Chinese Journal of Chromatography

Determination of five imidazole pesticide residues in fruits by Turbo flow online purification-ultra performance liquid chromatography-tandem mass spectrometry

ZHANG Lu, KONG Xianghong, HE Qiang, ZHANG Longzhuang, LI Jianhua

2014, 32 (6): 559-565. DOI: 10.3724/SP.J.1123.2014.02001

Abstract ( 712 ) [Full Text(HTML)] ()

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A Turbo flow-ultra performance liquid chromatography-tandem mass spectrometry (TF-UPLC-MS/MS) method was developed for the determination of five imidazole pesticides (imazapyr, triazoxide, rabenzazole, prochloraz and fenamidone) in fruits. The fruit samples were dissolved in saturated sodium chloride solution and extracted by acetonitrile. After the acetonitrile layer was evaporated and redissolved with acetonitrile-water (1:1, v/v), the fruit samples were analyzed by TF-UPLC-MS/MS. The main factors influencing the purification efficiency including the TF column, mobile phase, elution solution and elution rate were optimized. Under the optimized experimental conditions, the analytes were purified by Turbo flow C18 column (50 mm×1.0 mm) and separated on a Hypersil GOLD aQ column (100 mm×2.1 mm) using the mobile phases of acetonitrile and 5 mmol/L ammonium acetate (containing 0.1% (v/v) formic acid) aqueous solution with gradient elution. The compounds were detected by selective reaction monitoring (SRM) via positive electrospray ionization (ESI⁺). The linear range of the method ranged from 0.0075 to 0.75 mg/L for all the five imidazole pesticides, with the correlation coefficients (r²) greater than 0.99. The limits of quantification were 0.005 mg/kg for all the five imidazole pesticides. The recoveries were in the range from 71.2% to 122.4% at the spiked levels of 0.005, 0.01, 0.05 and 0.5 mg/kg with the relative standard deviations ranging from 0.5% to 8.9% in actual samples. The results indicate that the developed method is simple, efficient and precise, and can be a reliable technique for the determination of the five imidazole pesticides in fruit samples.

Determination of streptomycin and dihydrostreptomycin in pollens by high performance liquid chromatography-tandem mass spectrometry

HUANG Juan, YIN Yao, XU Jinzhong, LIU Yan, CHEN Guosong, ZHANG Xiaoyan, YANG Wenquan, SHENG Chongyu, CHEN Huilan, ZHANG Rui

2014, 32 (6): 566-572. DOI: 10.3724/SP.J.1123.2014.02009

Abstract ( 856 ) [Full Text(HTML)] ()

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A method was established for the determination of streptomycin (STR) and dihydrostreptomycin (DHS) in pollens based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted and cleaned-up by a C18 solid phase extraction cartridge. The separation was carried out on a Protemix WCX-NP5 column (100 mm×2.1 mm, 5 μm) with a gradient elution using 5% (v/v) formic acid, 20 mmol/L ammonium acetate and methanol as mobile phases. The analysis of streptomycin and dihydrostreptomycin was performed under electrospray positive ionization mode. The limits of detection (LOD, S/N=3) and limits of quantification (LOQ, S/N=10) for the both were 5 μg/kg and 10 μg/kg, respectively. Good linearities (r >0.99) were achieved for the target compounds over the range of 10-200 μg/L. The recoveries at three spiked levels (10, 20, 50 μg/kg) in the blank matrices, such as pollen pini, corn pollen, camellia pollen, sunflower pollen, rape pollen and bee pollen, were from 76.8% to 100.3% with the relative standard deviations varied from 3.70% to 12.6%. The method is accurate, practical, and can be applied to most of the contaminated matrices. With this method, heptafluorobutyric acid is not required as mobile phase which is harmful to MS spectrometer.

Simultaneous determination of nine β-blockers in porcine tissues by ultra-fast liquid chromatography coupled with quadrupole/linear ion trap mass spectrometry

ZHANG Hongwei, XU Hui, GAO Jianguo, LIANG Chengzhu, XU Biao, GENG Juan, WANG Fengmei, ZHANG Xiaomei, CHENG Gang

2014, 32 (6): 573-581. DOI: 10.3724/SP.J.1123.2014.02014

Abstract ( 733 ) [Full Text(HTML)] ()

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A highly sensitive method using ultra-fast liquid chromatography coupled with quadrupole/linear ion trap mass spectrometry (UFLC-Q/Trap MS) was developed to simultaneously screen and confirm nine β-blockers (BBs) in porcine tissues (porcine muscle, liver and kidney). The method was used for trace determination of atenolol, pindolol, acebutolol, metoprolol, carazolol, labetalol, bisoprolol, propranolol and penbutolol. The homogenized tissues were hydrolyzed by β-glucuronidase/aryl sulfatase and extracted with acetonitrile, followed by continuous purification procedures of disperse solid phase extraction (d-SPE) with diatomaceous earth and BondElut cartridge. The ultra-fast chromatographic separation was conducted on a Kinetex^TM C18-XB column (150 mm×2.1 mm, 2.6 μm) using 0.1% (v/v) formic acid aqueous solution and methanol as mobile phases in gradient elution. The optimized ion transitions were employed in the mixed-mode of scheduled multiple reaction monitoring (sMRM)-information dependent acquisition (IDA)-enhanced product ion (EPI) scan. Qualification analysis was performed through spectra-matching with on-line lab-built MS/MS library. For quantification stable isotope-labelled analogues of the analytes were used as internal standards. As a result, in porcine liver, kidney and muscle, the nine BBs showed good linearity with all the correlation coefficients (r) more than 0.995 in the range of 0.1-20 μg/L. The limits of quantification (LOQ, S/N≥10) were 0.5 μg/kg for all the analytes. The developed method gave average recoveries of 87.5%-111.8% spiked at 0.5, 1.0 and 5.0 μg/kg with the relative standard deviations of 4.0%-12.5%. The proposed method can be used to screen and confirm the nine BBs in a single run, which makes it effective in surveillance and detection of the BBs residues in porcine tissues.

Determination of gossypol in edible vegetable oil with high performance liquid chromatography-tandem mass spectrometry

ZHANG Wenhua, HUANG Chaoqun, XIE Wen, SHEN Li

2014, 32 (6): 582-585. DOI: 10.3724/SP.J.1123.2014.02029

Abstract ( 1201 ) [Full Text(HTML)] ()

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A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of gossypol in edible vegetable oil. The sample was extracted with ethyl alcohol by vortex-excited oscillation. The extract was cleaned up by 0.22 μm filter membrane and centrifuged for 5 min at 4 000 r/min after standing in a fridge at 4 ℃ for 30 min. The compound was separated on a C18 column (100 mm×2.1 mm, 3.5 μm) with acetonitrile and 1% (v/v) formic acid aqueous solution as mobile phase. The detection of gossypol was carried out by LC-MS/MS with positive electrospray ionization under multiple reaction monitoring (MRM) mode using external standard method. The limits of quantification (S/N>10) of gossypol in edible vegetable oil was 1 mg/kg. The recoveries were from 87.4% to 100% at the spiked levels of 1, 2, 200 mg/kg of gossypol in edible vegetable oil with the relative standard deviations (RSDs) between 3.9% and 12.2%. The method, with high sensitivity, good precision and high recovery, was suitable for the confirmation and quantification of gossypol residue in edible vegetable oil.

Determination of α-solanine,α-chaconine and solanidine in plasma and urine by ultra-performance liquid chromatography-triple quadrupole mass spectrometry

ZHANG Xiuyao, CAI Xinxin, ZHANG Xiaoyi

2014, 32 (6): 586-590. DOI: 10.3724/SP.J.1123.2014.03001

Abstract ( 1047 ) [Full Text(HTML)] ()

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An ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS) method was developed for the determination of α-solanine,α-chaconine and solanidine in plasma and urine. The sample was acidified with aqueous solution containing 2% (v/v if not specified) formic acid, and then cleaned-up by solid-phase extraction with a mixed-mode cation exchange (MCX) cartridge. The analysis of the glycoalkaloids was carried out on an Acquity UPLC BEH C₁₈ column (50 mm×2.1 mm, 1.7 μm) with gradient elution of acetonitrile (containing 0.1% formic acid) and H₂O (containing 0.05% formic acid and 5.0 mmol/L ammonium acetate). The analytes were detected by positive electrospray ionization tandem mass spectrometry in MRM mode, and quantified by external matrix-matched standard calibration. The cycle time of each analysis was 5.5 min. The calibration curves were linear in the range of 0.3-100 ng/mL of the glycoalkaloids in plasma and urine. The correlation coefficients were 0.997-0.999. The limits of detection (S/N=3) and quantitation (S/N=10) were 0.1 ng/mL and 0.3 ng/mL. The average recoveries were 82%-112% and 96%-114% for the glycoalkaloids spiked in plasma and urine, respectively, with relative standard deviations of 4.0%-16% and 2.7%-17% (n=6). The method is simple, accurate and sensitive to detect the glycoalkaloids in plasma and urine for both clinical and forensic purposes.

Qualitative and quantitative analysis of amygdalin and its metabolite prunasin in plasma by ultra-high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry and ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry

GAO Meng, WANG Yuesheng, WEI Huizhen, OUYANG Hui, HE Mingzhen, ZENG Lianqing, SHEN Fengyun, GUO Qiang, RAO Yi

2014, 32 (6): 591-599. DOI: 10.3724/SP.J.1123.2014.01021

Abstract ( 963 ) [Full Text(HTML)] ()

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A method was developed for the determination of amygdalin and its metabolite prunasin in rat plasma after intragastric administration of Maxing shigan decoction. The analytes were identified by ultra-high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry and quantitatively determined by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry. After purified by liquid-liquid extraction, the qualitative analysis of amygdalin and prunasin in the plasma sample was performed on a Shim-pack XR-ODS Ⅲ HPLC column(75 mm×2.0 mm, 1.6 μm), using acetonitrile-0.1% (v/v) formic acid aqueous solution. The detection was performed on a Triple TOF 5600 quadrupole time of flight mass spectrometer. The quantitative analysis of amygdalin and prunasin in the plasma sample was performed by separation on an Agilent C₁₈ HPLC column (50 mm×2.1 mm, 1.7 μm), using acetonitrile-0.1% (v/v) formic acid aqueous solution. The detection was performed on an AB Q-TRAP 4500 triple quadrupole mass spectrometer utilizing electrospray ionization (ESI) interface operated in negative ion mode and multiple-reaction monitoring (MRM) mode. The qualitative analysis results showed that amygdalin and its metabolite prunasin were detected in the plasma sample. The quantitative analysis results showed that the linear range of amygdalin was 1.05-4200 ng/mL with the correlation coefficient of 0.9990 and the linear range of prunasin was 1.25-2490 ng/mL with the correlation coefficient of 0.9970. The method had a good precision with the relative standard deviations (RSDs) lower than 9.20% and the overall recoveries varied from 82.33% to 95.25%. The limits of detection (LODs) of amygdalin and prunasin were 0.50 ng/mL. With good reproducibility, the method is simple, fast and effective for the qualitative and quantitative analysis of the amygdalin and prunasin in plasma sample of rats which were administered by Maxing shigan decoction.

Preliminary study of two steps aqueous two-phase extraction combined with high performance liquid chromatography for saliva protein selective separation

ZHAO Xinying, QU Feng, QIN Hao, LUO Aiqin

2014, 32 (6): 600-603. DOI: 10.3724/SP.J.1123.2014.03031

Abstract ( 644 ) [Full Text(HTML)] ()

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Saliva protein separation by one-step aqueous two-phase extraction (ATPE) in the system of 15% (mass ratio if not specified) PEG-4000/8% NaH₂PO₄ was presented. The proteins extracted from the top and bottom phases were separated and characterized by high performance liquid chromatography (HPLC) respectively. Under the optimized gradient elution procedure, more saliva protein peaks in the two phases were shown. Saliva protein peaks in 50 min gradient were divided into ten specific groups which were classified into six sections based on the protein distribution in the top and bottom phases. Then, the top or bottom phase was performed the second step ATPE. Possible reasons for protein partition and retention difference are discussed briefly. Results show that some proteins can be separated completely in one-step ATPE, while some can be separated in the following two-step ATPE. The combination of two steps ATPE and HPLC provides a new way to achieve selective separation.

Establishment of the mathematical model for the inhibition on α-glycosidase by chemical compositions from Terminalia chebula Retz. based on the liquid chromatographic information

WANG Dingying, ZHU Jingbo, DING Yan, KOU Zinong, YANG Lanping

2014, 32 (6): 604-611. DOI: 10.3724/SP.J.1123.2014.01025

Abstract ( 566 ) [Full Text(HTML)] ()

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The extracts from Chinese herbs are complex compounds with uncertain mechanism, which affects the target with all ingredients. Therefore, it is of great importance to evaluate the bioactivity of these extracts. In this study, 29 samples which had continuous variation of constituents were obtained from the alcohol extract of Terminalia chebula Retz. by a Sephadex LH-20 size exclusion chromatographic column. After detecting the chromatographic information of detection wavelength at 254 nm and the activity information of these samples, the mathematical relationship equation was established to determine the impact on the active components. Stepwise regression method was used to research the relationship between the peak areas (V_i, independent variables) of the compositions in the samples and activities (according to the enzyme inhibition (W), dependent variables). The results showed that there were 55 chromatographic peaks in the samples and the mathematical relationship between the compositions of Terminalia chebula Retz. extract (V_i, i=1, 2,…, 55) and activities was certain. The expression was: W=V₇×(-0.034±0.013)+V₁₈×(-0.155±0.051)+V₂₉×(-0.142±0.028)+V₄×(0.079±0.020)+V₁₁×(0.074±0.028)+V₃₆×(-0.117±0.053)+85.669±4.476, multiple correlation coefficient R=0.854, significance level (Sig. F change)=0.037. The steadiness of model was favorable with new digital information. The compounds corresponding to 18^th, 29^th, 36^th, 4^th, 11^th and 7^th peaks were the main active compounds. The method can be also applied to the relationship between a wide variety of components of traditional Chinese medicine resources and different kinds of activities. It is significant to the research and development of traditional Chinese medicine.

High performance liquid chromatographic enantioseparation of atrolactic acids using chiral mobile phase additive

ZHANG Hu, SHEN Mangmang, TONG Shengqiang, YAN Jizhong

2014, 32 (6): 612-615. DOI: 10.3724/SP.J.1123.2014.02023

Abstract ( 720 ) [Full Text(HTML)] ()

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A method was established for the enantioseparation of atrolactic acids using high performance liquid chromatography with sulfobutyl ether-β-cyclodextrin (SBE-β-CD) as the chiral mobile phase additive, and a C₁₈ reversed-phase column. The influences of the different types of cyclodextrin derivatives, the concentration of chiral mobile phase additive, pH value of the mobile phase, the flow rate and column temperature on the peak resolution were investigated. The separation mechanism for atrolactic acids by high performance liquid chromatography using chiral mobile phase additive, as well as the formation of inclusion complex between SBE-β-CD and atrolactic acid was studied. In addition, the formation constant was calculated. The enantioseparation was carried out on a reversed-phase column YMC-Pack ODS-A C₁₈ (250 mm×4.6 mm, 5 μm) with chiral mobile phase consisted of 0.1 mol/L phosphate buffer at pH 2.68 containing 25 mmol/L SBE-β-CD-acetonitrile (90:10, v/v). The detection wavelength was 220 nm. The flow rate was 0.6 mL/min and the column temperature was 30 ℃. The retention times of atrolactic acids were 26.65 and 28.28 min, and the peak resolution of 1.68 was achieved. The above established method proves to be a simple and economical way for analytical enantioseparation of atrolactic acid with high peak resolution.

Simultaneous determination of migration amounts of antioxidants and ultraviolet absorbents by high performance liquid chromatography in food contact materials

LI Chengfa, LI Ying, CHEN Zhinan, LIANG Feng, CHEN Xuhui, WU Shaojing, LI Yongtao, SUN Xiaoying

2014, 32 (6): 616-622. DOI: 10.3724/SP.J.1123.2014.02010

Abstract ( 769 ) [Full Text(HTML)] ()

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An efficient analytical method for the quantitative determination of migration levels of antioxidants and ultraviolet absorbents in food contact materials by high performance liquid chromatography (HPLC) has been developed. The analytical method showed good linearity with the correlation coefficients (r²) ≥ 0.9998 for all the compounds. The limits of detection were between 0.01 mg/L and 0.22 mg/L and the limits of quantification were in the range of 0.03 to 0.85 mg/L for the 23 analytes. According to the European Union Directive No 10/2011, five food simulants were investigated: 30 g/L acetic acid, 10% (v/v) ethanol, 20% (v/v) ethanol, 50% (v/v) ethanol, and fatty food simulant (isooctane). The recoveries were in the range of 92.8%-117.7%, with the relative standard deviations of 0.95%-9.72%. The effects of different experimental conditions on the recoveries of antioxidants and UV absorbents were studied. The results showed that the method is accurate and stable, and can meet the requirements of European Commission Regulation (EU) No 10/2011 and GB 9685-2008 for the specific migration limits (SML) of the antioxidants and ultraviolet absorbents in real food contact plastic materials and article samples. The method has been applied to determine the migration levels of antioxidants and ultraviolet absorbents in different simulants from the migration tests of 30 batches of food contact material samples.

Determination of four phenolic endocrine disruptors in environmental water samples by high performance liquid chromatography-fluorescence detection using dispersive liquid-liquid microextraction coupled with derivatization

WANG Xiaoyan, QI Weimei, ZHAO Xian'en, LÜ Tao, WANG Xiya, ZHENG Longfang, YAN Yehao, YOU Jinmao

2014, 32 (6): 623-628. DOI: 10.3724/SP.J.1123.2014.02012

Abstract ( 845 ) [Full Text(HTML)] ()

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To achieve accurate, fast and sensitive detection of phenolic endocrine disruptors in small volume of environmental water samples, a method of dispersive liquid-liquid microextraction (DLLME) coupled with fluorescent derivatization was developed for the determination of bisphenol A, nonylphenol, octylphenol and 4-tert-octylphenol in environmental water samples by high performance liquid chromatography-fluorescence detection (HPLC-FLD). The DLLME and derivatization conditions were investigated, and the optimized DLLME conditions for small volume of environmental water samples (pH 4.0) at room temperature were as follows: 70 μL chloroform as extraction solvent, 400 μL acetonitrile as dispersing solvent, vortex mixing for 3 min, and then high-speed centrifugation for 2 min. Using 2-[2-(7H-dibenzo[a,g]carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEC-Cl) as precolumn derivatization reagent, the stable derivatives of the four phenolic endocrine disruptors were obtained in pH 10.5 Na₂CO₃-NaHCO₃ buffer/acetonitrile at 50 ℃ for 3 min, and then separated within 10 min by HPLC-FLD. The limits of detection (LODs) were in the range of 0.9-1.6 ng/L, and the limits of quantification (LOQs) were in the range of 3.8-7.1 ng/L. This method had perfect linearity, precision and recovery results, and showed obvious advantages and practicality comparing to the previously reported methods. It is a convenient and validated method for the routine analysis of phenolic endocrine disruptors in waste water of paper mill, lake water, domestic wastewater, tap water, etc.

Determination of five representative ultraviolet filters in water by gas chromatography-mass spectrometry

DING Yiran, HUANG Yun, ZHAO Tingting, CAI Qian, LUO Yu, HUANG Bin, ZHANG Yuxia, PAN Xuejun

2014, 32 (6): 629-634. DOI: 10.3724/SP.J.1123.2014.01035

Abstract ( 932 ) [Full Text(HTML)] ()

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A method for the determination of five representative organic UV filters: ethylhexyl methoxycinnamate (EHMC), benzophenone-3 (BP-3), 4-methylbenzylidene camphor (4-MBC), octocrylene (OC), homosalate (HMS) in water was investigated. The method was based on derivatization, solid phase extraction (SPE), followed by determination with gas chromatography-mass spectrometry (GC-MS). The variables involved in the derivatization of BP-3 and HMS were optimized, and SPE conditions were studied. For derivatization, 100 μL N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) was used as derivatization reagent and reacted with BP-3 and HMS at 100 ℃ for 100 min. For SPE, the pH value of water sample was adjusted to 3-5. The Oasis HLB cartridges were employed and the solution of ethyl acetate and dichloromethane (1:1, v/v) was used as the eluting solvent, and good recoveries of the target compounds were obtained. The limits of detection (LODs) and the limits of quantification (LOQs) for the five target compounds in water samples were 0.5-1.2 ng/L and 1.4-4.0 ng/L, respectively. The recoveries of spiked water samples were 87.85%-102.34% with good repeatability and reproducibility (RSD<5%, n=3) for all the target compounds. Finally, the validated method was applied to analysis the representative UV filters in water samples collected from a wastewater treatment plant in Kunming city of Yunnan province.

Analysis of aldicarb and its metabolites in ginger using ultra performance liquid chromatography-tandem mass spectrometry coupled with multiplug filtration clean up with multiwalled carbon nanotubes

MA Lili, JIA Li, ZHOU Xinran, LIU Yan, FAN Xiaojing, PAN Canping

2014, 32 (6): 635-639. DOI: 10.3724/SP.J.1123.2014.02016

Abstract ( 746 ) [Full Text(HTML)] ()

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A simple and rapid pretreatment procedure was developed for the simultaneous determination of aldicarb and its metabolites, aldicarb sulfone and aldicarb sulfoxide, in ginger. The samples were extracted with acetonitrile, and then cleaned up with multiplug filtration using multiwalled carbon nanotubes (MWCNTS). The eluate was dried with nitrogen gas at room temperature, and redissolved in an acetonitrile-water (5:95, v/v) mixture, then quantified by ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) operated in positive multiple reaction monitoring (MRM) mode. A linear relationship was achieved in the range of 0.5-200 μg/L for the peak areas to the mass concentrations of the target compounds with the linear correlation coefficients (r²) higher than 0.99. The recoveries at three spiked levels of 2, 20 and 200 μg/kg were in the range from 71.4% to 89.8% with the relative standard deviations (RSDs, n=6) from 0.7% to 13.2% under the selected conditions. The limits of quantification (LOQ, S/N=10) of aldicarb, aldicarb sulfone, and aldicarb sulfoxide in ginger were 1.0, 2.0 and 1.0 μg/kg, respectively. The results demonstrate that the developed method is rapid, cost-effective, and can meet the requirements of the multiple pesticide residue analysis. The method is applicable to determine aldicarb and its metabolites in ginger.

Simultaneous determination of zeranols and chloramphenicol in foodstuffs of animal origin by combination immunoaffinity column clean-up and liquid chromatography-tandem mass spectrometry

WANG Qing, WANG Guomin, XI Cunxian, LI Xianliang, CHEN Dongdong, TANG Bobin, ZHANG Lei, ZHAO Hua

2014, 32 (6): 640-646. DOI: 10.3724/SP.J.1123.2014.01031

Abstract ( 834 ) [Full Text(HTML)] ()

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A combination immunoaffinity column (IAC-CZ) clean-up and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical method was successfully developed for the simultaneous determination of zeranols (ZER,α-zearalanol,β-zearalanol, zearalanone,α-zearalenol,β-zearalenol and zearalenone) and chloramphenicol (CAP) in foodstuffs of animal origin. The samples (fish, liver, milk and honey) were enzymatically digested by β-glucuronidase/sulfatase for about 16 h and then extracted with ether. The extracts were evaporated to dryness and then the residues were dissolved by 1.0 mL of 50% acetonitrile solution. After filtered and diluted with PBS buffer, the reconstituted solution were cleaned-up with a IAC-CZ and then analyzed by LC-MS/MS in multiple reaction monitoring (MRM) mode. The chromatographic separation was performed on a Shimadzu Shim-pack VP-ODS column with gradient elution by acetonitrile and 2 mmol/L ammonium acetate solution. The detection was carried out by electrospray negative ionization mass spectrometry in MRM mode. The proposed method was validated by the limit of detection (0.04-0.10 μg/kg), linearity (R²≥0.9990), average recoveries (70.9%-95.6%) and precisions (2.0%-11.8%). The developed method is reliable, sensitive and has good applicability. The combination immunoaffinity column was proved to be an effective pretreatment technique to decrease the matrix effect, and it met the requirements of residue analysis of co-occurring zeranols and chloramphenicol.

Determination of six progesterones in milk by on-line cleanup liquid chromatography-tandem mass spectrometry

DUAN Yongsheng, WANG Bingling, AI Lianfeng, GUO Chunhai, GE Shihui, ZHANG Jingwen, XU Niusheng

2014, 32 (6): 647-652. DOI: 10.3724/SP.J.1123.2014.01044

Abstract ( 719 ) [Full Text(HTML)] ()

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A new method using TurboFlow on-line cleanup liquid chromatography combined with tandem mass spectrometry (MS/MS) has been developed for simultaneous determination of six progesterones including 19-norethindrone, 17 α-hydroxyprogesterone, medroxyprogesterone, megestrol acetate, progesterone and melengestrol acetate in milk. Samples were extracted by acetonitrile. The analytes in extract were on-line purified directly on Cyclone-P purification column where the sample matrices were washed away. Subsequently, the analytes which were eluted from the extraction column onto Phenyl-Hexyl column were separated with a gradient elution, and detected with electrospray ionization mass spectrometry in the positive scan mode using multiple reaction monitoring (MRM). The isotope internal standards were employed for quantification. As a result, the linearities were satisfactory with the correlation coefficients of >0.999 at concentrations ranging from 0.1 μg/L to 50 μg/L. Based on the repeated analysis of a known blank sample, the limit of quantification (LOQ) is 0.5 μg/kg. Average recoveries of the analytes fortified at three levels (1, 5 and 25 μg/kg) ranged from 90.8% to 107.5%, and the relative standard deviations (RSDs) ranged from 6.3% to 11.8%. This proposed method is simple, rapid, sensitive and highly selective, and can be applied to simultaneous identification and quantification of the six progesterones in milk.

Simultaneous determination of 17 phthalate esters in Shengmaiyin by gas chromatography-triple quadrupole mass spectrometry

ZHANG Li, SHANG Chuxiang, SUN Cheng

2014, 32 (6): 653-657. DOI: 10.3724/SP.J.1123.2014.02015

Abstract ( 1037 ) [Full Text(HTML)] ()

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Phthalate esters (PAEs) are commonly used for plastic products as plasticizer. Once taken in by human, PAEs will cause diseases, such as endocrine disorders, cancer, etc. Shengmaiyin is a kind of Chinese medicine oral fluid whose packaging materials may include phthalate esters. If the phthalate esters migrated into the solution, it would lead to serious problem on the safety of drugs. In this study, a method of gas chromatography coupled to triple quadrupole mass spectrometry (GC-QQQ-MS) was developed for the simultaneous determination of 17 phthalate esters in Shengmaiyin samples. The samples were extracted with n-hexane by liquid-liquid extraction method before analysis. The separation was performed on an HP-5MS capillary column (30 m×0.25 mm×0.25 μm) with temperature programming. The MS/MS detection was performed under electron impact source (EI) in multi-reaction monitoring (MRM) mode. The good linear relationships were obtained in the range of 0.5-20 mg/L for all the target analytes. The average recoveries of the 15 PAEs were in the range of 91.8%-117.2%, except dimethyl phthalate and diethyl phthalate which were about 51.9% and 77.2%, respectively, and all the RSDs were in the range of 0.5%-5.4% (n=6). The limits of detection ranged from 0.04 to 16.76 μg/L. The developed GC-MS method is simple, accurate, sensitive, proprietary, and can be applied in the detection of the phthalate ester residues in Shengmaiyin.

Determination of urinary cotinine of children exposed to passive smoking by stable isotope dilution gas chromatography-triple quadrupole mass spectrometry

WANG Yun, HUANG Zhiqiang, YE Ying, ZHANG Ying, XIAO Shuiyuan

2014, 32 (6): 658-661. DOI: 10.3724/SP.J.1123.2014.01023

Abstract ( 841 ) [Full Text(HTML)] ()

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An analytical method for the determination of urinary cotinine of children exposed to passive smoking was established based on stable isotope dilution by gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The samples were extracted and purified with chloroform. The extracts were determined by GC-MS/MS in multiple reaction monitoring (MRM) mode. The cotinine-d₃ as an isotope internal standard was applied to quantify and confirm the urinary cotinine of children exposed to passive smoking. The method had a good linearity from 0.1 μg/L to 10 μg/L with the correlation coefficient (r)>0.998. The recoveries of the cotinine in blank urine were from 79.2% to 112.8% at spiked levels of 0.1, 1.0 and 10 μg/L, with relative standard deviations (RSDs) from 2.1% to 5.8%. The limit of quantification (LOQ) of the method was 0.1 μg/L. The developed method is accurate, sensitive, rapid and can be applied to detect urinary cotinine of children exposed to passive smoking at home.

Determination of three ester compounds in gasoline by two-dimensional gas chromatography

ZHAO Yan, XU Dongyu, LIN Haoxue, CHEN Xiaoyan, CHEN Zeyong

2014, 32 (6): 662-665. DOI: 10.3724/SP.J.1123.2014.01045

Abstract ( 677 ) [Full Text(HTML)] ()

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A simple and efficient method based on the technique of packed column switching-back flushing was established for the analysis of the ester compounds (including ethyl acetate, sec-butyl acetate, dimethyl carbonate) in gasoline. With the use of a non-polar pre-column, we successfully separated the components in gasoline by back flushing out components heavier than n-octane, while the lighter components and the ester compounds were flushed into a polar analytical column. In this method, external standard method was applied for quantification. As a result, good linear relationships existed among the three ester compounds in the range of 50 mg/L to 50000 mg/L. The linear correlation coefficients (r²) for ethyl acetate, sec-butyl acetate and dimethyl carbonate were 0.99999, 1.00000 and 0.99995, respectively. The relative standard deviations (RSDs) of standard samples in six continuous tests were within 1.0%. The recoveries were between 98.7% and 107.9%. The detection limit of the method (S/N=3) was 5 mg/L. No pretreatment was needed. This method is simple, accurate, quick as well as efficient, and can be used as an ideal method for the analysis of the ester compounds in gasoline.

Rapid determination of cyclamate in foods by capillary zone electrophoresis with indirect ultraviolet detection

CHEN Tong, DING Xiaojing, LI Yizheng, ZHAO Xudong, ZHAO Shan

2014, 32 (6): 666-671. DOI: 10.3724/SP.J.1123.2014.02011

Abstract ( 737 ) [Full Text(HTML)] ()

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A new method for the rapid determination of cyclamate in foods by capillary zone electrophoresis (CZE) with indirect ultraviolet detection was developed. The separation was carried out with an uncoated fused-silica capillary (75 μm i. d., total length 80 cm, effective length 70 cm). The separation buffer consisted of 2 mmol/L sodium benzoate, 10 mmol/L sodium carbonate and 0.5 mmol/L hexadecyl trimethyl ammonium bromide. The separation voltage was -30 kV and the detection wavelength was 200 nm. The liquid samples could be directly injected after dilution with ultrapure water. The solid samples were first grounded or cut into pieces, and then extracted with ultrapure water. Then, the mixed solution was centrifuged. The supernatant was directly injected or injected after dilution with ultrapure water. The analytes were determined by external calibration. The limits of detection (S/N=3) and the limits of quantification (S/N=9) were 8.9 mg/kg and 26.7 mg/kg, respectively. The linear range between the corrected peak area and the mass concentration was from 1.2 mg/L to 80 mg/L with the correlation coefficient of 0.9999. The average spiked recoveries of five replicates at three spiked levels (2.5, 10 and 20 mg/L) were 93.4%, 100.3% and 101.9% with the relative standard deviations of 6.7%, 2.0% and 2.2%, respectively. The intra-and inter-day precisions of the method were 2.6% and 4.5%, respectively. The method is simple and rapid with minimal sample pretreatment and reagent consumption. No solvent was needed throughout the whole process of analysis. The analysis could be completed within 11 min (6 min for rinsing and 5 min for separation). The newly established method was used for the determination of cyclamate in a proficiency test sample. The results were in good agreement with that of the National Standard method, which illustrated the accuracy of the present method. Then, seven food samples were analyzed using the current new method and satisfactory results were obtained.

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