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Chinese Journal of Chromatography
2012, Vol. 30, No. 07
Online: 28 July 2012

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Determination of phthalic acid esters in imitation jewellery and investigation of their migration risk LAI Ying*, HUANG Zongping, GE Xiuxiu, LIN Rui, CHEN Hexiu 2012, 30 (07):  647-653.  DOI: 10.3724/SP.J.1123.2012.03013 Abstract ( 1967 )   [Full Text(HTML)] () PDF (243KB) ( 524 )   A reliable gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of 14 phthalic acid esters (PAEs) in imitation jewellery. The influences of sample pretreatment methods including microwave extraction, ultrasonic extraction, accelerated solvent extraction (ASE) and Soxhlet extraction on the determination of PAEs were investigated. The migration risk of dibutyl phthalate (DBP), bis(2-ethyl hexyl) phthalate (DEHP) and dioctyl phthalate (DOP) in plastic imitation jewellery was investigated under the simulated body temperature and sweat environment within 0 h to 168 h. The results showed that the target compounds can be effectively extracted with hexane-acetone (1:1, v/v) under microwave extraction for 35 min. The limit of quantification (LOQ) of the method was 5 mg/kg for 12 PAEs (25 mg/kg for diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP)). The calibration curves were linear within 0.1~50 mg/L (0.5~250 mg/L for DINP and DIDP) with the correlation coefficients above 0.99. The recoveries ranged from 90.95% to 98.67% at three spiked levels. The migration risk of DEHP was higher than DBP and DOP with 0.75% dissolved after soaking for 72 h under the simulated conditions. The sensitivity, recovery and selectivity of the method can meet the requirements of the practical work.

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Rapid determination of pesticide multiresidues in vegetables and fruits by accelerated solvent extraction coupled with online gel permeation chromatography-gas chromatography-mass spectrometry Yun-Fu OUYANG 2012, 30 (07):  654-659.  DOI: 10.3724/SP.J.1123.2012.03039 Abstract ( 1962 )   [Full Text(HTML)] () PDF (183KB) ( 397 )    A novel method was developed for the rapid determination of 22 representative pesticide residues in vegetables and fruits based on accelerated solvent extraction (ASE) coupled with online gel permeation chromatography-gas chromatography-mass spectrometry (GPC-GC-MS). The sample was extracted by accelerated solvent extraction with dichloromethane-acetone (1:1, v/v) and purified with a carbon/NH2 column, evaporated to dryness by nitrogen, then dissolved in cyclohexane-acetone (7:3, v/v), and finally identified and quantified by GPC-GC-MS system in selected ion monitoring (SIM) mode. The results showed that the linearities of the 22 pesticides were good in their linear ranges. The limits of detection (S/N=3) were 0.3~1.8 μg/kg. The limits of quantification (S/N=10) ranged from 1~6 μg/kg. The recoveries for all at three spiked levels in Chinese cabbages and apples ranged from 70.5% to 107.5% with the relative standard deviations (RSDs) of 2.1%~8.7%. The proposed method is accurate, sensitive and highly efficient in the extraction, and can be used for the quick determination of the pesticide multiresidues in vegetables and fruits.

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Determination of the residues of 3-methyl-quinoxaline-2-carboxylic acid and quinoxaline-2-carboxylic acid in animal origin foods by high performance liquid chromatography-tandem mass spectrometry ZHENG Ling, WU Yujie*, LI Yong, LI Lihua 2012, 30 (07):  660-664.  DOI: 10.3724/SP.J.1123.2012.02018 Abstract ( 2123 )   [Full Text(HTML)] () PDF (195KB) ( 448 )   A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous quantitative determination of 3-methyl-quinoxaline-2-carboxylic acid (MQCA) and quinoxaline-2-carboxylic acid (QCA) as the marker residues for carbadox (CBX) and olaquindox (OLA), respectively, in the muscles and livers of porcine and chicken and in the muscles of fish and shrimp. The MQCA and QCA were deproteinated with 5% metaphosphoric acid in 10% methanol followed by liquid-liquid extraction. Further clean-up was performed by solid phase extraction (SPE) through mixed mode anion-exchange columns (Oasis MAX SPE). The separation of the compounds was carried on a Waters Xterra MS C18 column (150 mm×2.1 mm, 5 μm) by a gradient elution using methanol and 0.2% formic acid as mobile phases. The analytes were detected by tandem mass spectrometry in multiple reaction monitoring (MRM) mode with positive electrospray ionization. The MQCA and QCA were quantified by internal standard method. The linear ranges were 1.0~20.0 μg/L and the correlation coefficients were not less than 0.9996. The average recoveries and relative standard deviations ranged from 62.4%~118% and 1.48%~28.1% respectively at the spiked levels of 0.1, 0.2 and 1.0 μg/kg for the both markers. The limit of quantitation (LOQ) was 0.1 μg/kg. The method is sensitive, accurate and suitable for the determination and confirmation of MQCA and QCA in animal origin foods.

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Analysis of six phenolic environmental estrogens in bullfrog blood by using dispersive solid-phase extraction and ultrafast liquid chromatography-tandem mass spectrometry ZHAO Yonggang, CHEN Xiaohong, YAO Shanshan, LI Xiaoping, JIN Micong 2012, 30 (07):  665-671.  DOI: 10.3724/SP.J.1123.2012.02028 Abstract ( 1955 )   [Full Text(HTML)] () PDF (360KB) ( 570 )   A rapid, sensitive and accurate method for the simultaneous determination of six phenolic environmental estrogens, i.e., bisphenol A (BPA), diethylstilbestrol (DES), dienestrol (DE), hexestrol (HEX), 4-(tert-octyl)-phenol (4-tOP) and 4-nonylphenol (4-NP) in bullfrog blood by dispersive solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry (dSPE-UFLC-MS/MS) was established. After protein precipitation, bullfrog blood samples were cleaned-up by dSPE method with ethylenediamine-functionalized Fe3O4 magnetic polymers (EDA-MPs) as adsorbent. The effects of precipitation solvents, adsorption time and the amount of EDA-MPs used on the recoveries of six phenolic environmental estrogens were investigated in detail. Chromatographic separation was performed on a Shim-pack XR-ODSIIanalytical column (100 mm×2.0 mm, 2.2 μm). The mass spectrometer was operated by using electrospray ion (ESI) source in the multiple reaction monitoring (MRM) mode. The results showed that the linearities were in the range of 0.5~100.0 μg/L with correlation coefficients (r2) not less than 0.9996 for all the six phenolic environmental estrogens. The limits of quantification (LOQs) (S/N＞10) in bullfrog blood samples were between 0.075 μg/L and 0.40 μg/L. The recoveries were between 95.0% and 110.0% at three spiked levels. The precision values expressed as relative standard deviations (RSDs) were in the range of 0.6%~6.3%. The developed method can be applied to the routine analysis of the six phenolic environmental estrogens in bullfrog blood samples.

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Determination of rhodamine B in spices by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry YIN Feng, DING Zhaowei, YANG Zhijian 2012, 30 (07):  672-676.  DOI: 10.3724/SP.J.1123.2012.02016 Abstract ( 2525 )   [Full Text(HTML)] () PDF (181KB) ( 535 )   Rhodamine B (RB), as an unlawful colour, is forbidden to add into foods by Chinese government. A solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) method for the determination of RB in spices has been developed. The sample was extracted by acetonitrile and then centrifugated, purified and enriched with a strong positive ion exchange SPE column (Bond Elut Plexa PCX SPE column) after adding 10 mL 1% trichloroacetic acid solution. The HPLC separation was performed on a Pursuit C18 column (100 mm×2.0 mm, 3 μm) by gradient elution with 0.1%(v/v) formic acid solution and methanol as the mobile phase. The analyte was detected by electrospray ionization in positive ion mode-MS/MS in multiple reaction monitoring (MRM) mode. The good linearity (R2＞0.99) was obtained over the range of 0.6~6 μg/L. The limit of quantification (LOQ) for RB was 1.2 μg/kg. The average recoveries were ranged from 80% to 121% at the spiked levels of 1.197, 2.992 and 5.985 μg/L, and the relative standard deviations (RSDs) were not more than 15%. The conditions of mobile phase elution gradients, extraction solvents, and SPE columns were optimized. This method is highly selective and has weak matrix effect for qualitative and quantitative analyses of RB in spices.

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Simultaneous determination of melamine and cyanuric acid in foodstuffs by solid phase extraction-hydrophilic interaction chromatography-tandem mass spectrometry ZHAO Shanzhen1*, DENG Xiaojun1, YI Xionghai1, HAN Li1, SHENG Yonggang1, ZHANG Xiaomei2, WU Qiaobin3 2012, 30 (07):  677-683.  DOI: 10.3724/SP.J.1123.2012.01021 Abstract ( 1811 )   [Full Text(HTML)] () PDF (287KB) ( 431 )   A method based on solid phase extraction-liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of melamine and cyanuric acid in foodstuffs is presented. The melamine and cyanuric acid residues were extracted by acetonitrile and water, degreased by hexane, and the extract was cleaned-up by a mixed-mode solid phase-extraction column (MCT) of hydrophilic functional silica gel sorbent and cation exchange resin. The LC separation was performed on a hydrophilic interaction chromatograph, the melamine and cyanuric acid were determined by MS/MS in positive-negative switched electrospray ionization mode, multiple reaction monitoring (MRM) mode, and quantified by isotope internal standard method. The melamine and cyanuric acid were linear in the range of 10~2500 μg/L with the correlation coefficients (r) higher than 0.99, and the limits of quantification were 25 μg/kg and 50 μg/kg, respectively. The recoveries of melamine and cyanuric acid spiked in animal-derived foods, plant-derived foods, milk and milk products were in the range of 70.0%~129.6% and 70.0%~128.6%, respectively, with the relative standard deviations (RSD) of 1.4%~23.3% and 2.8%~18.7%, respectively. The method can meet the requirement for the determination of melamine and cyanuric acid in foodstuffs simultaneously.

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Determination of antibiotics in oral hygiene products by high performance liquid chromatography-tandem mass spectrometry ZHOU Weijun1*, XIE Zhengfu1, SHAO Linzhi2 2012, 30 (07):  684-689.  DOI: 10.3724/SP.J.1123.2012.02039 Abstract ( 1792 )   [Full Text(HTML)] () PDF (295KB) ( 295 )   A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for simultaneous determination of 13 antibiotics in oral hygiene products, including five tetracyclines, three macrolides, two quinolones, one β-lactam and two lincosamides. The sample was extracted with 0.1% (volume percentage, same hereinafter) formic acid-acetonitrile (95:5, v/v), then centrifuged, filtered and diluted. The target compounds were separated on a C18 column (150 mm×2.1 mm, 5 μm) with a gradient elution of 0.1% formic acid and acetonitrile as the mobile phases, and detected by tandem mass spectrometry in positive electrospray ionization and multiple reaction monitoring (MRM) mode. The quantification of 13 antibiotics was performed by the external standard method. The calibration curves showed good linearity in the range of 5.0~50.0 μg/L with detection limits of 10.0 mg/kg. The recoveries of antibiotics in mouthwash and toothpaste samples at the three spiked levels of 10, 20 and 100 mg/kg were in the range of 80.1%~115% with the relative standard deviations in the range of 0.94%~8.69%. This method is accurate, reliable, simple, and suitable for the analysis of antibiotics in oral hygiene products.

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Preparation of flavonoid reference standards from Scutellariae Radix under the guidance of high performance liquid chromatography-mass spectrometry analysis GUO Henan1, YANG Xuedong1*, LIU Jun2, ZHENG Wenfeng1 2012, 30 (07):  690-695.  DOI: 10.3724/SP.J.1123.2012.02030 Abstract ( 2363 )   [Full Text(HTML)] () PDF (213KB) ( 434 )   Flavonoid reference standards were targeted-prepared from Scutellariae Radix under the guidance of high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis. With HPLC-MS analysis of Scutellariae Radix, 19 flavonoid components were identified by analyzing and comparing their retention times, ultraviolet spectra, and mass spectrometry data with literature. The separation and purification protocols of all targeted flavonoid reference standards were optimally designed according to the results of HPLC-MS analysis and related literature. The ethanol extract of Scutellariae Radix was suspended in water and extracted with petroleum ether, ethyl acetate, and n-butanol successively. The ethyl acetate extract and n-butanol extract were separately subjected to primary separation by low pressure reverse phase preparative chromatography. Then the fractions containing targeted compounds were further purified by low pressure reverse and normal phases preparative chromatography. Finally, baicalin and wogonoside reference standards were obtained from n-butanol extract; baicaelin, wogonin, and oroxylin A reference standards were obtained from ethyl acetate extract. The structures of the 5 reference standards were identified by mass spectrometry (MS) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. The HPLC analytical results showed that the purities of the 5 reference standards were all above 98%. It is demonstrated that the rapid targeted-preparation method under the guidance of the HPLC-MS analysis is applicable for the isolation and preparation of chemical components in traditional Chinese medicines.

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Analysis of amino acids in rat plasma by solid phase extraction-high performance liquid chromatography-electrospray tandem mass spectrometry and the application to radiation injury rat model TANG Xinxing, GU Yuan, CAI Shang, XU Meiling, WANG Chang* 2012, 30 (07):  696-704.  DOI: 10.3724/SP.J.1123.2012.01037 Abstract ( 2674 )   [Full Text(HTML)] () PDF (481KB) ( 612 )   A robust and sensitive high performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI MS/MS) method was developed with solid phase extraction (SPE) sample preparation. It was optimized for the analysis of various amino acids in rat plasma. Silica-based strong cationic exchange SPE cartridges were used to extract amino acids and minimize the ion-suppression effect. The SPE cleanup protocol was optimized and it was found that the sample loading pH was very critical for the recovery and reproducibility. When the plasma sample was mixed with 0.1 mol/L acetic acid (pH 2.8) and loaded on SPE cartridge, the recoveries and repeatability for most of the amino acids were satisfactory. The method was fully validated. The analytical characteristics such as total recoveries (33.6%~107.7%, except lysine and ornithine), linearities (r2＞0.99 except arginine), intra-day precisions (relative standard deviation (RSD)＜9.0%) and inter-day precisions (RSD＜19.1%) were satisfactory for most of the amino acids. Furthermore, the method was successfully applied to study the ionizing radiation exposure induced changes in amino acid concentration of plasma samples from rats. Experimental results showed that the ionization radiation could lead to metabolism disorder of plasma amino acids, and the degree of disorder was related with the degree of injury by the ionization radiation injury. Some of the amino acids may be potential biomarkers of ionization radiation injury. These results provide experimental basis for screening of new markers of the acute radiation damage.

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Determination of cefuroxime in liver-injured rat plasma by ultra fast liquid chromatography-tandem mass spectrometry via acidified protein precipitation ZHAO Longshan1, LI Qing1, YANG Wei2, HE Bosai1, WEI Binbin1, LIU Ran1, LIU Jingjing1, CHEN Xiaohui1, BI Kaishun1* 2012, 30 (07):  705-710.  DOI: 10.3724/SP.J.1123.2012.03001 Abstract ( 2045 )   [Full Text(HTML)] () PDF (229KB) ( 400 )   In order to investigate the pharmacokinetic profiles of cefuroxime lysine, a new second generation cephalosporins, in liver-injured rat model, an ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method for the determination of cefuroxime in liver-injured rat plasma was developed and validated. The plasma sample was pretreated by protein precipitation with acidified acetonitrile. The analytes were separated on a Shim-pack XR-ODS column (75 mm×3.0 mm, 2.2 μm) with acetonitrile-0.1% formic acid aqueous solution (40:60, v/v) as the mobile phase at a flow rate of 400 μL/min. The mass spectrometer was operated in multiple reaction monitoring (MRM) mode with a negative electrospray ionization (ESI) interface. The precursor to product ion transitions of m/z 423.2→206.8 and m/z 454.1→238.4 were selected to determine cefuroxime and cefotaxime (internal standard, IS), respectively. The linearities ranged from 0.01 to 1 mg/L and 1 to 400 mg/L (r＞0.99), and the limit of quantification of cefuroxime was 0.01 mg/L. The relative standard deviations (RSDs) of intra- and inter-day precisions were both less than 11.5%, and the accuracy (relative error) was between ~7.1% and 2.2%. The mean extraction recovery was more than 83.5%. The total run time was 3.0 min per sample. The method is simple and fast for the preliminary pharmacokinetic study of cefuroxime lysine in liver-injured rats.

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Fast determination of adenosine and cordycepin in Cordyceps and its deserted solid medium LI Chen1,2*, YAN Aiguo3, CAI Chunyan4, LIU Zhiping2 2012, 30 (07):  711-715.  DOI: 10.3724/SP.J.1123.2012.02037 Abstract ( 1506 )   [Full Text(HTML)] () PDF (209KB) ( 480 )   A fast analytical method for adenosine and cordycepin in Cordyceps and its deserted solid medium was developed by using a normal-phase cyan-group chromatographic column. The sample was extracted for 1.5 min using a microwave-assisted extraction system. The extraction was repeated twice. The analysis of adenosine and cordycepin was performed on an Eclipse XDB-CN column. The mobile phase was composed of methanol and water with a ratio of 7:93 (v/v) for isocratic elution. The detection wavelength was 260 nm. The composition and pH value of the mobile phase were investigated. The results showed that adenosine and cordycepin could be completely separated without matrix interference in 4.5 min. The linearity of the method was good with a linear correlation coefficient (r2) of 0.9998 for adenosine and 0.9995 for cordycepin. The limits of quantification (LOQs, S/N=10) of adenosine and cordycepin were 0.21 and 0.083 mg/L, respectively. The relative standard deviations (RSDs) of peak areas of six replicate injections were less than 2% both for intra-day and inter-day analysis. The average recoveries of adenosine and cordycepin ranged from 93.8% to 102.9% with the RSD not more than 3.62% (n=5). The developed method is simple, fast, accurate and low-cost, and it can be used in the fast detection of adenosine and cordycepin in Cordyceps, carpohole, the deserted solid medium and its praeparatum.

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Determination of melamine and ammeline in eggs and meat using hydrophilic interaction liquid chromatography LI Yanzhao1, HAO Weiqiang2*, WANG Yubo1, CHEN Qiang2, LI Jinchun1, SUN Xiaoli1 2012, 30 (07):  716-720.  DOI: 10.3724/SP.J.1123.2012.02011 Abstract ( 1631 )   [Full Text(HTML)] () PDF (167KB) ( 459 )   A hydrophilic interaction liquid chromatographic (HILIC) method for the determination of melamine and its degradation product ammeline in eggs and meat has been developed. The separation was carried out on a ZIC-HILIC column with 3 mmol/L NH4H2PO4 (pH 6.9)-acetonitrile (20:80, v/v) as mobile phase at the flow rate of 0.8 mL/min, and detected at 220 nm. Compared with the reversed-phase liquid chromatography, this method can avoid the use of ion pair reagents and thus simplify the composition of mobile phase. Under the above chromatographic conditions, melamine and ammeline had good peak shapes and moderate retention times. Good separation between these compounds and the substances that were naturally contained in the samples can be achieved. For the sample preparation, the analytes were first extracted with 0.1% phosphoric acid due to the basicity of melamine and ammeline. Then, metaphosphoric acid and acetonitrile were used to remove proteins and saccharides by precipitation. After the filtration and removal of acetonitrile by rotary evaporation under vacuum, the filtrate was cleaned-up by solid-phase extraction (SPE) technique in which a cation exchange column was used. The SPE column was activated by using methanol and 0.1% phosphoric acid. A solution of 5% ammonia methanol was chosen as eluent. The residues obtained from the eluant by evaporating the solvent were resolved in the mobile phase. It was found that there was a good linear relationship between concentration and detector response within the range of 0.4~40 mg/L. The limits of detection were 2 mg/kg for both melamine and ammeline. The average recoveries were between 80% and 105% in the spiked range of 2~10 mg/kg. The relative standard deviations were not more than 10%. The solutions of melamine and ammeline were stable in a month. The established method can be used in practice to determine melamine and ammeline simultaneously in egg and meat samples.

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Development of Water Quality Monitoring System for Sequential Determination of Ionic Nutrients by Ion-exclusion Chromatography with Spectrophotometric Detection on Cation- and Anion-exchange Resin Columns in Parallel Using Water Eluent Daisuke KOZAKI1*, Nobutake NAKATANI2, Masanobu MORI3,Nobukazu NAKAGOSHI1, Kazuhiko TANAKA1,4 2012, 30 (07):  721-727.  DOI: 10.3724/SP.J.1123.2012.02033 Abstract ( 1395 )   [Full Text(HTML)] () PDF (466KB) ( 353 )   A unified ion-exclusion chromatography (IEC) system for monitoring anionic and cationic nutrients like NH+4, NO-2, NO-3, phosphate ion, silicate ion and HCO-3was developed and applied to several environmental waters. The IEC system consisted of four IEC methodologies, including the IEC with ultraviolet (UV) detection at 210 nm for determining NH+4on anion-exchange separation column in OH- form connected with anion-exchange UV-conversion column in I- form in tandem, the IEC with UV-detection at 210 nm for determining simultaneously NO-2 and NO-3 on cation-exchange separation column in H+form, the IEC with UV-detection at 210 nm for determining HCO-3on cation-exchange separation column in H+form connected with anion-exchange UV-conversion column in I- form in tandem, and the IEC with visible-detection based on molybdenum-blue reaction for determining simultaneously silicate and phosphate ions on cation-exchange separation column in H+ form. These IEC systems were combined through three manually-driven 6-port column selection valves to select each separation column to determine selectively the ionic nutrients. Using this sequential water quality monitoring system, the analytical performances such as calibration linearity, reproducibility, detection limit and recovery were also tested under the optimized chromatographic conditions. This novel water quality monitoring system has been applied successfully for the determination of the ionic eutrophication components in sub-urban river waters.

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Analysis of piperidinium ionic liquid cations by ion chromatography with direct conductivity detection ZHANG Renqing, YU Hong*, LIU Yuzhen 2012, 30 (07):  728-732.  DOI: 10.3724/SP.J.1123.2012.02031 Abstract ( 1812 )   [Full Text(HTML)] () PDF (183KB) ( 379 )   A method of ion chromatography with direct conductivity detection was established to determine three piperidinium ionic liquid cations, i.e. N-methyl, ethyl piperidinium cation (［MEPi］+), N-methyl, propyl piperidinium cation (［MPPi］+) and N-methyl, butyl piperidinium cation (［MBPi］+). The effects of eluent types, eluent concentration and column temperature on the retention of the cations were investigated with sulfonic acid base cation exchange column using ethylenediamine-citric acid-acetonitrile as eluent. The results indicated that, with the increase of column temperature, the retention times of piperidinium cations were reduced, so the retention process of piperidinium cations was exothermic. The retentions of piperidinium cation homologue accorded with carbon number rule. The successful separation of the three piperidinium cations within 7 min was achieved using the optimized eluent of 0.2 mmol/L ethylenediamine-0.3 mmol/L citric acid-3% acetonitrile (pH 4.4) at a flow rate of 1.0 mL/min and the column temperature of 30 ℃. Under these conditions, the detection limits at a signal-to-noise ratio of 3 for ［MEPi］+, ［MPPi］+and ［MBPi］+were 0.14, 0.20 and 0.56 mg/L, respectively. The relative standard deviations (n=5) for peak areas were less than 1.2%. The method has been applied to the determination of piperidinium ionic liquids synthesized in chemical laboratory with the spiked recoveries of 97.6% to 105.1%. The method is accurate, reliable, rapid, and has better practicability.

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Determination of two mouldy compounds in cork by gas chromatography-mass spectrometry TANG Xi1, LIANG Ming1, LI Xiaojing1*, XIONG Wenming2, TANG Hong1, JIANG Xiaoli1, CHEN Jiamin1 2012, 30 (07):  733-737.  DOI: 10.3724/SP.J.1123.2012.03002 Abstract ( 1874 )   [Full Text(HTML)] () PDF (184KB) ( 385 )   A simple and fast method for the simultaneous determination of two mouldy compounds, 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA), in cork by gas chromatography-mass spectrometry (GC-MS) was established. The analytes were extracted by ultrasonic extraction with methanol, and purified then by solid phase extraction using primary secondary amine (PSA) as solid phase. After concentrating, the sample was analyzed by GC-MS and quantified by the external standard method. The linear ranges were from 10 μg/L to 10000 μg/L for TCA and TBA, the correlation coefficients (r2) of the calibration curves were above 0.99. The recoveries and the relative standard deviations (RSDs) of TCA and TBA in different kinds of corks were investigated. The recoveries ranged from 88.4% to 97.6% with the RSDs between 1.02% and 4.58% (n=6). The limits of detection (LODs) were 12 μg/L for TCA and 18 μg/L for TBA, and the limits of quantification (LOQs) were 40 μg/L for TCA and 50 μg/L for TBA. The method is suitable to the determination of TCA and TBA in corks.

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Determination of 14 heterocyclic aromatic amines in wine by liquid chromatography-ion trap-time of flight tandem mass spectrometry WANG Min1, GUO Dehua2, DING Zhuoping1*, YAO Jinting3, LI Fengge4, SU Min4 2012, 30 (07):  738-742.  DOI: 10.3724/SP.J.1123.2012.02041 Abstract ( 1811 )   [Full Text(HTML)] () PDF (187KB) ( 376 )   A rapid qualitative and quantitative analytical method was developed for the simultaneous determination of 14 heterocyclic aromatic amines (HAAs) in wine by liquid chromatography-ion trap-time of flight tandem mass spectrometry (LC-IT-TOF MS). HAAs were extracted from the samples by ethyl acetate under alkaline condition. The quantitation was carried out using internal standard method. The separation of HAAs was carried out based on Phenomenex Kinetex C18 100A column (100 mm×2.1 mm, 2.6 μm), with a gradient elution of acetonitrile and 30 mmol/L ammonium formate at a flow rate of 0.4 mL/min. The analytes were detected under positive-ion electrospray ionization mode. The results showed that the linear ranges of the 14 HAAs were 1~500 μg/L with limits of detection (signal/noise=3) of 0.33~1.77 μg/L. The average recoveries of all the compounds spiked in wine samples at three levels of 10, 50, 100 μg/L were in the ranges of 71.6%~96.4%, 72.9%~101.9%, 74.5%~103.3%, with the corresponding relative standard deviations (RSDs, n=6) of 2.9%~7.9%、1.7%~5.3%、1.8%~4.8%, respectively. The established method is simple, rapid, accurate, and has wide linear range and high sensitivity. It can be applied to the simultaneous analysis of the HAAs in wine.

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Determination of thiocyanate in dairy products by headspace gas chromatography SONG Jie, FU Yingwen, DU Lijun*, YAO Yating, MU Xiajie, KANG Lihua, ZHAO Youyou 2012, 30 (07):  743-746.  DOI: 10.3724/SP.J.1123.2012.02040 Abstract ( 1981 )   [Full Text(HTML)] () PDF (133KB) ( 393 )   A method for the determination of thiocyanate in dairy products by headspace gas chromatography was established. At first, the thiocyanate in dairy products was extracted by water. Then, the zinc acetate solution was added to the crude product for protein precipitation. The extract obtained above was centrifuged and the supernatant was added with chloramine T, which derivatized the thiocyanate ions to cyanogen chloride. The head-space vapor of the final extract was injected into a BP10 (14% cyanopropyl phenyl polysiloxane) gas chromatographic column, and detected by an electron capture detector (ECD). The target compound was quantified by external standard. The results showed that there was a good linearity between 0.005 mg/L and 0.1 mg/L with the correlation coefficient (r) of 0.997, and the limit of detection (signal-to-noise ratio(S/N) ≥10)was 0.1 mg/kg. The recoveries were 90.0%~110.0% with the relative standard deviations (RSDs) (n=10) of 4.98%~7.89% at the three spiked levels of 1.0, 2.0, 10.0 mg/kg. In conclusion, this method is simple, rapid and accurate. It can be applied in the determination of thiocyanate in dairy products, and meets the requirements of the daily testing. The method has been successfully used to test 18 kinds of commercially available dairy products and it was found that all the dairy products tested contained thiocyanate about 0.5~10 mg/kg.

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Determination of sixteen food additives in beverage by capillary zone electrophoresis LONG Weiran1,2, CEN Yihong2, WANG Xingyi2, BAI Yu1, LIU Huwei1* 2012, 30 (07):  747-751.  DOI: 10.3724/SP.J.1123.2012.03009 Abstract ( 2021 )   [Full Text(HTML)] () PDF (165KB) ( 402 )   A capillary zone electrophoretic (CZE) method for the separation of ten synthetic colorants such as acid red 92, patent blue V, uranine, acid red 1, indigo carmine, black BN, ponceau 6R, quinoline, amaranth, lemon yellow, and six preservatives including benzoic acid, sorbic acid, methyl paraben, ethyl paraben, propyl paraben, butyl paraben in beverages was developed. The effects of separation voltage, capillary temperature, pH and concentration of running buffer on the separation were investigated. A 46 cm×50 μm uncoated fused silica capillary was used with 70 mmol/L boric acid (pH 9.5) containing 4% (v/v) acetonitrile as background electrolyte solution. The detection wavelength was set at 220 nm, and the run voltage was 30 kV. The injection time was 5 s at 500 mPa and the temperature was 25 ℃. The linear relationship between the mass concentration and peak area for each of these analytes was obtained in the concentration range of 1~250 mg/L, with a correlation coefficient not less than 0.9938. The recoveries were between 95.8% and 108.7%. The method has been applied to the determination of food additives in real samples. The results showed that the method is simple, accurate, and suitable for the simultaneous determination of the sixteen food additives in beverage.