最新刊期
卷 35 ， 期 6 ， 2016
- 摘要：Highly efficient enrichment is the key for rapid analysis and detection of microbiological aerosol.Herein,a poly(dimethylsiloxane)(PDMS) microfluidic chip which has a single spiral channel was developed,and the chip was used for Vibrio parahaemolyticus enrichment.The characteristic of this chip is that it has a single spiral channel which contains a herringbone structure with uniform distribution.During different enrichment times,the number of captured bacteria by microfluidic chip is far bigger than that by the traditional sediment method.Moreover,the chip shows more enrichment advantages when capturing microbiological aerosol in low concentration.This excellent enrichment ability,on one hand,benefits from the unique spiral channel design which can put greater centrifugal force to the microbiological aerosol.On the other hand,the herringbone structures design endows the chip larger surface specific area increasing the contact probability between microbiological aerosol and chip.In addition,a similar spiral microfluidic chip without herringbone structures was also designed.The results validated the contribution of herringbone structures to the enrichment efficiency. With the advantages of delicate design and fabrication,portability and high enrichment capacity,this microfluidic chip shows a great application potential in field like aquatic products processing industry.关键词：single spiral microfluidic chip;Vibrio parahaemolyticus;enrichment;herringbone structure
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发布时间： -
Quantitative Analysis of 6 Components in Hebra Sarcandrae by Ultra Performance Liquid Chromatography
摘要：An ultra performance liquid chromatographic(UPLC) method was developed to quantitatively analyze six components,ie.,neochlorogenic,chlorogenic acid,4 dicaffeoylquinic acid,caffeic acid,rosmarinic acid and isofraxidin in Hebra Sarcandrae.The UPLC analysis was carried out on a Waters Acquity BEH C18 column(2.1 mm×50 mm，1.7 μm) by gradient elution with acetonitrile and water(both containing 0.1% formic acid) as mobile phase at a flow rate of 0.5 mL?min-1.The column temperature was maintained at 35 ℃ and the detection wavelength was set at 330 nm.Isofraxidin was used as an internal reference substance to get the average relative correction factors(RCFs) of the other 5 components(neochlorogenic,chlorogenic acid,4-dicaffeoylquinic acid,caffeic acid,rosmarinic acid),and chromatographic column,mobile phase,flow rate,column temperature were investigated to validate the durability of the achieved RCFs.The contents of 6 components were determined by both quantitative analysis of multicomponents by single marker(QAMS) and external standard method(ESM),and the quantitative results were compared between the two methods by using paired t-test.The results showed that the linear ranges for neochlorogenic,chlorogenic acid,4-dicaffeoylquinic acid,caffeic acid and,rosmarinic acid and isofraxidin were 0.522 0-26.09，1.482-74.13，0.591 0-29.49，0.632 5-31.29，2.612-130.5，0.970 4-48.73 μg?mL-1(r≥0.999 7),respectively.The RSD values(n=6) of precision,reproducibility,and sample stability were not more than 1.9%.The average recoveries of 6 components were between 98.6% and 101.5% with RSDs not more than 1.9%.The achieved RCFs are good(RSD＜5.0%).There is no significant difference in the contents obtained by the two methods with P values greater than 0.05,so both of the methods could be applied in the simultaneous determination of five caffeoyl derivatives and one coumarin in Hebra Sarcandrae.关键词：Hebra Sarcandrae;ultra performance liquid chromatography(UPLC);external standard method;quantitative analysis of multicomponents by single marker;quantitative analysis;caffeoyl derivatives;coumarin- 1840
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- 1036
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发布时间： - 摘要：A sensitive mass spectrometric approach was developed for the detection of trace lead in water.The microwave plasma torch(MPT) was used as the ion source for direct analysis of water samples without any pretreatments.Aqueous samples were introduced in the plasma through the central cube of the MPT after nebulization and dying,the generated ions were detected by a homemade quadrupole mass spectrometer(Q-MS).The quantitative results showed that the limit of detection(LOD) was at the level of 20 ng/L,and the linear range was 200-1 000 ng/L with RSD of 5.3%.These quantitative indexes were better than the results from the international commercial linear ion trap mass spectrometer(LTQ-MS) under the same MPT working conditions.However,the characteristical mass spectra obtained on MPT-Q-MS were simpler and easier to be assigned without further MSn experiments,thus MPT coupled with Q-MS will be suitable for the development of the portable analysis instrument,and have the potential applications in environmental controlling and drinking water detection.关键词：microwave plasma torch;mass spectrometry;lead;water
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- 1027
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- 1
发布时间： - 摘要：A new approach was proposed for the determination of phenol in an unknown mixture by using three-dimension fluorescence coupled with second-order calibration methods based on rank annihilation factor analysis(RAFA),generalized rank annihilation factor analysis(GRAFA) and alternating trilinear decomposition(ATLD) algorithms,respectively.Fluorescence spectra were detected at consecutive time points in excitation range of 240-280 nm and emission range of 280-360 nm for each sample.Therefore,a three-way response data array was established and analyzed by second-order calibration method of trilinear decomposition.When the component number of sample was set to 2,the obtained average recoveries(AR) of phenol were 101.6%,115.6%,101.9%,and the root-mean-squared errors of prediction(RMSEP) for RAFA,GRAFA and ATLD were 0.33,1.18 and 0.15,respectively.When the component number of sample was set to 3,the obtained average recoveries of phenol were 134.2%,133.9%,107.1%,and the root-mean-squared errors of prediction for RAFA,GRAFA and ATLD were 1.61,1.80 and 0.51,respectively.The proposed method was applied in the determination of phenol in actual water samples with satisfactory results,and the associated verified experiments showed that ATLD is superior to RAFA and GRAFA.关键词：phenol;three-dimensional fluorescence;second-order calibration;rank annihilation factor analysis(RAFA);generalized rank annihilation factor analysis(GRAFA);alternating trilinear decomposition(ATLD)
- 1931
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- 1172
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- 1
发布时间： - 摘要：A new reactor termed as liquid glow discharge(LGD) was modified and designed according to the principle and characteristic of electrolyte cathode glow discharge(ELCAD) for the determination of cadmium in aqueous solution.The effects of discharge voltage and solution concentration on the discharge stability,signal strength,sensitivity and detection limit were investigated in detail.The detection limits of present work were compared with the values measured by ELCAD.The results showed that with the increase of discharge voltage from 600 V to 720 V,the electronic temperatures were increased from 2 000 K to 3 300 K,electron densities were decreased from 2.47×1016 cm-3 to 1.77×1016 cm-3,emission intensities were enhanced and the sensitivity of the method for cadmium was increased with limits of detection of 1.22-2.95 mg/L.All results demonstrated that the LGD-AES is a promising technique in detection of metal elements in aqueous soltion because of small size of discharge equipment,low energy consumption,high discharge stability,small background spectrum interference and high sensitivity.关键词：electrolyte cathode glow discharge(ELCAD);liquid glow discharge(LGD);plasma;atomic emission spectrometry(AES);cadmium
- 1896
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- 1019
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- 6
发布时间： - 摘要：Based on the incremental regularity of γ-(Glu-Cys)n-Gly series compouds,the qualitative and quantitative analyses of peptides were achieved by using Trap-MS ion screening function.The thiol groups(—SH) of PC2-PC6 could react with the monobromobimane(mBBr) to get polypeptide derivatives with fluorescent signal,and the reaction proportion of PCs and mBBr was 1∶1 identified by Trap-MS,which also showed that the intensity of the polypeptide derivatives was stable in 1 week.HPLC-Trap-MS and the chromatographic conditions of HPLC were optimized.The ion extraction results showed that the method was rapid and accurate,and the compound separation effect was obvious,PC2,PC3,PC4,PC5 and PC6 had wide linear ranges with linear correlation coefficients more than 0.999,and the detection limits were 0.13,0.02,0.17,0.39,0.82 mg/L,respectively.The recoveries were in the range of 89.0%-99.5%,and the method was reproducible with RSDs less than 3.5%.The quantitative analysis under the double detectors of the fluorescence and the mass spectrum could be realized by the fluorescence labeling and Trap-MS screening of peptide compound,which could be used to analyse polypeptide compounds rapidly and accurately.The content of polypeptide in alga was detected after being induced by Zn and Cd,and the results showed that the polypeptide had an induced response to the metal,in which the small molecular peptide changed obviously,the induced response of peptide to the heavy metal was delayed with the increase of the carbon chain.关键词：polypeptide;fluorescence labeling;HPLC;mass spectrometric characterization;ion extraction
- 1747
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- 1019
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发布时间： - 摘要：Hydrophilic molecularly imprinted polymers(MIPs)were synthesized via the bulk polymerization with α-1-allyl-2-N-acetyl glucosamine as novel water miscible functional monomer and N,N′-methylenebisacrylamide as cross-linker,which introduce the abundance of hydrophilic groups into MIPs.The photographs of the dispersion properties and water contact angles demonstrated that MIPs presented an excellent hydrophilicity.The binding experiments indicated that MIPs exhibited an excellent imprinting effect and a high selectivity to gastrodin.Under the optimum molecular imprinted solid phase extraction(SPE) conditions,MIPs could be used as an adsorbent phase to enrich gastrodin from gastrodia elata.The method showed excellent recoveries(90.4%-97.1%)and precision(3.3%-5.2%,n=5).Based on the new type of hydrophilic functional monomer, a molecularly imprinted solid phase extraction sample pretreatment method for glycosidic substance was established.关键词：hydrophilic molecularly imprinted polymers;gastrodin;adsorption performance;solid phase extraction(SPE)
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发布时间： - 摘要：A colorimetric method was developed to determine chromium ions(Cr3+) in water,by using 13 nm diameter gold nanoparticles(AuNPs) synthesized by the citrate-mediated reduction of HAuCl4 as the transducer component for signaling color change,and 3-amino-5-mercapto-1,2,4-triazole(AMT) as the recognition element for Cr3+.AMT was assembled onto the surface of AuNPs to form a stable water-soluble AMT-AuNPs compound.In the presence of Cr3+,the specific binding of AMT and Cr3+ in solution could lead to the aggregation of AMT-AuNPs and a red shift of the maximum absorption wavelength,simultaneously producing an obvious color change from red to blue-purple,which could be used for Cr3+ visual detection.Under the optimized conditions(concentration of AMT:0.8 μmol/L；pH 7.0),the detection limit(3σ) of the method could be as low as 100 nmol/L for Cr3+ with linear detection range of 6-14 μmol/L,and there was almost no interference from other metal ions.With the advantages of fast response(5 min)，simplicity of preparation and manipulation,and no need of reading device,the presented method is promising in the application of on-site fast detection of Cr3+ in water.关键词：Cr3+ detection;3-amino-5-mercapto-1,2,4-triazole;gold nanoparticles;colorimetric sensor;water
- 2092
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- 1050
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- 0
发布时间： - 摘要：A simple and efficient online sample pre-concentration method composed of large volume sample injection(LVSI)-reduced electric field sweeping(REFS) and microemulsion electrokinetic chromatography(MEEKC) was developed for the determination of glucocorticoids(prednisone,hydrocortisone,prednisolone and betamethasone) in cosmetics.The microemulsion background buffer was composed of 2.4%dodecyl sodium sulfate,6.6% butanol,0.6%octane and 30 mmol/L borate buffer(pH 8.2).The separation voltage was 9.6 kV and the sample was injected at 12.3 kPa for 95 s.The detection wavelength was set at 230 nm.Under the optimum conditions，the enrichment factors ranged from 853 to 933.The calibration curves were linear in the concentration of 0.015-14 mg/L.The limits of detection(S/N=3) were in the range of 4-8 μg/L.The developed method was used to analyze corticosteroids in cosmetics with recoveries of 93.7%-103.8%and RSDs(n=5) not more than 4.4%.关键词：microemulsion electrokinetic chromatography;online pre-concentration;large volume sample injection;sweeping;cosmetic;glucocorticoid
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发布时间： - 摘要：A gas chromatography-mass spectrometry(GC-MS) combined with retention index(RI) method was developed for the analysis of volatile oils in Rhizoma Alpiniae Officinarum extracted by steam distillation(SD),ultrasonic assisted solvent extraction(UAE) and subcritical fluid extraction(SFE).51,46 and 60 volatile components in the oils extracted by the three above-mentioned methods were identified,respectively.Meanwhile,each of them was quantified by area normalization method.The results indicated that the content of the index constituent,i.e.,1,8-cineole,the content by SD was similar to that by SFE,and higher than that by UAE.Although UAE was time-saving and less energy consumption,the oil quality was poorer due to the use of organic solvents hard to remove.In addition,some constituents could be gained by SFE but not by SD,such as 2-hydroxycineole,diarylheptanoids and etc.On one hand,the relative contents of high boiling components obtained by SFE,like β-caryophyllene,α-caryophyllene,α-farnesene and γ-cadinene,were higher than the others.On another hand,the relative contents of low boiling components obtained by SD,like α-pinene,camphene,β-pinene,limonene,camphor and α-terpineol,were the highest of three.In conclusion,volatile oil components by different extraction methods from the same batch of materials were proved broadly similar,but there were some differences in composition and component ratio.Therefore,development and utilization of different extraction methods must be selected according to the functional requirements of products.关键词：volatile oil;gas chromatography-mass spectrometry(GC-MS);steam distillation;ultrasonic assisted solvent extraction;subcritical fluid extraction
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- 9
发布时间： - 摘要：A solid phase exaction coupled with ultra high performance liquid chromatography-tandem mass spectrometric(UPLC-MS/MS) method was developed for the simultaneous determination of 19 pesticides in strawberry.After extraction with acetonitrile,purification with NH2 SPE cartridges and dissolution with methanol,the analytes were analyzed by UPLC-MS/MS on an Agilent Proshell120 EC-C18 column with a mixture of 0.1% formic acid-acetonitrile as mobile phase by gradient elution.The mass spectrometer was operated in multiple reactions monitoring(MRM) mode in positive mode.The purifying effects of 6 pretreatment methods were optimized by UPLC-Q-TOF.Matrix effects of real strawberries were studied.The limits of quantitation(LOQs),which were determined by adding standard solution to pesticide free strawberry samples,were 0.001 mg/kg for mandipropamid,bifenazate,picoxystrobin and pyraclostrobin and 0.01 mg/kg for the others.Good linearities were obtained for 19 pesticides in the concentration range of 0.000 5-1.0 mg/L with correlation coefficients more than 0.999.The fortified recoveries at low,intermediate and high concentration levels were in the range of 77.3%-100.3%,with relative standard deviations(RSDs) not more than 12.3%.False positive results were avoided effectively due to the methods good ablity of resistence matrix interference.All the above observations indicated that the established method was simple,efficient and sensitive,and was suitable for the determination of 19 pesticides in strawberry.关键词：ultra high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS);solid-phase extraction(SPE);pesticides;residue;strawberry设施草莓(Fragaria ananassa Duchesne)
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发布时间： - 摘要：High-precision determination of mercury isotope ratios using multi-collector inductively coupled plasma mass spectrometry(MC-ICP-MS) requires high quality of sample pretreatment.Different kinds of pretreatment methods developed for liquid,solid and gaseous samples may result in certain systematic errors.This study aimed at unifying the pretreatment techniques of different kinds of environmental samples.Mercury in samples was enriched and transformed into absorbable solid state and then adsorbed onto a solid carrier,including gaseous elemental mercury in gaseous samples enriched with gold column,dissolved gaseous mercury and total mercury in liquid samples enriched with purge and trap method and particulate mercury in the atmosphere collected with membrane filter method.Solid sample was combusted in a tube furnace.An acidic absorbing solution with potassium permanganate was adopted to absorb Hg2+that was oxidized from Hg0 produced in the combustion.Finally,the absorbing solution was analyzed by MC-ICP-MS.The parameters,including oxygen gas flow rate,volume of absorbing solution and concentration of potassium permanganate,were optimized.Method blank,recovery and precision of the method were investigated.The established method was applied in the sample pretreatments of gaseous elemental mercury and particulate mercury in the atmosphere,dissolved gaseous mercury in seawater,total mercury in rain and soil.The isotopic compositions of mercury in the samples were analyzed and discussed.关键词：combustion-trapping;environmental samples;mercury isotope;pretreatment
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发布时间： - 摘要：Cancer antigen-153(CA-153) was very significant specific tumor marker.An Au nanoparticles/graphene oxide(Au NPs/GO)-based electrochemical immunosensing platform was fabricated for the sensitive detection of CA-153 by the sandwich immunoassay protocol.Au NPs/GO composite material was used to modify the glassy carbon electrode.CA-153 antibody was anchored on the surface of Au NPs by the absorbtion of Au NPs and CA-153 antibody.Bovine Serum Albumin(BSA) was used to block possible remaining active sites of nanomaterials and avoid the nonspecific adsorption.AuAg cube nanomaterial available to catalyze the reduction of hydrogen peroxide was used to lable antibody(Ab2).The electrochemical signals derived from the carried AuAg cube toward the reduction of H2O2 using the thionine as electron mediator,and were measured by differential pulse voltammetry.Under the optimized experimental conditions,the linear range and the detection limit(S/N=3) of CA-153 immunosensor were 2.0×10-5-100 U/mL and 7.0×10-6 U/mL,respectively.The proposed method was applied in the detection of CA-153 in spiked human serum samples with recoveries of 92.2%-110.2% and RSD not more than 8.7%.关键词：electrochemical immunosensor;AuAg nanoparticles;Au nanoparticle/graphene oxide composites;cancer antigen-153
- 1966
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- 984
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- 1
发布时间： - 摘要：A comprehensive method was developed and optimized for the simultaneous analysis of sulfonamides,quinolones,steroid hormones and tetracycline by ultra performance liquid chromatography-mass spectrometry(UPLC-MS).The veterinary drugs in milk samples were extracted with 5% acetic acid-acetonitrile solution,and then the mixture was centrifuged.The supernatant was purified with an HLB solid phase extraction column,and analysed by UPLC-MS and quantified by the external standard method.Average recoveries of 25 veterinary drugs at three spiked levels ranged from 61.6% to 119.2% with relative standard deviations(RSDs) of 2.5%-13.4%.The method limits of detection(LOD) for target compounds were in the range of 0.5-2.0 μg/kg.关键词：ultra performance liquid chromatography-mass spectrometry(UPLC-MS);milk;veterinary drugs residues;sulfonamides;quinolones;steroid hormones;tetracycline
- 1904
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- 1380
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发布时间： - 摘要：A selective gas chromatography tandem triple quadrupole mass spectrometry was used to detect nine volatile nitrosamines,including N-nitrosodimethylamine(NDMA),N-nitrosodiethylamine(NDEA),N-nitrosomethylethylamine(NMEA),N-nitrosodipropylamine(NDPA),N-nitrosopyrrolidine(NPYR),N-nitrosopiperidine(NPIP),N-nitrosodibutylamine(NDBA),N-nitrosomorpholine(NMOR),N-nitrosodiphenylamine(NDPhA) in local sausage on sale by using QuEChERS sample pretreatment.The calibration curves of nine volatile nitrosamines were linear in the range of 0.25-200 μg/L,with detection limits of 0.01-0.10 μg/kg.The recoveries were in the range of 90.7%-116.0% at three spiked concentration levels in sample,with relative standard deviations(RSDs) of 1.8%-14.0%.The method was applied in the detection of local sausage on sale,and seven volatile nitrosamines were all detected.The detection rates of NDMA，NMOR，NPYR，NDPA were higher than that of the others.The contents of total volatile nitrosamines were in the range of 1.85-13.44 μg/kg.The developed method was simple,rapid,sensitive and accurate.关键词：volatile nitrosamines;gas chromatography tandem triple quadrupole mass spectrometry;local sausage
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- 9
发布时间： - 摘要：A simple and sensitive electrochemical aptamer sensor was developed for the determination of environmental hormone bisphenol A(BPA).Nanoporous Au(NP-Au) was first deposited on the glassy carbon electrode(GCE) surface by electrochemical deposition,followed by one-step electropolymerization synthesis of polythionine(PTH) and aptamer(APT).The PTH was used as a redox electrochemical probe and the immobilization matrix for APT.Then,BSA as a blocking agent was used to prevent non-specific adsorption.The electrochemical behavior of the GCE/NP-Au/PTH+APT/BSA aptamer sensor was studied by DPV method.The GCE/NP-Au/PTH+APT/BSA sensor showed a good linear range of 10.0 fg/mL-1.0 ng/mL for BPA with a detection limit of 5.3 fg/mL.The GCE/PTH+APT/BSA sensor as reference showed a linear range of 10.0 fg/mL-1.0 ng/mL for BPA with a detection limit of 90 fg/mL.The experimental results showed that the introduction of NP-Au could effectively improve the sensitivity.The GCE/NP-Au/PTH+APT/BSA sensor had the advantages of high selectivity and low detection limit.关键词：bisphenol A;aptamer;sensor;nanoporous Au;polythionine
- 1942
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- 1022
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- 1
发布时间： - 摘要：Halloysite nanotubes(HNTs) were modified with silane coupling agent 3-triethoxysilylpropylamine(APTS) and their sorption behavior for methylene blue(MB) was investigated.Halloysite nanotubes composites before and after modification were characterized with Fourier transform infrared spectrometer(FTIR) and X-ray diffractometer(XRD).The sorption behavior of the modified halloysite nanotubes for methylene blue was studied as a function of contact time and temperature.The Lagrange pseudo-second order kinetic model,Langmuir isotherm and Freundlich equation were used to fit the data.The results showed that the modified HNTs were successfully obtained and the sorption capacity of the modified HNTs for methylene blue was high.The modified adsorbent had a rather rapid adsorption rate and reached adsorption equilibrium in 60 min.The maximal sorption capacity was 21.66 mg/g,which was higher than that of the unmodified halloysite nanotubes.The sorption process of methylene blue by the modified halloysite followed the pseudo second order kinetic model,and the adsorption process was mainly physical adsorption.The data for methylene blue system were fitter for the Langmuir isotherm model rather than Freundlich model.Thermodynamic parameters depicted the endothermic nature of adsorption and the process was spontaneous,and the sorption of methylene blue was increased with the increase of temperature.Furthermore,the as prepared adsorbent could be reused six times at least,which indicated that the modified HNTs have a potential usage in waste-water treatment.关键词：modified halloysite;silane coupling agent;methylene blue;adsorption
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- 995
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- 2
发布时间： - 摘要：A copper(Ⅱ) L-tryptophan complex was synthesized in aqueous solution and characterized by element analysis,differential scanning calorimetry and thermogravimetry,powder X-ray diffraction and Fourier transform infrared spectroscopy.The results showed that the compound had a good stability.A copper ion could combine with two L-tryptophan molecules through the nitrogen of the amine group and one oxyen of the carboxyl group.The low-frequency vibrational spectrum was measured by terahertz time-domain spectroscopy(THz-TDS) at room temperature.Density functional theory was employed to calculate the low-frequency vibrational properties.The result indicated that THz absorption spectrum mainly reflected the collective vibrational modes of the whole molecules including the distortional vibration of indole ring and the side chain.The studies are helpful to understand the interaction of copper ion with amino acid and the role of the copper ion in complex organisms.关键词：copper;L-tryptophan;metal complex;analysis method;terahertz time domain spectroscopy(THz-TDS)
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- 0
发布时间： - 摘要：A method was developed for the simultaneous determination and identification of ribavirin and amantadine residues in poultry meat by liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).The samples were purified with solid phase extraction column of PCX and QuEChERS method after extraction with 1% trichloroacetic acid-methanol(1∶1),then separated on a BEH HILIC column(2.1 mm×100 mm,1.7 μm) by gradient elution with mobile phases of 5 mmol/L ammonium acetate-methanol.An internal standard method was used for quantitative analysis.The electrospray was operated in positive mode and a multiple reaction monitoring(MRM) as survey scan.The results showed that the calibration curves were linear in the range of 0.50-200 μg/L for two analytes with correlation coefficients(r) more than 0.997.The limits of detection(LODs,S/N ≥ 3) for ribavirin and amantadine were 0.30 μg/kg and 0.15 μg/kg,respectively,and the limits of quantitation(LOQs,S/N ≥ 10) were 1.00 μg/kg and 0.50 μg/kg,respectively.On the basis of LOQs,the intra-day average recoveries for two analytes in poultry meat samples at three spiked levels(1,2,10 times LOQ) ranged from 92.5% to 104.7% with relative standard deviations(RSDs) of 3.4%-7.8%,while the inter-day average recoveries ranged from 93.3% to 106.0% with RSDs of 6.0%-10.7%.The method was sensitive,convenient and accurate,and could satisfy the demands for detection of ribavirin and amantadine residues in poulrty meat.关键词：dispersive solid phase extraction;ribavirin;amantadine;liquid chromatography-tandem mass spectrometry(HPLC-MS/MS);poultry meat
- 2046
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- 1074
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发布时间： - 摘要：A carbon fiber microelectrode modified with Nafion was fabricated by electrodeposition method on the basis of previous work.The electrochemical behaviour of norepinephrine(NE) and ascorbic acid(AA) at the prepared microelectrodes before and after modification were investigated using cyclic voltammetry(CV) and differential pulse votammetric(DPV) methods.Under the optimum conditions,the Nafion modified-electrode can completely shield the electrochemical response of AA,however,a sensitive response to NE was obtained on the modified electrode.Based on this,the modified electrode can be used to selectively detect NE without interference from high concentration AA.DPV response of NE showed a good linearity(r2=0.991 2) at the modified microelectrode with its concentration in the range of 1.0×10-6-1.0×10-4 mol/L,with a detection limit(S/N=3) of 8.6×10-7 mol/L.The proposed method was applied in the determination of NE in simulation sample with spiked recovery of 101.6%.The modified electrode exhibited almost the same electrochemical behavior after a month,indicating that the modified electrode is pretty stable and has a good reproducibility.The advantages of excellent sensitivity and selectivity made the modified electrode could be used to monitor NE in complex biological environment.关键词：Nafion;carbon fiber electrode;differential pulse voltammetry(DPV);cyclic voltammetry(CV);norepinephrine(NE);ascorbic acid(AA)
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- 1017
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发布时间： - 摘要：An efficient method was developed for the preparative separation of palmatine and jatrorrhizine from Tinospora capillipes Gagnep.by pH-zone-refined counter-current chromatography(CCC). The two phase solvent system of chloroform-methanol-water(4∶3∶2) was selected,in which hydrochloric acid(20 mmol/L) was added into the upper aqueous phase as the stationary phase,and triethylamine(10 mmol/L) was added to the lower orgnic phase as the mobile phase.The apparatus was rotated at a speed of 850 r/min,while the mobile phase was pumped into the column at 2.0 mL/min.From 2 g of crude extract,512 mg palmatine and 421 mg jatrorrhizine with purities of 95.1% and 95.3% were obtained.The chemical identification of the isolated compounds was carried out by electrospray ionization-mass spectrometry(ESI-MS),1H NMR and 13C NMR.The introduced method is a rapid and efficient approach for the preparative separation of palmatine and jatrorrhizine in tinospora capillipes gagnep.关键词：pH-zone-refined counter-current chromatography;high performance liquid chromatogranphy(HPLC);palmatine;jatrorrhizine;Tinospora Capillipes Gagnep.
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- 1053
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- 1
发布时间： - 摘要：An ultra performance liquid chromatography coupled with tandem mass spectrometric(UPLC-MS/MS) method was established for the simultaneous determination of oleanolic acid(OA) and ursolic acid(UA) in Chinese herbal medicine.The sample was detected by ultra performance liquid chromatography coupled with tandem mass spectrometry(UPLC-MS/MS).The separation of two compounds was achieved on a Waters Acquity UPLC BEH C18 column(50 mm×2.1 mm,1.7 μm) with a mobile phase of 5 mmol/L ammonium acetate in water(ammonium hydroxide adjust pH 9.24) and acetonitrile in gradient elution mode.The detection of the compounds was performed in negative ion mode.The result indicated that the concentration of OA and UA had good linear relationships with peak area in the concentration range of 0.5-50.0 ng/mL,and the correlation coefficients(r2) were 0.999 8 and 0.999 7,respectively.LODs(S/N=3) of the two compounds were 0.006 6 ng/mL and 0.012 8 ng/mL,respectively.LOQs(S/N=10) were 0.002 0 ng/mL and 0.003 8 ng/mL,respectively.The recoveries of OA and UA were 101.1% and 100.8%,with RSDs(n=9) of 1.8% and 0.04%,respectively.The method showed the advantages of simpleness,high accuracy and good reproducibility,and could be used for the detection of OA and UA content in the Chinese herb.关键词：Chinese herb;oleanolic acid;ursolic acid;ultra performance liquid chromatography coupled with tandem mass spectrometry(UPLC-MS/MS)
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发布时间： - 摘要：A novel method was proposed for the detection of loop mediated isothermal amplification(LAMP) products of Escherichia coli(E-coli)based on self-built capillary electrophoresis(CE)with lamp induced fluorescence system.Four primers were designed for the target DNA,and the sizes of the LAMP products of E-coli corresponding to the primers of F3,B3,FIP and BIP were 240 bp.The best result was achieved with the sieving polymer of 0.5% HEC(1 300 K),an electric field strength of 100 V/cm and an injection time of 1.0 s at the electric field strength of 100 V/cm.The migration time of DNA from 100 bp to 500 bp is linearly related with DNA size,and the correlation coefficient is 0.996.The LAMP products of E-coli were resolved under the same electrophoretic conditions.The sizes of the LAMP products were calculated based on the linear relationship,and the positive products was distinguished from the false-positive products.The results demonstrated that CE could not only rapidly separate the LAMP products of E-coli within 15 min,but also distinguish the positive from false-positive products.The proposed method was successfully applied in the separation of the LAMP products of AB0174 E-coli.Therefore,it is suitable for the rapid detection of LAMP products of DNA.关键词：loop-mediated isothermal amplification;capillary electrophoresis;false-positive product
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发布时间： - 摘要：Novel IL-porous carbons modified glassy carbon electrode(GCE) was prepared for the detection of tertiary butylhydroquinone(TBHQ).The results of electrochemical impedance spectroscopy showed that the electron transfer resistance(Rct) of the IL-porous carbon/GCE was much smaller than that of the bare GCE.For the detection of 8.00 μg/mL TBHQ,the oxidation peak current at the IL-porous carbon/GCE was 41.93 μA,which was about 5.5 times of that at the bare GCE.This indicated that IL-porous carbon could increase the conductivity of the electrode,improve the electron transfer and the detection sensitivity.Therefore,the presence of IL-porous carbon on the electrode surface could enhance the detection sensitivity.Depending on the amperometrici-time curve,the calibration curve for TBHQ determination demonstrated a linear response in the range of 1.00-120.00 μg/mL with a detection a limit of 0.16 μg/mL．关键词：IL-porous carbon;modified electrode;tertiary butylhydroquinone(TBHQ);oil
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发布时间： - 摘要：A simple magnetic stirring process to synthesize poly(diaminoanthraquinone)/ multi walled carbon nanotubes(PDAAQ/MWCNTs)composite using 1,4-diaminoanthraquinone(DAAQ)and multi-walled carbon nanotubes(MWCNTs)via π-π stacking was reported.The as prepared composite was investigated by Fourier transform infrared spectroscopy(FTIR),transmission electron microscopy(TEM),cyclic voltammetry(CV)and galvanostatic charge discharge(GCD).The results showed that a 3-4 nm thickness of PDAAQ was well coated on the outer surface of the MWCNT,which clearly indicated the formation of a multilayer of DAAQ molecules on the nanotube surface.This unique structure of PDAAQ/MWCNTs composite greatly increases the surface area of composite and the utilization of PDAAQ.Thus,the homogeneous PDAAQ/MWCNTs composite exhibits a high pseudocapacitance characteristic.关键词：multi-walled carbon nanotubes(MWCNTs);1,4-diaminoanthraquinon(DAAQ);PDAAQ/MWCNTs composite;supercapacitor
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发布时间： - 摘要：Molecularly imprinted electrochemiluminescence sensors combine the specific recognition ability and predetermined selectivity properties of molecularly imprinted polymer with the high sensitivity of electrochemiluminescence technology.In addition,these sensors exhibited a high maneuverability for luminescence signal from the reactions with good reproducibility,long-term stability and easy operation,which have received a great deal of attention in applications of pharmaceutical analysis,heavy metal ion detection,immune biosensors,gene biosensos,enzymatic biosensors,toxic pesticide residue detection and food safety monitoring.The preparation mechanism and construction thinking of the sensors are summaried in this review.Moreover,the applications on food safety and drugs detection of molecular imprinted polymer electrochemiluminescence sensors are highlighted,and the development trend of molecular imprinted polymer electrochemiluminescence sensors is revealed.关键词：molecular imprinting;electrochemiluminescence;food safety and drug analysis;review
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