.2% at the spiked levels of 0.10-10.0 μg/kg for all analytes, with the relative standard deviations less than 10%. The developed method can be used for the determination of the 10 macrolide antibiotics in pork samples.

Determination of imidazoles and their metabolites in pork by liquid chromatography-tandem mass spectrometry

YANG Wanghuo, WU Shaoming, CAI Xiaoming, FENG Lifeng, CHEN Yankai, LI Yanping, LIANG Min

2017, 35 (10): 1062-1067. DOI: 10.3724/SP.J.1123.2017.06029

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A method for the determination of 29 imidazoles and their metabolites in pork by liquid chromatography-tandem mass spectrometry has been developed. The samples were extracted with ethyl acetate, and then defatted with n-hexane after concentration of the extracts. The analytes were separated on a C₁₈ reversed-phase column with 0.3% (v/v) formic acid aqueous solution and acetonitrile as mobile phases, and finally analyzed using electrospray ionization in positive ion mode (ESI⁺) with multiple reaction monitoring (MRM). The linear ranges of the 29 compounds were from 0.05 to 20.0 μg/L with the correlation coefficients (r²) more than 0.99. The average recoveries and relative standard deviations were 65.4%-103% and 1.3%-6.8% respectively in the spiked ranges of 1.0-5.0 μg/kg. The limits of detection and the limits of quantification were 0.02-0.3 μg/kg and 0.1-1 μg/kg respectively for the 29 imidazoles. The method is simple, rapid and sensitive. It is suitable for the detection of imidazoles and their metabolites in pork.

Determination of characteristic compound in manuka honey by automatic on-line solid phase extraction-liquid chromatography-high resolution mass spectrometry

SHEN Chongyu, GUO Siyan, DING Tao, LIU Yun, CHEN Lei, FEI Xiaoqing, ZHANG Rui, WU Bin, SHEN Weijian, CHEN Lei, ZHANG Feng, FENG Feng, DENG Xiaojun, YI Xionghai, YANG Gongjun, CHEN Guoqiang

2017, 35 (10): 1068-1072. DOI: 10.3724/SP.J.1123.2017.07009

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A method for the determination of characteristic compound 3,5-dimethoxybenzoate-4-diglucoside (leptosperin) in manuka honey was developed by automatic on-line solid phase extraction-liquid chromatography-high resolution mass spectrometry (SPE-LC-HRMS). The samples were separated on a Dikma Diamonsil Plus C₁₈ column (150 mm×4.6 mm, 5 μm) using the mobile phases of 0.1% (v/v) formic acid aqueous solution and acetonitrile with gradient elution. The compound was detected with negative electrospray ionization (ESI^-) in Target-MS² mode. The results showed that the linear range was 0.5-100.0 mg/L, the correlation coefficient was 0.9993. The limit of detection (LOD, S/N ≥ 3) and limit of quantification (LOQ, S/N ≥ 10) of the method was 3 mg/kg and 10 mg/kg, respectively. The recoveries at the spiked levels of 50.0, 100.0, 200.0 mg/kg (10.0, 20.0, 50.0 mg/kg in black locust samples) were in the range of 82.0%-95.2% with the relative standard deviations ranging from 2.7% to 9.7% (n=6). The proposed method was applied to 95 mature honey samples from hives in New Zealand including 12 different kinds and 50 commercial honey samples from four different countries. The method is fast, sensitive and accurate to provide technical support to solve the judgment of the manuka honey imported from New Zealand.

Simultaneous determination of nine perfluorinated compound precursors in atmospheric precipitation by solid phase extraction and ultra performance liquid chromatography with tandem mass spectrometry

ZHANG Ming, TANG Fangliang, XU Jianfen, YU Bo, ZHANG Wei, YAO Jianliang, HU Minhua

2017, 35 (10): 1073-1079. DOI: 10.3724/SP.J.1123.2017.06025

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A high-throughput detection method has been developed for the determination of nine perfluorinated compound precursors (PFCPs) in atmospheric precipitation by solid phase extraction-ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (SPE-UPLC-ESI-MS/MS). The atmospheric precipitation samples were concentrated and purified with HLB solid phase extraction cartridges. The UPLC separation was performed on an HSS T₃ column (100 mm×2.1 mm, 1.7 μm) utilizing a gradient elution program of methanol and water as the mobile phases at a flow rate of 0.2 mL/min. The MS/MS detection was performed under negative electrospray ionization (ESI^-) in multiple reaction monitoring (MRM) mode. Good linearity was observed in the range of 0.05-5.00 μg/L, 0.50-50.0 μg/L or 5.00-500 μg/L with correlation coefficients from 0.9921 to 0.9995. The limits of detection (LODs) for the nine perfluorinated compound precursors were in the ranges of 0.05-7.9 ng/L. The recoveries ranged from 76.0% to 106% with the relative standard deviations between 0.72% and 13.7%. This method is characterized by high sensitivity and precision, extensive analytical range and quick analytical rate, and can be applied for the analysis of perfluorinated compound precursors in atmospheric precipitation.

Determination of hexabromocyclododecanes in ambient air by high performance liquid chromatography- electrospray ionization-mass spectrometry

LI Yan, WANG Longxing, ZHU Xiuhua, GAO Yuan, CHEN Jiping

2017, 35 (10): 1080-1085. DOI: 10.3724/SP.J.1123.2017.06026

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A high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) method was developed for the determination of hexabromocyclododecanes (HBCDs) in ambient air samples. The samples were extracted by Soxhlet extractor with hexane, then purified on the composite gel column. At first, the interfering substances were rinsed with 50 mL hexane and 100 mL hexane-dichloromethane (9:1, v/v), then 180 mL hexane -dichloromethane (4:1, v/v) was used to elute the targets. The compounds were separated by gradient elution with acetonitrile-methanol-water as mobile phases on a UF-ODS column (150 mm×2.1 mm, 3.0 μm). Electrospray ionization negative ion source and selective ion monitoring (SIM) mode were adopted in MS detection. The results showed that α -HBCD, β -HBCD and γ -HBCD could be well separated, and the chromatographic peak area ratio of α -HBCD, β -HBCD and γ -HBCD to internal standard D₁₈- γ -HBCD with their concentrations had a good linear relationship, with the correlation coefficients (R) ≥ 0.9988. The limits of detection (LODs, S/N=3) of α -HBCD, β -HBCD and γ -HBCD were 0.4, 0.5 and 0.4 μg/L, respectively. The limits of quantification (LOQs, S/N=10) were 1.4, 1.6 and 1.3 μg/L, respectively. The method detection limits (MDL) were 0.13, 0.17 and 0.13 pg/m³ (n=5), respectively. The recoveries of HBCDs spiked in the actual air samples were in the range of 74.8%-95.8%. It is demonstrated that the method has high sensitivity and good selectivity, and can meet the requirement of monitoring and analyzing HBCDs in air samples.

Rapid determination of 10 volatile N-nitrosamines in sour meats by modified QuEChERS and gas chromatography- triple quadrupole mass spectrometry

ZHAO Zhuang, XU Yangbiao, LIU Xianghong, SHI Xiaoguang, LU Yixiang

2017, 35 (10): 1086-1093. DOI: 10.3724/SP.J.1123.2017.06006

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A rapid gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) method with modified QuEChERS method was developed for the determination of 10 volatile N-nitrosamines in sour meats. The samples were extracted with acetonitrile and eliminated the fat with n-hexane. The extracts in acetonitrile layer were purified by octadecyl silane (C18) and primary secondary amine (PSA) sorbents. The N-nitrosamines were determined on a DB-WAX column (30 m×0.25 mm×0.25 μm) by GC-MS/MS in selected reaction monitoring (SRM) mode. The external standard method was used to quantify the N-nitrosamines. The correlation coefficients (r) of the standard calibration curves were greater than 0.99 in the range of 1-100 μg/L. The average recoveries ranged from 79.8% to 115.3% with the relative standard deviations (RSDs) from 0.6% to 22.9% (n=6). The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) were 0.04-0.3 μg/kg and 0.1-1 μg/kg, respectively. The developed method is simple, rapid, sensitive and efficient for the screening of the N-nitrosamines in sour meats.

Target and non-target screening of volatile organic compounds in industrial exhaust gas using thermal desorption-gas chromatography-mass spectrometry

MA Huilian, JIN Jing, LI Yun, CHEN Jiping

2017, 35 (10): 1094-1099. DOI: 10.3724/SP.J.1123.2017.06023

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A method of comprehensive screening of the target and non-target volatile organic compounds (VOCs) in industrial exhaust gas using thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed. In this paper, two types of solid phase adsorption column were compared, and the Tenex SS TD Tube was selected. The analytes were enriched into the adsorption tube by constant flow sampling, and detected by TD-GC-MS in full scan mode. Target compounds were quantified by internal standard method, and the quantities of non-target compounds were calculated by response coefficient of toluene. The method detection limits (MDLs) for the 24 VOCs were 1.06 to 5.44 ng, and MDLs could also be expressed as 0.004 to 0.018 mg/m³ assuming that the sampling volume was 300 mL. The average recoveries were in the range of 78.4% to 89.4% with the relative standard deviations (RSDs) of 3.9% to 14.4% (n=7). The established analytical method was applied for the comprehensive screening of VOCs in a waste incineration power plant in Dalian city. Twenty-nine VOCs were identified. In these compounds, only five VOCs were the target compounds set in advance, which accounted for 26.7% of the total VOCs identified. Therefore, this study further proved the importance of screening non-target compounds in the analysis of VOCs in industrial exhaust gas, and has certain reference significance for the complete determination of VOCs distribution.

Determination of guanidinoacetic acid in feed by ion chromatography coupled with ultraviolet detection

SUN Xiangli, WEI Yanyan, LIU Weiguo, ZHANG Liying

2017, 35 (10): 1100-1104. DOI: 10.3724/SP.J.1123.2017.06016

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A novel ion chromatography method for the determination of guanidinoacetic acid (GAA) in animal feed samples was developed. The optimal detection mode, chromatography column, gradient condition of mobile phases and sample pretreatment conditions were investigated. Using a linear gradient of methane sulfonic acid and ultraviolet detector at 200 nm, the interfering substances in feed samples and GAA could be separated successfully on a Dionex IonPac^TM CS16 cation exchange analysis column. The calibration curves showed a range of linearity between 0.5 and 200 mg/L, and a high linear regression coefficient of 0.9999 was obtained for GAA. The limits of detection and limits of quantification of GAA in formula feed and concentrate feed were 4.5 and 15 mg/kg, respectively. The limit of detection and limit of quantification of GAA in compound-premix were 9.0 and 30 mg/kg, respectively. The recoveries of this method for GAA were investigated, and the recoveries were all more than 94% in formula feed, concentrate feed and compound-premix feed for pig and poultry. This method can meet the requirements of the determination of GAA in feed samples for the feed production enterprise and evaluation center.

Simultaneous determination of 15 polycyclic aromatic hydrocarbons in cigarette filter by gas chromatography-tandem mass spectrometry

ZHANG Xiaotao, ZHANG Li, RUAN Yibin, WANG Weiwei, JI Houwei, WAN Qiang, LIN Fucheng, LIU Jian

2017, 35 (10): 1105-1110. DOI: 10.3724/SP.J.1123.2017.06020

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A method for the simultaneous determination of 15 polycyclic aromatic hydrocarbons in cigarette filter was developed by isotope internal standard combined with gas chromatography-tandem mass spectrometry. The cigarette filters were extracted with dichloromethane, and the extract was filtered with 0.22 μm organic phase membrane. The samples were isolated by DB-5MS column (30 m×0.25 mm, 0.25 μm) and detected using multiple reaction monitoring mode of electron impact source under positive ion mode. The linearities of the 15 polycyclic aromatic hydrocarbons (acenapthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, ben[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene and indeno[1,2,3-c,d]pyrene) were good, and the correlation coefficients (R²) ranged from 0.9914 to 0.9999. The average recoveries of the 15 polycyclic aromatic hydrocarbons were 81.6%-109.6% at low, middle and high spiked levels, and the relative standard deviations were less than 16%, except that the relative standard deviation of fluorene at the low spiked level was 19.2%. The limits of detection of the 15 polycyclic aromatic hydrocarbons were 0.02 to 0.24 ng/filter, and the limits of quantification were 0.04 to 0.80 ng/filter. The method is simple, rapid, accurate, sensitive and reproducible. It is suitable for the quantitative analysis of the 15 polycyclic aromatic hydrocarbons in cigarette filters.

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