最新刊期
卷 31 ， 期 7 ， 2012
- 摘要：An apposing liquid microjunction surface sampling probe（LMJ-SSP) system combined with air flow-assisted ionization（AFAI) was developed for the biopharmaceutical analysis.At the same time，the stability of the LMJ-SSP-AFAI-MS method was validated by the analysis of the added 10-hydroxy camptothecin in tissue section.And then the LMJ-SSP-AFAI system was applied in the distribution analysis of S-(+)-deoxytylophorinidine（CAT)，a potential anticancer agent，in the main organs of a whole-body rat tissue section.The key parameters of the LMJ-SSP-AFAI-MS method were optimized to enable stable sampling status and sensitive analysis，including length of imbibing capillary（24 cm)，composition of extraction solvent（ACN∶H2O,70∶30，containing 0.1% FA)，flow rate of extraction solvent（7.5 μL/min) and gap between probe tip and sample surface（20 μm).The distribution information of CAT obtained with the LMJ-SSP-AFAI-MS system can provide possible indication for its drug efficacy as well as side effect and toxicity.In addition，the LMJ-SSP-AFAI-MS method was demonstrated to be a sensitive tool for direct surface analysis of analytes in complex matrix of large objects remotely under ambient environment without intensive sample preparations,which can be used for preliminary experiment prior to IMS research.By providing the information about the organs which should be paid more attention，the varied distributions information of drugs in different organs will guide the preparations of the whole body section with all the targeted organs in one section and the optimization of whole body IMS experimental parameters.What is more，the LMJ-SSP-AFAI-MS method can provide an alternative way for the distribution analysis of drug candidates during drug discovery.关键词：surface sampling probe;air flow assisted ionization;mass spectrometry;whole body section;drug distribution
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发布时间： - 摘要：A procedure for the fast trace analysis of nitroimidazoles(including metronidazole，ronidazole，dimetridazole and ipronidazole) and their hydroxyl-metabolites(2-hydroxymethyl-1-methyl-5-nitroimidazole，hydroxymetronidazole，hydroxyipronidazole) was developed by liquid chromatography coupled with quadrupole/linear ion trap mass spectrometry.Honey samples were extracted with phosphate buffer(0.5 mol/L，pH 8.8)followed by liquid-liquid partition with ethyl acetate，and cleaned up by high speed freezing centrifugation.The separation of analytes was made on a C18 column using a mobile phase of 0.1% formic acid-methanol by gradient elution.A scheduled multiple reaction monitoring(sMRM) in positive mode as survey scan and an enhanced product ion(EPI) scan as dependent scan in an information-dependent acquisition(IDA) experiment was employed in mass spectrometry acquisition.Stable isotope-labeled analogues were used as the internal standards for quantitation.Confirmative analysis was performed through EPI spectra matching based on on-line lab-built library. Seven analytes showed good linearities in the range of 0.125-50.0 μg/L，with lower limits of detection(LLD) of 0.1 μg/kg for all analytes.At three fortification levels(1LLD，2LLD and 4LLD)，the spiked recoveries ranged from 94% to 108% with RSDs no more than 11.4% under within-laboratory reproducibility conditions.The method was simple，rapid，sensitive and accurate，and could meet the requirements for routine analysis and residue surveillance control.关键词：nitroimidazole;metabolites;residues;honey;liquid chromatography;quadruple/linear ion trap mass spectrometry
- 2452
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- 1112
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- 18
发布时间： - 摘要：Partial least squares(PLS) algorithm is one of the most common used chemometric algorithms，and is often combined with infrared and near infrared spectroscopy analysis.However，its regular implementation in a single-threaded way makes the modeling process severely ineffective when there are a great deal of models to built，or when there are iterative optimizations of the wavelength ranges and its preprocessing methods need to build an optimal model which contains thousands of samples，enormous data points，and uses a large number of principal components.To give an effective modeling method in this situation，this paper presented a novel parallel chemometric computation strategy which takes the Graphic Processing Unit(GPU) as computing devices，and then the parallel PLS algorithm，i.e.CUPLS，is implemented using the CUBLAS library.Finally，using a large near infrared spectroscopy(NIR) dataset as the test bed，a performance comparison experiment is conducted，and the results showed that the speed of the parallel algorithm is 42 times faster than that of the CPU-based implementation，which dramatically improves the efficiency of chemometric modeling algorithm.The proposed method shines a light on speeding up other chemometric algorithms with appropriate adoption.关键词：partial least squares(PLS);parallel computing;GPU;CUDA;spectral analysis
- 2265
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- 990
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- 3
发布时间： - 摘要：A method for the determination of migration levels of 7 N-nitrosamines and N-nitrosatable substances was developed using Sep-Pak AC2 connected to Dry cartridges and gas chromatography-tandem mass spectrometry.Its analytical tolerances for N-nitrosamines and N-nitrosatable substances in balloon were 1.25 μg/kg and 5.00 μg/kg,respectively.The average recoveries of 7 N-nitrosamines at a spiked concentration of 2.5 μg/kg ranged from 85% to 103% with RSDs（n=3） not more than 4.6%.N-nitrosodimethylamine（NDMA） and N-nitrosodiethylamine（NDEA） and their precursors were the most frequently nitrosamines and nitrosatable substances found in balloon samples,while N-nitrosomorpholine（NMOR）,N-nitrosopiperidine（NPIP） and N-nitrosodipropylamine（NDPA） and their precursors were not found in all balloon samples.The total migration values for 7 N-nitrosamines and N-nitrosatable substances in balloon samples were in the range of 0.036-0.964 mg/kg and 0.259-8.436 mg/kg,respectively.The risk exposure level of NDMA via oral intake from each balloon to children aged from 6 months to 4 years was grouped in the class of 0.010 mg/kg to 0.030 mg/kg body weight,which would bring high carcinogenic risk to children potentially.关键词：balloon;N-nitrosamine;N-nitrosatable substances;gas chromatography-tandem mass spectrometry;carcinogenic risk exposure
- 2539
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- 1300
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- 8
发布时间： - 摘要：The thermal decomposing curves of rutin in different heating speeds were obtained under dynamic conditions in nitrogen atmosphere,using non-isothermal thermogravimetric and derivative thermogravimetry methods（TG-DTG）.Four thermal analysis kinetic methods,e.g.Achar,Coats-Redfern,Kissinger and Ozawa method were used to speculate the probable mechanisms of thermal decomposing reaction and the kinetic parameters.The shelflives of rutin at sevral different temperatures were calculated by the kinetic parameters of first stage.With increase of the heating rate,the thermal decomposing tempreture of rutin rose.The most probable kinetic mechanisms of the three-stage thermal decomposition were nucleation and growth,three-dimensional diffusion,nucleation and growth,which correspond to Avrami-Erofeev Equation,Z.-L.-T.Equation and Avrami-Erofeev Equation,respectively.In accordance with the data of TG and Gaussian simulation,one molecule of rutin lost three oxygen atoms at the first stage of decomposition and lost ten oxygen atoms at the second stage while paraffins and one benzene ring were lost at the third stage.The shelflives of rutin at room temperature were about 15-2 years based on the apparent activation energy（Eα） and pre-exponential factor（A） of the first stage.关键词：rutin;TG-DTG;thermal decomposition;non-isothermal kinetics;Gaussian simulation
- 2032
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- 1110
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- 1
发布时间： - 摘要：A highly sensitive glucose biosensor was fabricated by immobilizing the glucose oxidase(GOD) on a new hybrid film of Au nanoparticles(Au NPs) and hydroxyapatite(HAp).The direct electrochemical behavior of GOD in the hybrid film was enhanced and a pair of well-defined，nearly reversible peaks appeared in deoxygenized pH 7.0 PBS due to the presence of AuNPs.The experimental results also showed that the peak current of dissolved oxygen at -0.8 V decreased with the addition of glucose due to the consumption of dissolved oxygen when the glucose was oxidized by GOD.The decreased reduction current of oxygen was linear with concentration of glucose in the range of 0.02-1.62 mmol/L with a sensitivity of 9.91 mA?mol-1?L and a detection limit of 5.0 μmol/L.The biosensor could be applied in the determination of glucose with high sensitivity and speediness.关键词：Au nanoparticles;hydroxyapatite;glucose oxidase;biosensor;glucose
- 2582
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- 1007
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- 3
发布时间： - 摘要：A fast,simple method for the determination of nicotine and its metabolites in human saliva was developed and validated by liquid chromatography-tandem mass spectrometry（LC-MS/MS）.Human saliva was collected with Salivette- collection kit and the quantification of analytes was achieved by using nicotinemethyl-d3,cotinine-methyl-d3 and trans-3′-hydroxycotinine-methyl-d3 as internal standard under atmosphere pressure chemical ionization（APCI） mode.The pretreatment of this method was simple and fast,and all analytes were eluted within 1 min.The relative standard deviations（RSDs） for nicotine and its two metabolites were between 0.29% and 4.0% and the recovery ranged from 94% to 104%.The linear correlations were above 0.998.Saliva,plasma and urine samples from 70 volunteers were collected and quantified by the described procedure.The classification of different smoking amount was also made using ada-boost based on the total concentration of salivary nicotine and its metabolites by a predicting accuracy of 76%.A good correlation of cotinine levels bewteen saliva and plasma（r=0.92）,saliva and urine（r=084） was found.The results showed that the cotinine in saliva has a longer half-life and becomes the most desirable biomarker for the evaluation of smoking exposure and nicotine uptake.关键词：LC-MS/MS;saliva;nicotine;cotinine;half-life;biomarker
- 2073
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- 959
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- 4
发布时间： - 摘要：A method was developed for the purification and detection of selenoprotein-P in human plasma.The sample was gradient eluted by two successive steps of affinity chromatography,i.e.,Heparin-Sepharose and Ni-Sepharose chromatography.The quality of the purified selenoprotein-P was detected by HG-AFS.The optimum gradient elution conditions were determined and the selenoprotein-P with a certain purity was obtained by SDS-PAGE.The recovery of the two steps of affinity chromatography reached up to 43.2%.The correlation coefficient of HG-AFS was 0.999 1，and the detection limit was 0.09 μg/L.The RSDs were 0.12% for within-day and 0.27% for inter-day.The recoveries were in the range of 95% - 104%.The proposed method was simple and sensitive,and the results obtained were accurate.关键词：selenoprotein-P;human plasma;heparin-sepharose;Ni-sepharose;affinity chromatography;HG-AFS
- 2409
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- 959
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- 1
发布时间： - 摘要：A method of microwave assistant extraction（MAE） combined with high performance liquid chromatography-tandem mass spectrometry（HPLC-MS/MS）was developed for the determination of 10 active components in Flos Lonicerae.The Flos Lonicerae samples were extracted by MAE,using ethanol-H2O（7∶3） as solvent with a solid-liquid ratio of 1∶30 at a temperature of 70 ℃.The extracts were separated on an Agilent Poroshell 120 SB-C18（100 mm × 2.1 mm,2.7 μm） column by gradient elution of 0.5% formic acid-acetonitrile.A triple quadrupole MS operating in multiple-reaction monitoring（MRM） mode with negative ion was used for the quantitative analysis of 10 active components.Under the optimized conditions,10 constituents in Flos Lonicerae were analyzed completely within 10 min.The linear ranges of 10 active components were in the range of 0.05-500 mg/L,with correlation coefficients no less than 0.996 9.The limits of detection and limits of quantitation were in the ranges of 69-4 413 μg/kg and 231-14 709 μg/kg,respectively.The spiked recoveries ranged from 94% to 105%.The method was applied in the determination of 10 active components in six different Flos Lonicerae samples with contents of 3.98-14 356.31 mg/kg.The proposed method was fast,accurate,and was suitable for the quality control of Flos Lonicerae.关键词：high performance liquid chromatography;tandem mass spectrometry;microwave assistant extraction;Flos Lonicerae;active components
- 2299
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- 1134
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- 5
发布时间： - 摘要：A gas chromatography-mass spectrometric(GC-MS) method was established for the simultaneous determination of 6 kinds of characteristic compounds,including furaneol,isoamyl isovalerate,maltol,menthol，ethyl maltol and anethole in cigarette.The sample was extracted with dichloromethane solution，concentrated with the rotary evaporation instrument,and analyzed by GC-MS.The conditions for sample preparation(e.g.sample volume,extraction solvent and extraction time) were optimized.Under the optimal conditions，the correlation coefficients of 6 analytes were higher than 0.998.The average spiked recoveries were in the range of 86%-92% with relative standard deviations(RSDs，n=6)of 4.7%-7.1%.The detection limits(S/N=3)and quantitation limits(S/N=10) were in the range of 0.014 7-0.074 6 μg/g and 0.048 9-0.248 8 μg/g，respectively.The method showed good extraction efficiency,high sensitivity and good reproducibility，and was suitable for the simultaneous detection of 6 compounds in cigarette flavoring.The results also indicated that the method could be used for the evaluation of the uniformity of cigarette flavoring on the processing line through determination of the characteristic compound contents in samples.关键词：gas chromatography-mass spectrometry(GC-MS);cigarette;characteristic compound;flavoring uniformity;determination method
- 2048
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- 1173
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- 5
发布时间： - 摘要：A kind of silica-coated magnetic nanomaterials modified with 1-octyl-3-methylimidazolium hexafluorophosphate（［OMIM］PF6） was prepared,and characterized by scanning electron microscope（SEM）,Fourier transform infrared spectroscopy（FT-IR）,vibrating sample magnetometer（VSM） and thermogravimetric analyzer（TGA）.The synthetic material（Fe3O4-SiO2-IL） showed a good acid resistance.The adsorption behavior of cadmium ion onto Fe3O4-SiO2-IL was tested,and it was found that the equilibrium adsorption followed Langmuir isotherms well.Based on this,a new method for separation and preconcentration of Cd2+ in aqueous solution was developed by using modified silica-coated magnetic nanoparticle as the sorbent and flame atomic absorption spectrometry（FAAS） as detector.Ｅffects of some factors on recovery of Cd2+ were investigated.The optimum conditions were as the follows：pH 6.0;eluent：1 mol/L HCl;oscillation time：10 min;standing time：20 min.Under the optimized conditions,the limit of detection（LOD） for Cd2+ was 0.2 μg/L,and relative standard deviation（RSD,n=6） for 15 μg/L Cd2+ was 2.5%.The proposed method was applied in the determination of Cd2+ in river and lake water with spiked recoveries of 84%-100%.关键词：magnetic nanomaterials;ionic liquid;cadmium ion;water sample
- 2393
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- 1067
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- 8
发布时间： - 摘要：Based on the synergic effect of multi-walled carbon nanotubes(CNTs) and thionine(Th)，a novel hydrogen peroxide electrode(HRP/GA-Th/CNTs/GC) was fabricated by immobilizing horseradish peroxidase(HRP) onto the thionine(Th) /multi-walled carbon nanotubes modified electrode via glutaradehyde(GA) cross-linking.The introduction of CNTs into the electrode is helpful for the further immobilization of Th and the catalysis to H2O2.Furthermore，Th immobilized on CNTs by electrostatic adsorption not only can transfer electrons between the electrode and the redox activity center of the enzyme，but also can enable amine group(—NH2) in Th to provide convenience for the immobilization of HRP enzyme via glutaradehyde cross-linking.Additionally，effects of various experimental parameters on H2O2 sensing，including applied potential，pH value and electroactive interferent，were investigated.At an optimal potential of -0.3 V，the current response of the biosensor in phosphate buffer(pH 7.0) was linear with H2O2 concentration from 5 μmol?L-1 to 40 μmol?L-1，with a good detection limit(0.3 μmol?L-1)，a short response time(within 5 s) and a good anti-interferent ability.关键词：multi-walled carbon nanotubes;horseradish peroxidase;thionine;synergistic effect;hydrogen peroxide;biosensor
- 2281
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- 1011
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- 4
发布时间： - 摘要：A high performance liquid chromatography-tandem mass spectrometric（HPLC-MS/MS） method was developed for the determination of tralomethrin residues in ten kinds of plant-based foods,including vegetables,fruits,tea and bean.The samples were extracted with ethyl acetate for vegetables,fruits,tea,and acetonitrile for bean.The extract was concentrated and purified by solid phase extraction（SPE）.Chromatographic separation was achieved by HPLC on an Agilent ZORBAX Eclipse XDB C18 chromatographic column using methanol-0.1% formic acid with 10 mmol/L ammonium acetate as mobile phase by gradient elution.The detection was performed by tandem mass spectrometry under multiple reaction monitoring mode and the quantification by the matrix-matched external standard method.Results showed that the calibration curve of tralomethrin was linear in the range of 20-1 000 μg/L with a correlation coefficient of 0.999 8.The recoveries for tralomethrin at three spiked levels（0.01,0.02,0.1 mg/kg for cereals,teas and beans and 0.005,0.01,0.05 mg/kg for fruits and vegetables） were between 75% and 92% with relative standard deviations（RSDs,n=6） of 4.0%-126%.The limits of quantitation（S/N≥ 10） were 0.01 mg/kg for cereals,teas and beans,and 0.005 mg/kg for fruits and vegetables.The method can be used to separate and identify deltamethrin and two diastereoisomers of tralomethrin while the gas chromatography（GC） with electron capture detector（ECD） and MS detector,which are routinely applied in the analysis of pyrethroid pesticides in foods,but cannot distinguish these two pesticides.关键词：high performance liquid chromatography-tandem mass spectrometry;tralomethrin;food;determination
- 2594
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- 1021
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- 2
发布时间： - 摘要：A novel fluorescent sensor，8-(2-(octadecylamino)acetylamino)quinoline(AQZ-18)，was synthesized for sensing Zn2+.Two fluorescence peaks at 320 nm and 505 nm were observed in the solution of AQZ-18，non-ionic surfactant OP-10 and Zn2+.The shorter wavelength peak arised from autofluorescent OP-10 kept almost unchanged，while the longer wavelength peak produced by AQZ-18 increased gradually with increase of Zn2+ concentrations.Base on this， a new ratiometric method was established by measuring the ratio variations of fluorescence intensities in the two regions.The 1∶1 ground state complex between Zn2+ and AQZ-18 was formed，and the apparent association constant was obtained to be 1.1×106 L/mol.Some common metal ions had no obvious interference for AQZ-18 to detect Zn2+.The ratio of two fluorescence intensities presented a linear relationship with concentration of Zn2+ in the range of 0-1.1×10-5 mol/L(r2=0.996 2)，with a detection limit of 55 nmol/L.The method could be used for the determination of Zn2+ in water samples.关键词：detection;fluorescence;ratiometric;Zn2+;surfactant;solubilization
- 2292
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- 3
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- 1
发布时间： - 摘要：An electrochemical immunosensor was developed for the ultrasensitive measurement of α-fetoprotein based on electrochemical stripping analysis of silver nanoparticles catalytically deposited by nanogold labels.The immunosensor was prepared by covalently immobilizing capture antibodies with glutaraldehyde（GA） on chitosan multi wall carbon nanotubes modified glassy carbon electrodes.Through a sandwich type immunoreaction,antibody-functionalized AuNPs were captured onto the immunosensor surface,and further induced a subsequent silver deposition.The deposited AgNPs were then measured directly by anodic stripping analysis in KCl solution.Under the optimal conditions,the calibration curve was linear over α-fetoprotein concentration in the range of 0.02-200 μg/L,the linear regression equation is ΔI=-0.13-0.11c（μg/L）（r=0.992 8）.The detection limit is 8 ng/L.The electrochemical immunosensor was applied in the determination of α-fetoprotein in three serum samples.The relative standard deviation is no more than 6.1%.The determination result is identical with the result of electrogenerated chemiluminescence method.The sensor showed acceptable reproducibility,stability and accuracy,indicating a promising potential in clinical diagnose.关键词：α-fetoprotein;silver deposition;electrochemical stripping analysis;immunosensor
- 2411
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- 1065
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- 2
发布时间： - 摘要：A comprehensive analytical method for the determination of bisphenol A,octylphenol and nonylphenol in skin care cosmetics was developed using ultra performance liquid chromatography with tandem mass spectrometry（UPLC-MS/MS）.The homogenized sample was extracted with methylene chloride.Sample concentration and purification were performed on an OASIS NH2 solid phase extraction cartridge.The separation of 4 compounds was carried out on a Waters UPLC BEH C18 column by gradient elution with methanol-0.5% NH3?H2O as mobile phase.The analytes were detected under multiple reaction monitoring（MRM） with electrospry ionization in negative ion mode（ESI-）,identified with retention time and ion ratio,and quantified by the external standard method.Under the optimal conditions，the separation of analytes was performed within 5 min.The calibration curves for four compounds were linear in the range of 0.5-50.0 μg/L with correlation coefficients more than 0.999.The quantitation limits were 0.5 μg/kg．The mean recoveries for four compounds in skin water and skin cream samples at three spiked concentration levels of 0.5，1.0，10.0 μg/kg were in the range of 80%-96% with RSDs（n=6） less than 15%．This method is accurate,simple and rapid,and is suitable for the inspection of bisphenol A,octylphenol and nonylphenol in skin care cosmetics.关键词：skin care cosmetics;SPE;UPLC-MS/MS;bisphenol A;octylphenol;nonylphenol
- 2620
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- 1250
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- 7
发布时间： - 摘要：A PABSA/GN/GCE composite-modified electrode was fabricated by using a graphene nanosheets（GN） modified glassy carbon electrode（GCE）electropolymerized with p-aminobenzene sulfonic acid（PABSA）.The electrochemical behaviors of uric acid（UA） and ascorbic acid（AA） on the nanocomposites-modified electrode were investigated.Compared with PABSA/GCE and GN/GCE,the PABSA/GN/GCE improved the resolution and the sensitivity for the determination of UA in the presence of AA.In 0.1 mol/L phosphate buffer solution（pH 7.0）,a peak to peak separation of 344 mV was observed,which enabled the selective determination of UA.The peak currents obtained from DPV were linearly related to concentrations of UA in the range of 1.0×10-7-8.0×10-4 mol/L.The detection limit was 4.5×10-8 mol/L.The nanocomposites-modified electrode was adopted for the detection of UA in the human urine with satisfactory result.关键词：p-aminobenzene sulfonic acid;graphene nanosheets;modified electrode;selective determination;uric acid(UA);ascorbic acid(AA)
- 2140
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- 940
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- 4
发布时间： - 摘要：An on-line improved ultraviolet detection method was developed for the determination of melamine in various samples by using water plug coupled with field-enhanced sample injection and capillary zone electrophoresis technique（FESI-CZE）.The optimal conditions were as follows:water plug containing 60% water and 40% acetonitrile,water injection time:200 s,running buffer:120 mmol/L NaH2PO4（pH 2.2）- 10% methanol,sample matrix:0.10 mmol/L NaH2PO4（pH 2.2）- 20% acetonitrile,sample injection voltage:20 kV,sample injection time:80 s,separation voltage:20 kV.Under the optimum conditions,the calibration curve was linear in the range of 10-1 000 μg/L.Compared with that of the traditional CZE method,the sensitivity of FESI-CZE method was improved about 800 times and the LODs(S/N=3) was decreased from 2.0 mg/L to 2.5 μg/L.This method was used to detect the melamine in various samples with recoveries of 98%-106% and RSDs（n=4）no more than 5.1%.This method is sensitive,reliable,economic and pretreatment free for complex samples,and it could overcome the shortcoming of low sensibility with ultraviolet detector.关键词：ultraviolet detector;capillary zone electrophoresis;field-enhanced sample injection;melamine
- 2097
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- 969
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- 0
发布时间： - 摘要：During the determination of molecular weight calibration curve of thymosin by size exclusion chromatography（SEC）,the acetonitrile ratio in mobile phase performanced significant influence on not only the retention time of four proteins（e.g.ribonuclease A,human insulin,thymosin α1 and somatostatin）,but also the linearity of molecular weight calibration curve.The best linearity was obtained at the ratio of acetonitrile by 75%,with a calibration equation of y=-3.138 6x+21.724 and a linear correlation coefficient(r2)of 0.988 5.In that condition,the theoretical plate numbers of four proteins were between 45 783 and 63 345,tailing factors were between 0.96 and 1.18,and resolutions were between 3.52 and 8.82.The established LC method to determine molecular weight calibration curve of thymosin by SEC was proved to have excellent separation and good linearity.Thus it can be used to detect the high molecular weight substance in thymosin preparation.关键词：size exclusion chromatography;molecular weight calibration curve;thymosin
- 1937
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- 989
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- 1
发布时间： - 摘要：The self-assembled monolayers（SAMs） of 4,4′-bis（methanethiol）biphenyl（MTP） and 6-thioctic acid（TA） were covalently combined on to a bare gold electrode to make self-assembled monolayers（TA+MTP/Au SAMs）.It was then dipped into gold nanoparticles solution for a certain time to prepare the AuNPs/MTP+TA/Au electrode.The electrochemical behaviors of the modified electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy.The results showed that the acidity variation of the electrode surface had an important influence on the electron transfer.The preparation conditions,determination conditions and anti-interference ability of glucose sensor were discussed,which showed that it was necessary to further study the microstructure and microenvironment of the modified electrode.关键词：electrochemistry;alkanethiols;self-assembled monolayers;impedance spectroscopy;cyclic voltammetry
- 2039
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- 1088
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- 0
发布时间： - 摘要：A novel flow-injection chemiluminescence method was developed for the determination of paracetamol,which was based on the chemiluminescence reaction between paracetamol and hydroxy free radical produced by Fe3+ and H2O2 solution in the presence of dichlorofluorescein as energy transfer in the chemiluminescence system．Various factors influencing the chemiluminescence system were investigated and the possible mechanism was also discussed.Under the optimum conditions,the linear range for the determination of paracetamol was 8.0×10-8-5.0×10-5 mol/L with a detection limit（S/N=3） of 5.0×10-9 mol/L,the relative standard deviation（RSD,n=9） was 2.2% for 3.5×10-6 mol/L paracetamol solution.The method was successfully applied in the determination of paracetamol in pharmaceutical sample.关键词：flow-injection;chemiluminescence;dichlorofluorescein;paracetamol
- 1937
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- 873
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- 2
发布时间： - 摘要：A chiral capillary column with gas chromatographic method was developed for the determination of three isomers of 2,3-butanediol,e.g.（2S,3S）-（+）-butanediol（d-BT for short），（2R,3R）-（-）-butanediol（l-BT for short）and meso-（R,S）-butanediol（meso-BT for short）,in liquor sample.The samples were extracted via vibration with ethyl acetate and methanol（4∶1） mixed solution.The extract was purified with graphitization carbon black column using solid phase extraction device.The 2,3-butanediol isomers were separated on a CP-Chirasil-DEX CB capillary column,and detected with flame ionization detector.The quantification of three isomers was performed by the external standard method.The calibration curves of d-BT,l-BT and meso-BT were linear in the ranges of 10-75,60-300,20-100 mg/L,respectively,with correlation coefficients of 0.999 1，0.999 6 and 0.999 9,respectively.The spiked recoveries of three butanediol isomers were 90%-113% in wine with RSDs（n=6）of 1.1%-7.2%,and 96%-99% in spirit with RSDs（n=6）of 1.7%-3.8%,respectively.The detection limit was 1.0 mg/L.The method was applied in the determinations of d-BT,l-BT and meso-BT in wine samples and sipirit samples before and after irradiated by Cobalt 60-gamma rays with irradiation dose of 10 kGy.The results showed that d-BT was detected in spirit samples after irradiation,but no obvious change of d-BT content occured in red wine,which could provide an evidence on whether the sipirit samples were irradiated or not.关键词：2,3-butanediol;isomers;wine;gas chromatography;irradiation
- 2006
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- 1262
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- 3
发布时间： - 摘要：With their high chiral recognition to a broad range of chiral compounds,polysaccharide derivatives based chiral stationary phases（CSPs） have been regarded as the most powerful CSPs in the direct resolution of enantiomers by HPLC.Since there are no chemical linkages between the polysaccharide derivatives and the supports,the coating-type CSPs exhibit some disadvantages such like poor solvent durability and rather limited mobile phase selection.With broadened mobile phase selection and improved stability,immobilizing-type polysaccharide-based CSPs overcome the disadvantages of the coated ones,and have become the hot topics in chiral separation in recent years. In this paper,five immobilization methods of the polysaccharide based CSPs,including the bifunctional reagent method,chemical bonding of the amylose derivative via an activated chain end,radical polymerization,photoirradiation and intermolecular polycondensation,were introduced and compared,Furthermore,the further developments of those CSPs are prospected.关键词：polysaccharide derivatives;chiral stationary phases;immobilization;development progress;review
- 1930
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- 1046
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- 9
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