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Chinese Journal of Chromatography
2014, Vol. 32, No. 3
Online: 08 March 2014

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Determination of kepone in water by liquid chromatography-tandem mass spectrometry ZHOU Li, DONG Liang, SHI Shuangxin, ZHANG Lifei, ZHANG Xiulan, YANG Wenlong, LI Lingling, HUANG Yeru 2014, 32 (3):  211-215.  DOI: 10.3724/SP.J.1123.2013.11053 Abstract ( 766 )   [Full Text(HTML)] () PDF (962KB) ( 221 )   An analytical procedure for the determination of kepone in water was described. Water samples were extracted by liquid-liquid extraction, and then cleaned-up. Chromatographic separation was performed on an Eclipse plus C18 column (100 mm×2.1 mm, 3.5 μm) with gradient elution using acetonitrile and water at a flow rate of 0.3 mL/min. The target compounds were determined in multiple reaction monitoring (MRM) mode via negative electrospray ionization (ESI-) and quantified by isotopic-dilution technique. Results showed that kepone existed as diol form and hemiacetal in acetone/acetonitrile and methanol respectively, the structures of which were confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Due to the polar nature of kepone, it was difficult to be eluted during clean-up procedure and it may be decomposed during sulfuric acid washing. Therefore, it could not be analyzed together with the other organochlorine pesticides. The calibration curve showed good linearity in the range of 5-100 μg/L with correlation coefficient (r2) of 0.999. The limit of detection was 0.70 ng/L and the limit of quantification was 2.8 ng/L in water. The average recoveries when spiked at 5, 40 and 100 ng/L in water were 95.1%-98.9%, and the relative standard deviations (RSDs) were 3.85%-4.72%. The method can be used to the determination of kepone in water due to its high sensitivity, good recovery and reproducibility.

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Simultaneous determination of ten constituents in the Chinese medicinal preparation Fufangxingxiangtu’erfeng capsules by ultra performance liquid chromatography with tandem mass spectrometry FAN Xiaosu, PANG Qian, XU Yuanjin 2014, 32 (3):  216-223.  DOI: 10.3724/SP.J.1123.2013.11008 Abstract ( 803 )   [Full Text(HTML)] () PDF (2786KB) ( 307 )   Using caffeic acid and icariin as internal standards, a method for the simultaneous determination of protocatechuic acid, protocatechuic aldehyde, chlorogenic acid, scutellarin, isochlorogenic acid C, baicalin, luteolin, apigenin, atractylenolide Ⅲ and atractylenolide I in Fufangxingxiangtu'erfeng capsules were established by ultra performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS). The separation was performed on a ZORBAX RRHD Eclipse Plus C18 column (50 mm×2.1 mm, 1.8 μm) by using water containing 0.3% formic acid and methanol as mobile phases with the gradient elution at a flow rate of 0.3 mL/min. The analytes were detected by a tandem mass spectrometer in the multiple reaction monitoring (MRM) mode via the switching of positive electrospray ionization (ESI+) and negative electrospray ionization (ESI-). Under optimum conditions, the calibration curves were linear in the range of 0.00300-24.0 mg/L for protocatechuic acid, 0.0170-2.00 mg/L for protocatechuic aldehyde, 0.0150-30.0 mg/L for chlorogenic acid, 0.00400-30.0 mg/L for scutellarin, 0.0105-24.0 mg/L for isochlorogenic acid C, 0.00300-30.0 mg/L for baicalin, 0.00300-5.0 mg/L for luteolin, 0.00600-1.50 mg/L for apigenin, 0.00150-4.00 mg/L for atractylenolide Ⅲ, and 0.000600-0.900 mg/L for atractylenolide I with the detection limits of 1.0, 11, 5.0, 1.5, 3.5, 1.0, 1.0, 2.0, 0.50, 0.20 μg/L, respectively. The average recoveries of the ten effective components were between 92.5% and 106% with all relative standard deviations not more than 3.2%. The developed method was rapid, simple, accurate, reproducible, and suitable for the quality control of the Fufangxingxiangtu'erfeng capsules.

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Simultaneous determination of four Sudan dyes in blood by solid-phase extraction combined with ultra-fast liquid chromatography-tandem mass spectrometry ZHU Hao, HUANG Kunyu, FU Jianfei, HU Yue, HUANG Xianni, CHEN Xiaohong, ZOU Baobo, JIN Micong 2014, 32 (3):  224-229.  DOI: 10.3724/SP.J.1123.2013.11005 Abstract ( 878 )   [Full Text(HTML)] () PDF (1266KB) ( 266 )   A method for the simultaneous determination of Sudan Ⅰ, Ⅱ, Ⅲ, and Ⅳ in blood samples by solid-phase extraction (SPE) combined with ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) has been established. The samples were extracted with acetonitrile by vortex and vibrate technique, and then the supernatant was diluted with equal volume of water and cleaned up by a C18 SPE column. The separation was performed on an Agilent Eclipse Plus C18 column (100 mm×2.1 mm, 1.8 μm) by gradient elution with acetonitrile containing 0.1% (v/v) formic acid and 0.1% (v/v) formic acid aqueous solution as the mobile phases. The electrospray ionization (ESI) source in the positive mode and multiple reaction monitoring (MRM) mode were used for the quantitative analysis. In addition, the phenomenon of E-Z optical isomer occurred by the azo group from Sudan Ⅲ and Ⅳ was found, and the influencing factors were discussed. The results showed that the calibration curves were in good linearity for the four Sudan dyes ranged from 0.1 to 20.0 μg/L with the correlation coefficients of more than 0.999. The average recoveries were from 93.0% to 108.2% with the relative standard deviations (RSDs) from 4.8% to 9.5%. The limits of detection (LODs) and the limits of quantification (LOQs) were 0.06 μg/L and 0.2 μg/L for the four analytes, respectively. The developed method is simple, rapid, and highly sensitive. It can be used for the determination of trace Sudan dyes in blood samples.

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Simultaneous determination of six aldehydes in water-based coatings by high performance liquid chromatography with pre-column derivatization CHEN Qian, ZHOU Yuyan, CHENG Yuxiao, LIN Miao 2014, 32 (3):  230-234.  DOI: 10.3724/SP.J.1123.2013.11028 Abstract ( 882 )   [Full Text(HTML)] () PDF (993KB) ( 271 )   A high performance liquid chromatography method with pre-column derivatization was developed for the simultaneous determination of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, n-valeraldehyde and p-tolualdehyde in water-based coatings. After ultrasonic extraction with water, the samples were derivatized with 2,4-dinitrophenylhydrazine (2,4-DNPH) in acetonitrile under acidic condition, then filtrated by 0.45 μm organic syringe filters for the determination. Systematic investigation was carried out on the dependence of the derivatization conditions such as the acidity regulator, pH value, reaction temperature, reaction time and other factors. The optimized conditions were as follows: the dilute hydrochloric acid solution as acidity regulator, the pH of the buffer solution of 3, the reaction temperature of 60 ℃, and the reaction time of 30 min. Under the conditions, a linear relation was achieved in the range of 0.08-2.0 mg/L for the peak area to concentration of the six aldehydes. The detection limits were 0.05-2.50 mg/kg. The recoveries of standard addition at the spiked levels of 2.0, 4.0, 6.0 mg/kg were 87.0%-112.8% with the relative standard deviations (RSDs, n=6) of 1.12%-9.54%. The results showed that this method has a wide linear range, good precision and accuracy, and it is suitable for the simultaneous determination of the six aldehydes in water-based coatings.

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Separation mechanism of oleanane and ursane pentacyclic triterpenoid isomers by coordination chromatography KAI Guiqing, LIU Liu, WANG Huanming 2014, 32 (3):  235-241.  DOI: 10.3724/SP.J.1123.2013.09015 Abstract ( 879 )   [Full Text(HTML)] () PDF (1285KB) ( 374 )   This paper focuses on the study of the separation mechanism of oleanane and ursane pentacyclic triterpenoid isomers by a coordination chromatographic method. Based on the calculation analysis,β-cyclodextrin (β-CD) and its derivatives were selected as the suitable agents. The experimental results showed that the resolution of madecassoside isomers with the addition of glucosyl-β-cyclodextrin (Glu-β-CD) to the mobile phase (11.95) was higher than that of the addition of β-CD (9.61) or dimethyl-β-cyclodextrin (DM-β-CD) (9.89). The formation of 1:1 inclusion complexes was assumed. The apparent formation constants (KF) of pentacyclic triterpenes with β-CD were determined by HPLC method. For asiaticoside-B, the KF value with the addition of Glu-β-CD (2534 L/mol) was larger than that with the addition of β-CD (1467 L/mol) or DM-β-CD (1373 L/mol). According to the infrared characteristic absorbing peaks and simulation, the methyl part of asiaticoside-B might enter into β-CD cavity while the carbonyl group of asiaticoside-B might not enter into the cavity of β-CD, and the large glycoside parts were kept outside, forming hydrogen-bond interaction with the exterior of β-CD cavity. The results of the separation of oleanane and ursane pentacyclic triterpenoid isomers by coordination chromatography indicated that, the separation mechanism might be attributed to the steric differences (the place of methyl group in E cyclic), which lead to different chromatographic behaviors.

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Topological models of retention index of thin-layer chromatogram for chiral organic acids LI Mingjian, WANG Yuxiao, FENG Hui, FENG Changjun 2014, 32 (3):  242-247.  DOI: 10.3724/SP.J.1123.2013.10018 Abstract ( 780 )   [Full Text(HTML)] () PDF (819KB) ( 145 )   On the basis of Kier's molecular connectivity indices and conjugated matrix, novel molecular connectivity indices (mGtv) were defined and calculated for 18 chiral hydroxyl acids and amino acids. The chiral connectivity indices (mCtv) were introduced by extending mGtv: mCtv=mGtv×wj, where wj is the chiral index. The quantitative structure-retention index relationship (QSRR) between the retention index (RM) of thin-layer chromatogram for the chiral organic acids and mCtv was studied by multivariate statistical regression. By leaps-and-bounds regression analysis, the best four-parameter QSRR model was set up, and the traditional correlation coefficient (R2) and the cross-validation correlation coefficient (Q2) of leave-one-out (LOO) were 0.973 and 0.950, respectively. The results demonstrated that the model was highly reliable and had good predictive ability from the point of view of statistics. From the four parameters (0Cpv, 2Cpv, Cchv, 5Cpv) of the model, it is known that the dominant influence factors of the retention index were the molecular structure characteristics of two-dimensional and the space factors: the chiral characteristics, the flexibility and the puckered degree of molecules for the chiral organic acids. The results showed that the new parameter mCtv had good rationality and efficiency for the retention indices of the chiral organic acids. Therefore, an effective method was provided to predict the retention indices of the chiral organic acids.

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Purification and characterization of the biosurfactant rhamnolipid LIU Yang, ZHONG Hua, LIU Zhifeng, JIANG Yongbing, TAN Fei, ZENG Guangming, LAI Mingyong, HE Yibin 2014, 32 (3):  248-255.  DOI: 10.3724/SP.J.1123.2013.10026 Abstract ( 1623 )   [Full Text(HTML)] () PDF (1435KB) ( 535 )   Biosurfactant rhamnolipid is a metabolic intermediate produced by microorganisms under a certain condition. There are the polar hydrophilic group and the non-polar hydrophobic group in rhamnolipid molecule which always exhibits high surface or interfacial activity. A reliable separation and purification method as well as component identification technique is essential for success of production process. The rhamnolipid was produced by aerobic fermentation using Pseudomonas aeruginosa CCTCC AB93066 in this study. It was separated from the culture by acid precipitation and purified by column chromatography until two groups of monorhamnolipid and dirhamnolipid were obtained. High performance liquid chromatography with mass spectrometry (HPLC-MS) examination showed that either the monorhamnolipid or the dirhamnolipid contained three major species. They were RhaC10C10, RhaC10C12-H2, RhaC10C12 for monorhamnolipid and Rha2C10C10, Rha2C10C12-H2, Rha2C10C12 for dirhamnolipid. The results of the study suggested that Pseudomonas aeruginosa CCTCC AB93066 is a good strain for rhamnolipid production. Acid precipitation-column chromatography technique is good for purification of rhamnolipid. Meanwhile, HPLC-MS is a reliable method for identifying components of rhamnolipid with high sensitivity and accuracy.

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Determination of three chlorophenols in red wine by sweeping-micellar electrokinetic chromatography coupled with dispersive liquid-liquid microextraction and reversed phase liquid-liquid microextraction SUN Jianzhi, HE Hui, LIU Shuhui 2014, 32 (3):  256-262.  DOI: 10.3724/SP.J.1123.2013.11004 Abstract ( 901 )   [Full Text(HTML)] () PDF (1106KB) ( 204 )   A method of dispersive liquid-liquid microextraction (DLLME) and reversed phase liquid-liquid microextraction (RP-LLME) procedures coupled with sweeping-micellar electrokinetic chromatography (sweeping-MEKC) was established to extract and determine the three chlorophenols (CPs) including pentachlorophenol (PCP), 2,4,6-trichlorophenol (TCP) and 2,4-dichlorophenol (DCP) in red wine. The influences of the parameters of two extraction steps and the electrophoresis conditions were investigated. The optimum extraction conditions were as follows: for DLLME, 3.5 mL red wine sample (pH 3.0, 120 g/L NaCl), 300 μL hexane (extraction solvent), extraction for 3 min, centrifugation for 3 min at 5000 r/min; for RP-LLME, 25 μL 0.16 mol/L NaOH solution, extraction for 2 min, centrifugation for 2 min at 5000 r/min. The optimum running buffer (pH 2.3) was an aqueous solution containing 25 mmol/L NaH2PO4, 100 mmol/L sodium dodecyl sulfate (SDS) and 30% (v/v) acetonitrile. The optimum on-line concentration conditions were as follows: sample matrix, 80 mmol/L NaH2PO4; hydrodynamic injection of 20 s at 20.67 kPa (3 psi). Under the optimum conditions, the excellent linearity was obtained over the range of 0.5-100 μg/L (r≥0.9910) for PCP and TCP, and 1.5-80 μg/L (r≥0.9851) for DCP. The limits of detection (S/N=3) were in the range of 0.035-0.114 μg/L. The average recoveries were in the range of 75.2%-104.7% with the relative standard deviations (RSDs) not more than 6.17%. The results indicated that the proposed method may find wide applications for the determination of trace CPs in various sample matrixes and other weak acidic organic contaminants.

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Simultaneous determination of nine pharmaceuticals and personal care products in waters by solid phase extraction-gas chromatography-mass spectrometry JIA Yanyan, TAN Jianhua, XU Chen, TANG Jiajun, WANG Yingli, XIE Qilai 2014, 32 (3):  263-267.  DOI: 10.3724/SP.J.1123.2013.11034 Abstract ( 894 )   [Full Text(HTML)] () PDF (1339KB) ( 307 )   An analytical method has been developed and validated for the simultaneous determination of nine pharmaceuticals and personal care products (PPCPs) in water samples, including salicylic acid, naproxen, ibuprofen, paracetamol, clofibric acid, triclosan, diclofenac, ketoprofen, bisphenol A. The qualification and quantification of the target compounds were performed by gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS-SIM). The water samples were concentrated and purified through Oasis HLB cartridges after the pH value of the water was adjusted to 3, then derivatized with trimethyl sulfonium hydroxide (TMSH) at room temperature, and determined by GC-MS-SIM using 2,4,5-fenoprop as internal standard. The conditions for sample pretreatment (e. g. solid phase extraction and derivatization) were studied. Under the optimized conditions, the recoveries were ranged from 50.7% to 115.4% with the relative standard deviations lower than 10%. The limits of detection were in the range of 0.03-0.30 μg/L and the limits of quantification were in the range of 0.15-1.50 μg/L. The method has been successfully applied to monitor the occurrence of the PPCPs residues in agricultural irrigation water in Dongguan, Guangdong Province. The four compounds were detected at maximum mass concentration range of 0.176-0.998 μg/L. It proved that this analytical method is sensitive, reliable and acceptable.

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Identification of pesticide residues in common fruits and vegetables by gas chromatography-quadrupole time-of-flight mass spectrometry LI Xiaoying, ZHANG Hongyi, CHANG Qiaoying, FAN Chunlin, PANG Guofang, CAO Zhe, WANG Wenwen 2014, 32 (3):  268-277.  DOI: 10.3724/SP.J.1123.2013.11046 Abstract ( 934 )   [Full Text(HTML)] () PDF (1393KB) ( 247 )   A new screening method was developed for the determination of 152 pesticide multi-residues in different chemical species with a Carbon NH2 column using solid-phase extraction (SPE) coupled with gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOF MS). In the first stage (MS1) accurate mass database, up to three-five ions of the pesticides were monitored. The presence of at least three ions and the accomplishment of the intensity ratio (Q/qi) within the established tolerances were used as the confirmation of intensity criteria. The pesticides which have less characteristic ions or the peaks of the characteristic ions detected were up the tolerance were determined in the second stage (MS2) and the spectral difference was evaluated using MS2 library for the identified. Cabbage, tomato, pear were selected as typical fruits and vegetables to spike and detected all the 152 pesticides at two concentration levels of 5.0 and 10.0 μg/kg. The recoveries in the range of 70%-120% at two concentration levels were 91.45% and 94.08% for cabbage, 88.20% and 88.80% for tomato, 86.84% and 92.10% for pear respectively. Using the established 152 pesticide MS2 library some suspected pesticides were identified, and at the same time the analysis scope was expanded.

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Mechanism research on the lupeol treatment on MCF-7 breast cancer cells based on cell metabonomics SHI Dongdong, KUANG Yuanyuan, WANG Guiming, PENG Zhangxiao, WANG Yan, YAN Chao 2014, 32 (3):  278-283.  DOI: 10.3724/SP.J.1123.2013.11010 Abstract ( 1177 )   [Full Text(HTML)] () PDF (1584KB) ( 368 )   The objective of this research is to investigate the suppressive effects of lupeol on MCF-7 breast cancer cells, and explore its mechanism on inhibiting the proliferation of MCF-7 cells based on cell metabonomics and cell cycle. Gas chromatography-mass spectrometry (GC-MS) was used in the cell metabonomics assay to identify metabolites of MCF-7 cells and MCF-7 cells treated with lupeol. Then, orthogonal partial least squares discriminant analysis (OPLS-DA) was used to process the metabolic data and model parameters of OPLS-DA were as follows: R2Ycum=0.988, Q2Ycum=0.964, which indicated that these two groups could be distinguished clearly. The metabolites (VIP (variable importance in the projection)>1) were analyzed by t-test, and finally, metabolites (t<0.05) were identified to be biomarkers. Eleven metabolites such as butanedioic acid, phosphoric acid, L-leucine and isoleucine which had a significant contribution to classification were selected and preliminarily identified due to the accurate mass. Cell cycle assay was analyzed by FACSCalibur. Since the cells in the phase of G1 were increased significantly after the treatment of lupeol, we speculated that lupeol has a blocking effect on the generation of succinyl-CoA and the reaction of substrate phosphorylation of tricarboxylic acid cycle of MCF-7 cells. This study provided a novel approach to the mechanism research on the lupeol treatment on MCF-7 breast cancer cells based on cell metabonomics.

Technical Notes

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Application of reversed-phase liquid chromatography-tandem mass spectrometry in the identification of protein and bioactivity peptides from rape bee pollen GUO Jing, YAN Jiaze, GUO Ming, JIN Yan 2014, 32 (3):  284-289.  DOI: 10.3724/SP.J.1123.2013.12032 Abstract ( 789 )   [Full Text(HTML)] () PDF (1084KB) ( 239 )   Based on the shotgun proteomic method, rape bee pollen protein was prepared with ultrasonic extraction and digested by trypsin, then separated and sequenced by reversed-phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS), followed by protein database searching. After the above analysis, 353 peptides were identified and the molecular biological functions of 239 proteins have been known. The identified molecular biological functions of these proteins mainly included binding activity, enzyme activity, transporter activity, inhibitor activity and so on. Five peptides were obtained after the screening and appropriate amino acid modification among the identified 353 peptides, according to the relationship between the sequence structure of the bioactivity peptide and angiotensin converting enzyme (ACE) inhibitor activity. The five peptides were speculated to have ACE inhibitor activity and synthesized to detect ACE inhibitor activity. The results showed that all of the five peptides had good ACE inhibitor activity. The peptides of AELDIVLALF and LAVNLIPFP among the five peptides displayed especially good ACE inhibition with half maximal inhibitory concentration (IC50) of (10.65±0.50) μmol/L and (23.66±1.08) μmol/L, respectively. This method is rapid, low-cost and achieves the goal of high-throughput screening of bioactivity peptides that greatly shorten the period of identification compared with traditional methods.

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Determination of morroniside concentration in beagle plasma and its pharmacokinetics by high performance liquid chromatography-tandem mass spectrometry XIONG Shan, LI Jinglai, ZHU Xiuqing, WANG Xiaoying, LÜ Guiyuan, ZHANG Zhenqing 2014, 32 (3):  290-293.  DOI: 10.3724/SP.J.1123.2013.11027 Abstract ( 790 )   [Full Text(HTML)] () PDF (907KB) ( 266 )   A sensitive, simple and specific high performance liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) method was developed for the determination of morroniside in the plasma of beagles administered via intragastric (ig) doses of morroniside. The method employed paeoniflorin as the internal standard and extracted by simple protein precipitation. The separation was achieved using an Inertsil ODS-SP column (50 mm×2.1 mm, 5 μm) with mobile phases of 1 mmol/L sodium formate aqueous solution and acetonitrile (gradient elution) at a flow rate of 0.4 mL/min. The detection was accomplished by a mass spectrometer using multiple reaction monitoring (MRM) in positive mode. Pharmacokinetic parameters were fitted by software DAS 2.0. The methodological study showed a good linear relationship of 2-5000 μg/L (r=0.9966) with a sensitivity of 2 μg/L as the limit of quantification. The precision, accuracy, mean recoveries and the matrix effects were satisfied with the requirements of biological sample measurement. The method described above was successfully applied to the pharmacokinetic study of morroniside in the beagle plasma samples. The area under the plasma concentration-time curves (AUC(0-∞)) of morroniside after single ig administration doses of 5, 15 and 45 mg/kg were (1631.20±238.50), (3984.05±750.38) and (10397.64±3156.34) μg/L·h. The relationship between dose and AUC showed a good linearity. The pharmacokinetic property of morroniside was proposed to be linear pharmacokinetics.

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Analysis of sulfonamide residues in pork and chicken by high performance liquid chromatography coupled with solid-phase extraction using multiwalled carbon nanotubes as adsorbent ZHAO Haixiang, LIU Haiping, YAN Zaoying 2014, 32 (3):  294-298.  DOI: 10.3724/SP.J.1123.2013.11041 Abstract ( 811 )   [Full Text(HTML)] () PDF (1473KB) ( 337 )   A multi-residue analytical method based on solid-phase extraction (SPE) with multi-walled carbon nanotubes (MWCNTs) as sorbent was developed. The determination of the sulfonamides (SAs) in pork and chicken was carried out by high performance liquid chromatography-ultraviolet detection (HPLC-UV). The clean-up conditions were optimized. The analytes were extracted by acetonitril and cleaned-up by MWCNTs SPE cartridge. The extract was re-dissolved with the Na2HPO4 buffer (pH 5.5-6.0) for loading, and was washed with acetone-hexane (5:95, v/v), then eluted with acetone-dichloromethane (1:1, v/v) from the column. The mobile phase used in the chromatographic separation consisted of a binary mixture of acetonitrile and 50 mmol/L NaH2PO4 with the volume ratio of 7:3. A wide linear range was 0.01-1.00 mg/L with the correlation coefficients above 0.998. The limits of detection (S/N=3) were 0.003 mg/L, and the limits of quantification (S/N=10) were 0.01 mg/L. The average recoveries were over 70% for the nine SAs in the spiked range of 0.02-0.2 mg/kg, with the relative standard deviations (RSDs) lower than 8%. This study indicated that the MWCNTs SPE cartridge is efficient for the clean-up of the SAs in animal tissues or products, and the method is simple, accurate and suitable for the quantification of the SAs residues.

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Simultaneous analysis of iodate, iodide, bromate and bromide by ion chromatography with ultraviolet detection LI Meng, YU Hong, ZHENG Xiurong 2014, 32 (3):  299-303.  DOI: 10.3724/SP.J.1123.2013.11002 Abstract ( 1263 )   [Full Text(HTML)] () PDF (851KB) ( 427 )   An analytical method of ion chromatography with ultraviolet detection has been developed and applied for the simultaneous determination of iodate, iodide, bromate and bromide. The separation was performed on a quaternary ammonium type anion exchange column with citric acid and acetonitrile as mobile phase. The effects of the detection wavelength, the kind and concentration of the mobile phase and other parameters on separation and detection of the four ions were investigated. The retention rules were studied and the chromatographic conditions were optimized. Under the conditions of 210 nm as detection wavelength, 0.9 mL/min as flow rate, 40 ℃ as column temperature, and 1.0 mmol/L citric acid-acetonitrile (85:15, v/v; pH 5.0) as mobile phase, the four ions were completely separated and the system peaks and other common anions didn't interfere with the determination. The detection limits of the four ions (S/N=3) were 0.07-0.16 mg/L. The relative standard deviations of the retention times and peak areas obtained by determining samples five times continuously were below 1%. The spiked recoveries of the four anions were from 98.0% to 102%. This method has been successfully used to determine ionic liquids synthesized by chemistry laboratory and underground water samples. The results were accurate and reliable.

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Determination of organic acids in rice wine by ion-exclusion chromatography LIN Xiaojie, WEI Wei, HE Zhigang, LIN Xiaozi 2014, 32 (3):  304-308.  DOI: 10.3724/SP.J.1123.2013.11023 Abstract ( 1179 )   [Full Text(HTML)] () PDF (838KB) ( 455 )   An ion-exclusion chromatographic method for the simultaneous determination of organic acids in rice wine was developed. An IC-Pak Ion Exclusion column (300 mm×7.8 mm, 7 μm) was used at 50 ℃. The mobile phases were H2SO4(phase A) and acetonitrile (phase B) (98:2, v/v) at a flow rate of 0.5 mL/min. The gradient elution program was as follows: 0-40 min, 0.01 mol/L H2SO4 to 0.02 mol/L H2SO4; 40-50 min, 0.01 mol/L H2SO4. The injection volume was 10 μL. The detection wavelength was set at 210 nm. The results showed that oxalic acid, maleic acid, citric acid, tartaric acid, malic acid, ascorbic acid, succinic acid, lactic, fumaric acid, acetic acid, propionic acid, isobutyric acid and butyric acid were completely separated and determined in 30 min. The linear correlation coefficients were above 0.9997 in the range of 0.001-1.000 g/L. Under the optimized conditions, the recoveries of organic acids in rice wine were in the range of 93.4%-103.8% with the relative standard deviations (RSDs, n=5) of 0.1%-1.5%. This method is feasible, convenient, fast, accurate and applicable for the quantitative analysis of the organic acids in rice wine.

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Determination of trace musk xylene and musk ketone in aquatic products by multiple adsorption synchronous purification-gas chromatography-mass spectrometry DING Liping, CAI Chunping, LIN Yonghui, WU Wenfan, FANG Xiang 2014, 32 (3):  309-313.  DOI: 10.3724/SP.J.1123.2013.11025 Abstract ( 813 )   [Full Text(HTML)] () PDF (834KB) ( 420 )   In order to investigate the residues of musk xylene and musk ketone in aquatic products, a method was established for the determination of the trace musk xylene and musk ketone in aquatic products by multiple adsorption synchronous purification (MASP)-gas chromatography-mass spectrometry (GC-MS). After extracted with acetonitrile, the samples were pretreated using MASP method including extraction, salting-out and purification processes, analyzed with GC-MS in the selected ion monitoring (SIM) mode, and then quantified by matrix-matched standard solution in external standard method. The analysis was carried out with a capillary column (DB-5 MS, 30 m×0.25 mm×0.25 μm) under electron ionization conditions. The quantification was performed using monitoring ions of m/z 282, 297, 265 for musk xylene and m/z 279, 294, 191 for musk ketone. The results showed good linearity in the range of 1-100 μg/kg for musk xylene and musk ketone with the correlation coefficients not less than 0.999, and the limits of detection (S/N=3) of 0.30 μg/kg. The average recoveries of musk xylene and musk ketone spiked in prawn, clam and sea eel blank samples at three spiked levels of 1.0, 2.0 and 10.0 μg/kg ranged from 79% to 104% and the RSDs were in the range of 1.6%-13.3%. The method is simple, rapid and accurate, and can be used for the routine analysis of musk xylene and musk ketone in aquatic products.

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Determination of trifluralin residue in aquatic products and edible oils by gas chromatography-negative chemical ionization mass spectrometry WANG Li, XIA Guanghui, SHEN Weijian, WU Bin, ZHANG Rui, LU Huiyuan, SHEN Chongyu, ZHAO Zengyun 2014, 32 (3):  314-317.  DOI: 10.3724/SP.J.1123.2013.12013 Abstract ( 1186 )   [Full Text(HTML)] () PDF (838KB) ( 336 )   A confirmatory method was established for the determination of trifluralin residue in aquatic products and edible oils with the technique of offline disperse solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry (DSPE-GC-MS/NCI). Trifluralin was extracted from aquatic products and edible oils with acetonitrile, and liquid-liquid partitioning formed by adding anhydrous magnesium sulfate followed by a simple cleanup step known as dispersive solid-phase extraction. The aliquot was analyzed by GC-MS/NCI using isotope internal standard method. The method was reliable and stable. The recoveries of trifluralin were in the range from 80% to 100% at three spiked levels of 1.0, 2.0, and 3.0 μg/kg, and the RSDs were not more than 10.3%. The linearity of method was good from 1 to 40 μg/L, and the LOD was 0.02 μg/kg. This method can be used as a conclusive evidence method for the determination of trifluralin residue in aquatic products and edible oils.