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Chinese Journal of Chromatography
2011, Vol. 29, No. 12
Online: 28 December 2011

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Progress of new mediums for sample preparation LI Gongke; HU Yuling 2011, 29 (12):  1145-1145.  DOI: 10.3724/SP.J.1123.2011.01145 Abstract ( 1047 )   [Full Text(HTML)] () PDF (88KB) ( 1194 )

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SSimultaneous determination of nine preservatives and sweeteners in yellow wine and wine by ultrafast liquid chromatography-tandem mass spectrometry CHEN Xiaohong, ZHAO Yonggang, YAO Shanshan, LI Xiaoping, JIN Micong* 2011, 29 (12):  1147-1154.  DOI: 10.3724/SP.J.1123.2011.01147 Abstract ( 2349 )   [Full Text(HTML)] () PDF (315KB) ( 1188 )   A sensitive and selective analytical method based on ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) was developed for the simultaneous determination of nine preservatives and sweeteners in yellow wine and wine. After the sample was diluted by pure water, the UFLC separation was performed on a Shim-pack XR-ODSII column (100 mm×2.0 mm, 2.2 μm) with a linear gradient elution program of acetonitrile-ammonium acetate(AmAc, 2.5 mmol/L)-trifluoroacetic acid (TFA, 0.01%, v/v) aqueous solution as the mobile phase. Electrospray ionization was applied and operated in the negative multiple reaction monitoring (MRM) mode. The results showed that the limits of detection (LODs, S/N>3) for the nine analytes were in the range of 0.03~15.0 μg/L, and the limits of quantitation (LOQs, S/N>10) were in the range of 0.1~50.0 μg/L. The calibration curves showed good linearity for the nine analytes in their detection ranges, and the correlation coefficients (r2) were larger than 0.998. The recoveries were between 96.2% and 100.5% with the relative standard deviations (RSDs) of 0.6%~5.4% for yellow wine, and between 96.0% and 104.0% with the RSDs of 0.7%~4.8% for wine. Additionally, the mass spectral characterizations of the nine food additives were studied and the fragmentation pathways were speculated. The method is sensitive, reproducible and adaptable to the simultaneous rapid determination of the nine food additives in different yellow wine and wine samples.

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Determination of aflatoxins in cashew by high performance liquid chromatography-tandem mass spectrometry BI Ruifeng1,2*, FAN Zhixian1, FU Meng2 2011, 29 (12):  1155-1159.  DOI: 10.3724/SP.J.1123.2011.01155 Abstract ( 2275 )   [Full Text(HTML)] () PDF (217KB) ( 937 )   A determination method of four aflatoxins in cashew was developed using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Sample was extracted with methanol-water (8:2, v/v) solution and a cleanup procedure with florisil column was adopted, after eluting with 5 mL acetone-water-formic acid (96:3.5:0.5, v/v/v) solution, the eluate was dried under N2 and the residue was redissolved with methanol. Four aflatoxins were separated in MG C18 column and detected by tandem mass spectrometry. The method was validated, the good correlation coefficients (r2>0. 997) of four aflatoxins were obtained within their respective linear ranges, the limits of quantification were less than 0. 2 μg/kg, mean recoveries were between 63. 0% and 78. 5%, relative standard deviations (RSDs) varied from 2. 8% to 9. 1%, meeting the requirements of trace assay. The sample preparation is simple, fast, and inexpensive, this method can be applied for the determination of aflatoxins in cashew.

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Determination of Alkylphenol and Alkylphenolpolyethoxylates in Brine by SPE and LC – MS WANG Jincheng1, XIONG Li2, ZHANG Haijun1, CHEN Jiping1* 2011, 29 (12):  1160-1164.  DOI: 10.3724/SP.J.1123.2011.01160 Abstract ( 2039 )   [Full Text(HTML)] () PDF (205KB) ( 979 )   A simple method based on solid phase extraction (SPE) coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS) was developed for the determination of octylphenol (OP), nonylphenol (NP), octylphenol ethoxylates (OPEOs) and nonylphenol ethoxylates (NPEOs) in brine. The extraction and cleanup of brine samples were performed on C18 solid-phase extraction cartridges. The complete separation among OP, NP, OPEOs and NPEOs was achieved on a Hypersil GOLD analytical column with methanol-water as the mobile phase. The determination was achieved using HPLC-MS with electrospray ionization (ESI) in selected ion monitoring mode. The results showed that the average recoveries of target compounds were 59.6%~104.4% and the corresponding relative standard deviations (RSDs, n=3) were 1.0%~13.5%. The instrumental limits of detection for the compounds were 0.08~3 μg/L. This method was applied to the analysis of the samples of seawater near Dalian coast. The results showed that both NP and NPEOs were detected in all samples and their concentrations in seaport and oil port were much higher than those in other sampling sites.

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Determination of three brominated flame retardants in human serum using solid-phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry XIAO Zhongxin1, FENG Jinfang2, SHI Zhixiong2*, LI Jingguang3, ZHAO Yunfeng3, WU Yongning2,3* 2011, 29 (12):  1165-1172.  DOI: 10.3724/SP.J.1123.2011.01165 Abstract ( 2409 )   [Full Text(HTML)] () PDF (271KB) ( 989 )   A solid-phase extraction (SPE) method for the simultaneous extraction of hexabromocyclododecanes (HBCDs)/tetrabromobisphenol A (TBBPA) and polybrominated diphenyl ethers (PBDEs) in human serum was developed. The extracts of HBCDs/TBBPA and PBDEs were determined using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-negative chemical ionization/mass spectrometry (GC-NCI/MS), respectively. The samples with the spiked internal standards, 13C12-HBCD, 13C12-TBBPA, 3,3′,4,4′-tetrabromodiphenyl ether (BDE-77) and 13C12-decabromodiphenyl ether (BDE-209), were extracted using the mixture of methyl tert-butyl ether (MTBE) and hexane (1:1, v/v). Then the co-extracted lipid was removed by sulfuric acid treatment. The newly obtained extract was purified using SPE with an LC-Si column and two fractions of HBCDs/TBBPA and PBDEs were finally got. The determination of HBCDs/TBBPA was performed on a 50 mm BEH C18 column in the multi-reaction monitoring (MRM) mode and the determination of PBDEs was on a 15 m capillary column in the selected ion-monitoring (SIM) mode. The limits of detection (LODs, S/N=3) ranged from 1.81 to 42.16 pg/g . The average recoveries were from 80.3% to 108.8% at two spiked levels of 0.5 and 5 ng/g for HBCDs, 0.05 and 0.5 ng/g for TBBPA and BDE-209 with the relative standard deviations between 1.02% and 11.42%(n=5). The developed method has been successfully applied to the determination of the 12 analytes in 42 pooled human serum samples. The levels of TBBPA in the samples ranged from ＜LOD to 6.58 ng/g, that of α-HBCD diastereoisomer ranged from ＜LOD to 7.22 ng/g, which was the most abundant isomer comparing with β- and γ-HBCD. The total PBDEs found ranged from 2.90 to 89.69 ng/g. This method was validated to be accurate and sensitive for the analysis of HBCDs, TBBPA and PBDEs in serum samples.

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Determination of polycyclic aromatic hydrocarbons in thermoplastic elastomer by gas chromatography-mass spectrometry ZHENG Lin1*, CHEN Haiting2, CHEN Jianguo1, FENG Zhen2, GAO Shufeng2, ZHOU Jie1 2011, 29 (12):  1173-1178.  DOI: 10.3724/SP.J.1123.2011.01173 Abstract ( 2111 )   [Full Text(HTML)] () PDF (331KB) ( 882 )   A simple and accurate method for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in thermoplastic elastomer by gas chromatography-mass spectrometry (GC-MS) has been developed. The effects of various operational parameters (e.g. sample pretreatment, extraction solvent, extraction method, extraction temperature, extraction time, etc) on the extraction efficiency were carefully investigated by analyzing different kinds of positive PAHs thermoplastic elastomer samples made by the manufacturer. The samples were extracted ultrasonically with toluene, concentrated to about 1 mL and then redissolved by cyclohexane. After being purified by dimethyl sulfoxide liquid-liquid extraction, 16 PAHs in the sample were analyzed by GC-MS and quantified by internal standard method. Different kinds of thermoplastic elastomer materials and products were analyzed by this method with the recoveries ranged from 70% to 117% and the relative standard derivations between 0.2% and 10.8%. The method is acceptable for the determination of PAHs in thermoplastic elastomer materials and products.

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Determination of residual acrylate monomers in adhesives by headspace gas chromatography-mass spectrometry LIU Dan1, CHEN Xiaoqing1*, WU Mingjian2, LI Shaoye2, DAI Yunhui2 2011, 29 (12):  1179-1182.  DOI: 10.3724/SP.J.1123.2011.01179 Abstract ( 2427 )   [Full Text(HTML)] () PDF (160KB) ( 1132 )   A method was developed for the determination of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate in adhesives by headspace gas chromatography-mass spectrometry (HS-GC-MS). The samples were treated at 100 ℃ for 30 min, then separated on a DB-WAX column (30 m×0.25 mm×0.25 μm) and determined by MS under selected ion monitoring mode and quantified by internal standard method. The established method showed good separation with the limits of detection (LODs, S/N=3) of 0.069~0.096 mg/kg and the limits of quantification (LOQs, S/N=10) of 0.23~0.32 mg/kg. The recoveries for acrylate monomers were in the range from 96.0% to 104.6% with the relative standard deviations less than 7.2%. The method is simple, accurate, rapid and highly sensitive. It can be applied to analyze the residual acrylates and methyl acrylates in adhesives.

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Analysis of aliphatic aldehydes and ketones in water-based adhesive by direct derivatization-ionic liquid gathering coupled with high performance liquid chromatography WAN Xiaohong1, WU Mingjian2, JIANG Xinyu1*, DAI Yunhui2, LI Shaoye2, GONG Shuguo2 2011, 29 (12):  1183-1187.  DOI: 10.3724/SP.J.1123.2011.01183 Abstract ( 2012 )   [Full Text(HTML)] () PDF (186KB) ( 894 )   A novel method was developed for trace analysis of aliphatic aldehydes and ketones in water-based adhesive based on 2,4-dinitrophenylhydrazine (DNPH) direct derivatization-1-butyl-3-methylimidazolium hexafluorophosphate (［BMIM］PF6) preconcentration coupled with high performance liquid chromatography (HPLC). The dispersive water-based adhesive emulsion directly reacted with 80 mg/L DNPH solution containing 0.44 mol/L phosphoric acid at 40 ℃ for 18 min. After centrifuging, 0.5 mL ［BMIM］PF6 was added to extract the derivatives at 30 ℃. The ionic liquid (IL) phase was filtered and then analyzed by HPLC. The separation was achieved by using a Dionex Acclaim Explosive E2 column (250 mm×4.6 mm, 5 μm) under the gradient elution with acetonitrile and water as mobile phases at the flow rate of 1.2 mL/min. The column temperature was 35 ℃, and the detection wavelength was 365 nm. The results showed that the limits of detection (LODs) were 0.022~0.221 mg/kg, and the limits of quantification (LOQs) were 0.073~0.738 mg/kg. The relative standard deviations (RSDs) were in the range of 3.5%~7.3%, and the recoveries were 84.0%~102.5% for 8 aliphatic aldehydes and ketones. Compared with solvent extraction, the established method has the advantages of lower LOD and LOQ, and is more stable and precise. This method is practical for the determination of aliphatic aldehydes and ketones in water-based adhesives.

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Effects of trace water in mobile phase on enantioseparation of α-propionate derivatives in normal phase chromatography XIA Tingting, ZHANG Xiaoxiang, GU Fang, CHEN Jingwen, CAI Xiyun* 2011, 29 (12):  1188-1193.  DOI: 10.3724/SP.J.1123.2011.01188 Abstract ( 1711 )   [Full Text(HTML)] () PDF (293KB) ( 796 )   Trace water was added as a modifier of the mobile phase to achieve enantioseparation of α-propionate pollutants and their degradation products in normal phase high performance liquid chromatography (HPLC). A Chiralcel OJ-H column (25 cm×4.6 mm, 5 μm) was used with hexane-isopropanol-acetic acid as the mobile phase. The flow rate of the mobile phase was 0.8 mL/min. The results indicated that the addition of trace water differentially improved enantiomeric resolution of chiral α-propionate compounds, depending on the amount of water added and chemical structure of the analytes. It is primarily ascribed to the fact that trace water bound to chiral stationary phase and competed with the analytes. Moreover, trace water affected pH values of the mobile phase and the dissociation of free acids, thereby induced the variation in resolution efficiency. Additionally, the free acids were more sensitive to trace water than their neutral analogues (i.e., amides and carboxylic esters), in terms of the different roles of enthalpy and entropy terms.

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A method for the analysis of overlapped peaks in the high performance liquid chromatogram based on spectrum analysis LIU Bao1,2,3*, FAN Xiaoming1, HUO Shengnan1, ZHOU Lili1, WANG Jun1, ZHANG Hui1, HU Mei1, ZHU Jianhua1 2011, 29 (12):  1194-1198.  DOI: 10.3724/SP.J.1123.2011.01194 Abstract ( 1684 )   [Full Text(HTML)] () PDF (354KB) ( 788 )   A method was established to analyse the overlapped chromatographic peaks based on the chromatographic-spectra data detected by the diode-array ultraviolet detector. In the method, the three-dimensional data were de-noised and normalized firstly; secondly the differences and clustering analysis of the spectra at different time points were calculated; then the purity of the whole chromatographic peak were analysed and the region were sought out in which the spectra of different time points were stable. The feature spectra were extracted from the spectrum-stable region as the basic foundation. The nonnegative least-square method was chosen to separate the overlapped peaks and get the flow curve which was based on the feature spectrum. The three-dimensional divided chromatographic-spectrum peak could be gained by the matrix operations of the feature spectra with the flow curve. The results displayed that this method could separate the overlapped peaks.

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Determination of seven phenoxyacid herbicides in environmental water by high performance liquid chromatography coupled with three phase hollow fiber liquid phase microextraction PENG Xiaojun*, PANG Jinshan, DENG Aihua 2011, 29 (12):  1199-1204.  DOI: 10.3724/SP.J.1123.2011.01199 Abstract ( 1813 )   [Full Text(HTML)] () PDF (241KB) ( 947 )   A novel method for the simultaneous determination of seven phenoxyacid herbicides such as dicamba, fluroxypyr, 4-chlorophenoxyacetic acid (4-CPA), 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4-dichlorophenoxybutyric acid (2,4-DB) and 4-(2-methyl-4-chlorophenoxy)butyric acid （MCPB） in environmental water by three phase hollow fiber liquid phase microextraction (HF-LPME) coupled with high performance liquid chromatography (HPLC) was developed. In order to optimize the experimental conditions, the orthogonal test has been used. The effects of extraction solvent, pH of the donor phase and acceptor phase, extraction time, stirring speed and salt concentration on the detection were investigated. The optimal experimental conditions were as follows: octanol as organic solvent, pH 3 of donor phase, pH 12 of acceptor phase, extraction time of 30 min, stirring speed of 400 r/min. The results showed that the proposed method provided a wide linear range for 7 phenoxyacid herbicides with correlation coefficients of 0.9953~0.9988. The detection limits ranged from 0.2 to 1.0 μg/L. The enrichment factors were in the range of 76.7~121. The recoveries were in the range of 68%~104% and the relative standard deviations (RSDs) were less than 8.1% for the environmental water samples. The method has the advantages of sensitivity, simplicity, fastness and the use of very small amounts of organic solvent. The method can meet the requirements of the determination of trace phenoxyacid herbicides in the environmental water samples, and the study provided a useful method for the analysis of trace substances in water samples.

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Rapid determination of propranolol enantiomers in rat plasma by column-switching-high performance liquid chromatography WU Xiaoyu1, WANG Rong1,2*, XIE Hua1, WANG Jianfeng1, JIA Zhengping1,2*, ZHANG Qiang1, WANG Xianhua1 2011, 29 (12):  1205-1209.  DOI: 10.3724/SP.J.1123.2011.01205 Abstract ( 1963 )   [Full Text(HTML)] () PDF (218KB) ( 837 )   A high performance liquid chromatographic (HPLC) method with column-switching was developed and validated for rapid determination of two propranolol enantiomers in rat plasma. The column of restricted-access media was used as a pre-treatment column and a Chiralcel OD-RH was used as analytical column. The plasma samples were injected directly into the pre-treatment column to remove plasma protein and endogenous constituents as well as to retent the propranolol enantiomers in the column using the mobile phase of borate buffer (pH 8.5)-methanol (95:5, v/v) at the flow rate of 1.0 mL/min. Then the propranolol enantiomers were transferred to the Chiralcel OD-RH column using the mobile phase of isopropanol-ethanol-0.2 mmol/L borate buffer (pH 8.5) (30:30:40, v/v/v) at a flow rate of 0.8 mL/min by column-switching technology. The column-switching time was 3.0 min, the used wavelength was 293 nm and the column temperature was set at 25 ℃. The calibration curve showed excellent linear relationship (r=0.9995) in the concentration range from 25 mg/L to 500 mg/L for propranolol enantiomers in plasma. The intra-day and inter-day assay precisions and accuracies were well and the relative standard deviations (RSDs) were less than 5%. The average recoveries (n=6) of the two enantiomers at 3 spiked levels were from 97.89% to 101.56%. All the values of the method validation were within the generally accepted criteria for biological sample analysis. The results show that the method is convenient, quick, sensitive and accurate. The method was successfully applied in the determination of propranolol enantiomers in rat blood pharmacokinetics study.

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Stability evaluation of chemical compositions of Rhizoma gastrodiae with 60Co-γ irradiation by high performance liquid chromatography YANG Xiaorong1*, HUANG Min2, LIU Sujun1, SONG Jiuhua1 2011, 29 (12):  1210-1215.  DOI: 10.3724/SP.J.1123.2011.01210 Abstract ( 1476 )   [Full Text(HTML)] () PDF (194KB) ( 818 )   The main chromatographic fingerprint peaks of Rhizoma gastrodiae were established for evaluating the stability of chemical compositions of Rhizoma gastrodiae with 60Co-γ irradiation to control the dosage of 60Co-γ irradiation sterilization by high performance liquid chromatography (HPLC). Eight Rhizoma gastrodiae samples were analyzed. The chromatographic fingerprints of Rhizoma gastrodiae were constructed with 14 common fingerprint peaks, and its 10 main peaks were identified using the similarity evaluation system of chromatographic fingerprints of traditional Chinese medicine (version 2004 A) recommended by State Food and Drug Administration of China. The relative standard deviations of the peak areas of the 10 main peaks were used to evaluate the stability of corresponding chemical compositions of Rhizoma gastrodiae with 60Co-γ irradiation. The results showed that the compositions of 3 of the 10 main peaks were influenced and a good relationship was obtained between the influence and 60Co-γ irradiation doses for the eight Rhizoma gastrodiae samples. Some chemical components of Rhizoma gastrodiae weren’t steady after 60Co-γ irradiation, so a low dosage should be selected for 60Co-γ irradiation sterilization.

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An embedded peak recognition algorithm design for chromatography data in portable gas chromatographic instrument LUO Weidong*, TANG Luxi, ZHANG Yun, ZHOU Haolin 2011, 29 (12):  1216-1221.  DOI: 10.3724/SP.J.1123.2011.01216 Abstract ( 2003 )   [Full Text(HTML)] () PDF (337KB) ( 900 )   The evaluation and validation of an embedded peak recognition algorithm design for chromatography data analysis are presented. This portable gas chromatographic (GC) system can easily generate the measurement results directly without computer (PC) connecting in the field. In this research project, we demonstrated the sequential mapping as the peak recognition method to distinguish each part of the chromatographic peak. The new recognition algorithm not only reduces the dependence on the slope threshold, but also improves the relativity and accuracy of the data analysis process. The practice showed that the embedded analysis system can detect all the components even in the complex cases. Its output result was proven to be comparable to the Chemstation software data processing result. This portable GC design meets the analysis demand in the field and improves the convenience for its quick time response.

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Preparation of chiral monolithic column with covalently bonded cellulose and their application to rapid enantioseparation WANG Jiabin1, WANG Xiao2, LI Jianhua1, L Haixia3, LIN Xucong2, XIE Zenghong2, ZHANG Qiqing1* 2011, 29 (12):  1222-1229.  DOI: 10.3724/SP.J.1123.2011.01222 Abstract ( 2095 )   [Full Text(HTML)] () PDF (392KB) ( 892 )   A chiral monolithic capillary column for rapid enantioseparation was prepared by covalently bonding of cellulose tris(4-methylbenzoate) (CTMB) on N-acryloxysuccinimide-based monolith. The preparation and derivatization conditions of the monolithic column were optimized. The successful grafting of CTMB was confirmed on the characterizations of the infrared spectrum and the cathodic electroosmotic flow (EOF). The effects of acetic acid concentration and methanol content on the enantioseparation were studied. The solvent resistance, reproducibility and stability of the monolithic column have also been investigated. The rapid enantioseparation of the five solutes (phenylalanine, tyrosine, tryptophan, propranolol and phenylethanol) with resolution (Rs) values up to 1.31 was achieved within 1.2 min on the prepared chiral capillary monolithic column by capillary electrochromatography.

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Determination of baclofen using micellar electrokinetic chromatography with laser induced fluorescence detection WANG Yufei, YANG Jiajia, CAI Yuanli, LIN Xia, LI Hui* 2011, 29 (12):  1230-1235.  DOI: 10.3724/SP.J.1123.2011.01230 Abstract ( 2046 )   [Full Text(HTML)] () PDF (249KB) ( 804 )   A novel micellar electrokinetic chromatographic method with laser induced fluorescence detection after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole(NBD-Cl) was developed for the determination of muscle relaxant drug baclofen (BAL). After optimization, baseline separation of the derivatives of BAL and gabapentin (internal standard) was obtained within 7 min in a running buffer (pH 9.75) composed of 15 mmol/L sodium borate, 20 mmol/L sodium dodecyl sulfate and 10% (v/v) acetonitrile. The separation voltage was 17.5 kV. The column temperature was 25 ℃. The samples were injected by a pressure of 3.45 kPa(0.5 psi) for 3 s. The method has a linear range of 0.025~25 mg/L for BAL with the correlation coefficient of 0.9999. The limit of detection (LOD, S/N=3) and the limit of quantification (LOQ, S/N=10) were 0.90 μg/L and 6.25 μg/L, respectively. The developed method was used for the analysis of BAL pharmaceutical preparation and urine samples spiked with BAL standard. The ranges of recovery were 101.6%~107.9% for BAL preparation and 107.0%~109.6% for urine samples. This method can be applied to the quality assessment of baclofen drug products, and provide supplementary means for the drug metabolism research of baclofen.

Technical Notes

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Determination of phthalate plasticizers in foods by high performance liquid chromatography with gel permeation chromatographic clean-up ZHANG Chunyu1, WANG Hui2, ZHANG Xiaohui1, MA Zhongqiang1, DENG Wanmei1, HU Ke1, DING Mingyu2* 2011, 29 (12):  1236-1239.  DOI: 10.3724/SP.J.1123.2011.01236 Abstract ( 2276 )   [Full Text(HTML)] () PDF (135KB) ( 983 )   A method of gel permeation chromatography-high performance liquid chromatography (GPC-HPLC) was established for the simultaneous determination of 5 main phthalate plasticizers in foods (edible oil, instant noodles, fried pastries, Saqima, etc.). The samples were extracted with petroleum ether in an ultrasonator, purified by a GPC column, and analyzed by HPLC. The chromatographic separation was achieved on a Labtech-C18 column (250 mm×4.6 mm, 5 μm) using acetonitrile and water mixture as the mobile phases in a gradient elution mode. The developed method exhibited a linear correlation coefficient of more than 0.997 and the detection limits of 3.25~13.4 μg/L. The spike recoveries were between 70.4% and 113.6% with the relative standard deviations (RSDs, n=3) of 0.3%~5.8% at the spiked level of 50 mg/L. This method is simple, rapid and practical, and can be used for the simultaneous determination of PAEs in grease food samples.

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Determination of chlorfluazuron residue in foods by high performance liquid chromatography DU Lijun*, SONG Jie, ZHANG Lina, LIU Hongyan 2011, 29 (12):  1240-1243.  DOI: 10.3724/SP.J.1123.2011.01240 Abstract ( 1926 )   [Full Text(HTML)] () PDF (135KB) ( 858 )   A method for the determination of chlorfluazuron residue in foods by high performance liquid chromatography (HPLC) was developed. The samples were extracted with hexane or acetonitrile. After cleaned up with Florisil-solid phase extraction (SPE), the samples were analyzed by the separation on a C18 chromatographic column with an acetonitrile and water (85:15, v/v) mixed solution as the mobile phase and the determination with an ultraviolet detector at 260 nm. The linear range was 0.05~2.0 mg/L, the correlation coefficient was 0.9998 and the limit of quantification (S/N=10) was 0.05 mg/kg. The recoveries were 82.1%~102.5% with the relative standard deviations (n=10) of 3.00%~6.25% at the three different spiked levels of 0.05, 0.1 and 1 mg/kg. The method is easy, fast, accurate and consuming less sample and organic solvents. It can be applied in the determination of chlorfluazuron in foods.

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Separation and purification of flavones from Nelumbo nucifera Gaertn. by silica gel chromatography and high-speed counter-current chromatography XU Shuangshuang1, SUN Yu2, JING Feng1, DUAN Wenjuan3, DU Jinhua1, WANG Xiao3* 2011, 29 (12):  1244-1248.  DOI: 10.3724/SP.J.1123.2011.01244 Abstract ( 2088 )   [Full Text(HTML)] () PDF (230KB) ( 1090 )   Three flavones were isolated and purified from Nelumbo nucifera Gaertn. by the combination of silica gel chromatography and high-speed counter-current chromatography (HSCCC). The crude extract of N. nucifera was separated by silica gel chromatography and the fraction containing flavones was obtained. Then, the fraction was separated by HSCCC with two phase solvent systems composed of ethyl acetate-ethanol-water-acetic acid (4:1:5:0.025, v/v/v/v). The upper phase was as the stationary phase and the lower phase as the mobile phase. Under the conditions of a flow rate of 2.0 mL/min, while the apparatus rotated at 800 r/min and the detection wavelength was at 254 nm, 6.1 mg of quercetin-3-O-β-D-glucuronide, 14.8 mg of myricetin-3-O-β-D-glucopyranoside and 20.2 mg of astragalin were obtained from 150 mg of the crude sample in one step. The purities determined by high performance liquid chromatography (HPLC) were 97.0%, 95.4% and 96.3%, respectively. The structures of the target compounds were identified by electrospray ionisation mass spectrometry (ESI-MS),1H-nuclear magnetic resonance(1H-NMR) and 13C-nuclear magnetic resonance(13C-NMR). This method that has practical value not only saves solvent but also is convenient. It is effective in the separation of flavones from N. nucifera, and provides theoretical foundation for the further development and use of N. nucifera resources.