最新刊期
卷 35 ， 期 8 ， 2016
- 摘要：A molecularly imprinted nanoshell was prepared successfully by using dibenzyl phthalate (DBzP) as template and silica microspheres as supporter based on the combination of the molecular imprinting technique,sol-gel and seed-mediated growth synthesis.The imprinted microspheres were characterized by FT-IR and SEM.Meanwhile,a series of adsorption experiments were performed to investigate the adsorption characterization of the imprinted particles.The imprinted particles reached an adsorption equilibrium within 30 min,and the adsorption behavior was in accordance with the pseudo second order model.The maximum adsorption was up to 47.35 mg/g at ambient temperature.The adsorption isotherms of DBzP onto the imprinted particles were well described by Langmuir isotherm model,Freundlich isotherm model and Scatchard model at different temperature,respectively.The results indicated that the Langmuir isotherm model was more suitable to describe the adsorption process than Freundlich model.The Scatchard analysis suggested that the imprinted particles had only one binding site with homogeneous distribution trait.The imprinted particles also showed an more excellent selectivity to DBzP than other four structural analogues.The rebinding capacities of the imprinted particles remained 83% after 10 cycles of adsorption-desorption under the relatively mild regeneration conditions.Simultaneously,the method for the determination of DBzP in plastic package samples via the imprinted particles coupled with UPLC was developed，it was also successfully applied in the analysis of DBzP in two spiked plastic package samples with average recoveries of 88.8%-93.1% and the relative standard deviation lower than 6%.Thus,the imprinted polymer is one of outstanding candidate materials for extraction of DBzP in food or their packaging materials.关键词：seed-mediated growth synthesis;silica microparticle;imprinting nanoshell;dibenzyl phthalate;food packaging materials
- 2397
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- 1209
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- 1
发布时间： - 摘要：A method was developed for the determination and conformation of 21 illegal chemical drugs in antihypertension traditional Chinese medicines and health care foods by HPLC-DAD and LC-MS/MS with sub-3 μm particle column.The samples were extracted with methanol-acetonitrile(5∶5,by volume),then separated on an Agilent Poroshell 120 phenyl-Hexyl(100 mm×4.6 mm,2.7 μm) by gradient elution with methanol-acetonitrile(2∶1,by volume)- formic acid water solution(pH 2.5±0.1) as mobile phase,detected with DAD in wavelength range of 200-400 nm.Quantification analysis were performed by the external standard method.The positive samples were further identified and verified by LC-MS/MS.The results indicated that 21 analytes were separated completely in 17 min.The detection limits of 21 target compounds ranged from 0.03 mg/g to 0.50 mg/g.The average recoveries at three spiked levels ranged from 82.0% to 109.0%.The method was applied in the analysis of 107 batches of samples from online shopping,among which 45 batches were added with the chemicals with a positive rate of 42.1%.The method was accurate,rapid and sensitive,and was suitable for the determination of illegally added chemical drugs in traditional Chinese medicine and healthy food of antihypertension.关键词：traditional Chinese medicine and healthy food of antihypertension;illegal;HPLC;LC-MS/MS
- 1815
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- 1063
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- 9
发布时间： - 摘要：An ultrahigh performance liquid chromatography-tandem mass spectrometric(UPLC-MS/MS) method was developed for the simultaneous determination of 2-methylimidazole(2-MEI) and 4-methylimidazole(4-MEI) in various foods.Most of foods could be injected directly after ultrasonic extraction.Solid phase extraction was needed for extremely complex sample matrix(such as sauce,coffee and tea),and the target analytes were quantified by isotope internal standard.Under the optimized conditions,the limits of detection for 2-MEI and 4-MEI were up to 0.5 ng/g and 1.4 ng/g,respectively,the recoveries of the method ranged from 82.6%to 98.1%for 2-MEI and 89.5%to 108.1%for 4-MEI.The intraday RSDs of 2-MEI and 4-MEI were 1.3%-4.5%and 1.0%-5.0%,while their inter-day RSDs were 2.0%-5.4%and 1.9%-6.5%,respectively.The results indicated that the method was suitable for simultaneous determination of 2-MEI and 4-MEI in food matrices.This method was applied in more than 90 kinds of foods,in which 2-MEI was only observed in several samples and the contents were relatively low,whereas 4-MEI was detected in most of the tested foods,including dark soy sauce(3 224.20-18 795.93 ng/g)，coffee(0-5 554.35 ng/g)，cookie(63.48-584.78 ng/g)，biscuit(containing caramel,373.12-1 899.60 ng/g)，cola(44.13-342.77 ng/g) and barley tea(3 131.05-3 335.60 ng/g).This study also reported the contents of 4-MEI in different varieties of tea(16-761.89 ng/g) for the first time.关键词：ultrahigh performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS);2-methylimidazole(2-MEI);4-methylimidazole(4-MEI);food
- 1958
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- 1077
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- 5
发布时间： - 摘要：By taking CdSe/ZnS quantum dots as a fluorescence probe,a method for the rapid detection of fluorescence of dopamine was developed based on fluorescence quenching effect of dopamine to CdSe/ZnS quantum dots.Under the optimal experimental conditions(pH 7.4,reaction time:20 min),the fluorescence quenching strength ratio of CdSe/ZnS quantum dots had a good linear relationship(r=0.996) with concentration of dopamine in the range of 0.01-0.7 μmol/L.The detection limit was 1.6×10-4 μmol/L,and the relative standard deviation of this method was 1.2%.Compared with some approaches reported in current literatures,this method has a lower detection limit and higher sensitivity.The method could be applied in the rapid detection of dopamine injection and dopamine in human’s urine sample.关键词：CdSe/ZnS quantum dots;dopamine;fluorescence;detection
- 1844
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- 906
- |
- 11
发布时间： - 摘要：Migration investigations were carried out on typical antioxidant and plasticizer 3-tert-butyl-4-hydroxyanisole(BHA),2,6-di-tert-butyl-4-methylphenol(BHT) and dicyclohexyl phthalate(DCP) with the modified polyphenylene oxide(also referred to as Tenax TA) as the dry food simulant.Two types of paperboard samples,kraftpaper and lvory board,were selected to take part in a series of designed migration tests under different temperatures with different times,in order to obtain the migration behaviors of three migrants.The migration results implied that for almost all of organic compounds,their migrations underwent two steps including firstly adsorption of the released compounds from paperboard,secondly desorption of migrant from Tenax TA.During the first stage,the big pore size in paperboard microstructures and weak interaction between migrants and paper fiber could lead to high migration rate of the migrants,eventually resulted in the high adsorption efficiency of the simulant.However,when the adsorption reached an equilibrium between migrants and simulant,prolonging of the migration time would trigger desorption of migrant from the simulants,and resulted in the reduction of migration efficiency.A screening test for forty five kinds of paper packaging materials was implemented,and the results demonstrated that BHA and DCP were presented in two types of the paper packaging materials,and the migration levels were 0.027 μg/dm2 and 0.81 μg/dm2,respectively,smaller than the specific migration limits regulated in the European Commission Directive.关键词：paper;food contact material;antioxidant;plasticizer;dry food simulant;Tenax TA;migration;ultra high performance liquid chromatography
- 1888
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- 3
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- 1
发布时间： - 摘要：Indole-3-acetic acid（IAA） imprinted polymer microparticles were synthesized using IAA as template,acrylamide（AA） as functional monomer and ethylene glycol dimethacrylate as crosslinker in acetonitrile porogen via precipitation polymerization.Effects of amounts of IAA and acetonitrile utilized in the polymerization reaction on the binding performances of IAA imprinted polymers were evaluated by high-performance liquid chromatography（HPLC）.The results showed that the IAA imprinted polymer P7 with the highest affinity（k=4.24） and imprinting factor（IF=14.1） for IAA was obtained when the molar ratio of IAA to AA 1∶1 was adopted with 2 mmol of IAA in 37.5 mL of acetonitrile porogen.Furthermore,P7 was chosen as the packing material to make the molecularly imprinted solid phase extraction（MISPE） column,and the MISPE method was developed for the purification of IAA .Under the optimized extraction conditions,the mungbean sprout samples spiked with IAA were extracted,and the recoveries of IAA ranged from 90.6%to 92.6%.The results demonstrated that the IAA-imprinted polymer particulates prepared using AA as the functional monomer by precipitation polymerization could be used as the adsorbent of solid phase extraction column for the selective separation and purification of IAA in real samples.A new route was proposed in this paper to synthesize an imprinted polymer with high affinity and high selectivity by means of increasing amount of template appropriately in the pre-polymerization mixture.关键词：indole-3-acetic acid（IAA）;precipitation polymerization;molecularly imprinted polymer;solid phase extraction;high performance liquid chromatography（HPLC）;mungbean sprout
- 2315
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- 1064
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- 1
发布时间： - 摘要：A method for the simultaneous determination of 16 polycyclic aromatic hydrocarbons(PAHs) in tobacco by four-channel chromatograph purification coupled with gas chromatography-mass spectrometry(GC-MS) was developed.The tobacco samples were extracted by the method of soxhlet extraction with dichloromethane,and the extract was cleaned with four-channel purification chromatograph.The eluent were determined by GC-MS in SIM mode,and quantitated by a method of external standard.The procedure of separation and purification for fresh tobacco extraction was optimized.The results indicated the calibration curves of 16 PAHs had good linear relationships in the range of 10-1 000 μg/kg(r＞0.99).The detection of limits(LODs) and method detection limits(MDLs) were 0.35-1.75 μg/kg and 1.01-2.87 μg/kg,respectively.The recoveries at three spiked concentration levels were in the range of 81.0%-107.8%with relative standard deviations(RSD,n=6) of 2.7%-8.0%.The method is suitable for the determination of PAHs in tobacco or other crops with easy operation,rapidness,high repeatability and strong practicability.关键词：four-channel purification chromatograph;gas chromatography-mass spectrometry(GC-MS);polycyclic aromatic hydrocarbons(PAHs);purification;tobacco
- 1881
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- 923
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- 4
发布时间： - 摘要：A method was developed for the simultaneous determination of 18 phenols pollutants in water samples by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS) combined with direct injection.The water samples were filtered through 0.22 μm of polytetrafluoroethylene(PTFE) microfiltration membrane.With methanol-0.01 mol/L ammonium formate/ formic acid aqueous solution (pH 4.0) as mobile phase，the separation was performed on a Thermo Hypersil ODS column(100 mm×2.1 mm，5.0 μm) by gradient elution.The flow rate was 0.2 mL/min.The column temperature was 30 ℃.Samples were detected in multiple reaction monitoring (MRM) mode with negative electric spray ionization.The phenols pollutants were quantified by the external standard method.The calibration curves of the phenols pollutants showed good linearities in a certin concentration range with correlation coefficients(r2) not less than 0.999 1，the detection limits of phenols pollutants ranged from 0.02 μg/L to 0.51 μg/L.The relative standard deviations(RSD，n=6) of 18 phenols pollutants were in the range of 0.6%-4.3%.The spiked recoveries of 18 phenols pollutants at low,medium and high levels ranged from 84.5% to 112%.The method was sensitive，rapid and little interference.It is suitable for the simultaneous determination of 18 phenols pollutants in relatively clean water samples，such as groundwater and surface water.关键词：high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS);phenols pollutants;surface water;groundwater;direct injection
- 1823
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- 1076
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- 5
发布时间： - 摘要：Graphene oxide(GO) has received great interest for its unique properties and potential applications in separation.Here,(GO)@SiO2 composites-based stationary phase for high performance liquid chromatography(HPLC) were fabricated by covalently bonding GO onto aminosilica microspheres using N,N-dicyclohexylcarbodiimide as coupling agent.The reaction was achieved via coupling the amino groups of aminosilica and the carboxyl groups of GO.The prepared GO@SiO2 was characterized by scanning electron microscopy and Raman spectroscopy.GO@SiO2 composites were developed as stationary phase,and the chromatographic properties of bare SiO2 and GO@SiO2 were investigated by a series of polar compounds including melamine,cyanuric acid,clenbuterol,4-aminoantipyrine and 4-methylaminoantipyrine.Under the same conditions,GO@SiO2 column obtained a better separation for polar analytes in hydrophilic mode and the column was used as an analytical column for the determination of melamine in egg and milk samples.The proposed method was linear over the range of 0.2-50.0 μg/mL with a correlation coefficient(r) of 0.999 9.The limit of quantitation for melamine was 0.87 mg/kg.The recoveries of melamine at three spiked levels of 1,2,10 mg/kg ranged from 84.7% to 93.9% with relative standard deviations (RSDs) of 4.1%-6.3%.关键词：graphene oxide(GO);stationary phase;melamine;milk;egg;high performance liquid chomatography(HPLC)
- 1810
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- 960
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- 1
发布时间： - 摘要：An analytical method for the simultaneous determination of three restricted flavor additives(3-thujanone,camphor and safrole) in tobacco products by solid-phase extraction with gas chromatography-tandem mass spectrometry(GC-MS/MS)was developed and evaluated.The extraction conditions and MS conditions were optimized.Under the optimal conditions,three flavor additives had good linearities in the range of 10.0-500.0 μg/L,with correlation coefficients(r2) not less than 0.998 6.The limits of detection(LODs) and limits of quantitation(LOQs) for these additives were in the ranges of 2.3-5.8 μg/kg and 7.7-19.3 μg/kg,respectively.The average recoveries of three analysts were in the range of 74.9%-90.9% at three spiked levels of LOQ,1.5 LOQ and 2 LOQ,with relative standard deviations(RSDs) not more than 2.6%.The method is accurate,reliable and sensitive,and could satisfy the requirements for detection of three restricted flavor additives in domestic.关键词：solid phase extraction(SPE);gas chromatography-tandem mass spectrometry(GC-MS/MS);restricted flavor additives;cigarettes
- 1903
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- 1025
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- 3
发布时间： - 摘要：An electrochemical sensor for the determination of ronidazole(RNZ) was developed based on a magnetic glassy carbon electrode modified with Al(Ⅲ) doped core-shell magnetic surface molecularly imprinted polymer(MMIP),which was prepared via the sol-gel method using RNZ as template,3-aminopropyltriethoxysilane as functional monomer,orthosilicate as cross-linker,and Al3+ as dopant to generate Lewis acid sites in the silica matrix for the metal coordinate interactions with the template RNZ.The component,morphology of MMIP and the performance of the as prepared sensor were characterized by transmission electron microscopy,Fourier transform infrared spectroscopy,powder X-ray diffraction and the electrochemical methods.Various factors affecting the response behavior of the sensor were studied and optimized.Because of the aluminum doping,the imprinted sensor exhibits the best recognition ability and affinity for RNZ in comparison with the aluminum free MMIP and the non-imprinted one.Under the optimal experimental conditions,the peak currents by differential pulse stripping voltammetry were found to vary linearly with RNZ concentrations in the range of 0.05-50.0 μmol/L with a detection limit of 0.015 μmol/L.This sensor was successfully employed to detect RNZ in milk powder and egg samples with recoveries of 88.6%-97.0%and relative standard deviations of 2.9%-4.6%.关键词：ronidazole(RNZ);magnetic surface molecularly imprinted polymer;differential pulse stripping voltammetry;aluminum doping
- 2406
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- 1110
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- 0
发布时间： - 摘要：Selecting 2-chlorovinylarsonic acid(CVAOA) as the biomarker,a determination method of ultra-trace CVAOA in human urine specific to lewisite exposure was developed.The conditions for derivatization were optimized by orthogonal experiments,and the results were as follows:thiolation by a 1∶1 000 mole ratio of CVAOA to 3,4-dimercaptotoluene(DMT) for 5 min at room temperature.Enrichment and purification of the derivative product(CVAOA-DMT) based on the optimum headspace-solid phase microextraction(HS-SPME) conditions,and then analysis of the derivative by gas chromatography-mass spectrometry in selective ion monitoring(GC-MS-SIM).The linear calibration range was from 50.0 pg/mL to 500 ng/mL(r2=0998 5),and the relative standard deviations(RSDs) were less than 10%.The limit of detection was 7.6 pg/mL and the limit of quantitation was 23 pg/mL.The recoveries of lewisite exposed urine samples at the low,middle and high concentration levels ranged from 97.6% to 105% with the RSDs of 4.4%-7.1%.The method exhibited a satisfactory universality with its high sensitivity,precision and accuracy,and could be applied in different laboratories.关键词：2-chlorovinylarsonic acid;lewisite;urine;ultra trace;solid phase microextraction(SPME);gas chromatography-mass spectrometry(GC-MS)
- 1832
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- 906
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- 3
发布时间： - 摘要：The volatile flavor compounds in 22 tobacco chewing gums were identified by static headspace/GC-MS with mass spectrum library.The analytical sensitivity was increased significantly by optimizing instrumental conditions of the headspace unit and GC-MS.Sixty-five volatile flavor compounds were identified on the basis of normalized peak areas（＞0.1%） and matching degree（＞85%）.It was found that the main volatile flavor compounds in tobacco chewing gums were esters（18 compounds）,alkenes（16 compounds）,alcohols（9 compounds）,aldehydes（8 compounds）,ketones（7 compounds）,phenols（1 compound）,acids（1 compound）,furans（2 compounds）,alkanes（2 compounds） and sulfoether （1 compound).The results indicated that satisfactory identification and classification were realized among the experimental samples,and the sample taste would affect the brand recognition.It could be applied in the future development of tobacco chewing gum products by using theoretical and technical outcomes of the established method.关键词：HS/GC-MS;tobacco chewing gum;volatile flavor compounds
- 1813
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- 996
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- 2
发布时间： - 摘要：A capillary GC-MS method was established for the determination of nine kinds of new cooling agents in mint flavor foods and daily necessities.The samples were ultrasonically extracted with ethanol,and separated on a DB-1701MS column(30 m×0.25 mm×0.25 μm),then the extract was detected by MS under SIM mode.Those new cooling agents have good resolution and linear relationships within the concentration range of 0.25-250 μg/mL under the optimum conditions.The detection limits for most of cooling agents were less than 0.1 μg/g,except menthoxypropanediol(0.26 μg/g).The spiked recoveries were in the range of 82.8%-103.5% with relative standard deviations(RSDs,n=6) not more than 3.7%.The method has the advantages of short peak retention,high-sensitivity,accurancy,reliability,good reproducibility and selectivity,and could provide some scientific data for the quality control of mint flavor food and the analysis of cooling agent composition in unknown sample.关键词：gas chromatography-mass spectrometry(GC-MS);cooling agent;daily necessities;food
- 1926
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- 1090
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- 0
发布时间： - 摘要：Double pulse laser-induced breakdown spectroscopy(DP-LIBS) was used to detect lead(Pb) content in soybean oil.For nine prepared soybean oil samples in the experiment,cylindrical paulownia wood with a certain size was used to enrich Pb in samples,and LIBS spectrum was collected by an Ava-Spec two-channel high precision spectrometer.According to LIBS spectrum of the sample and the National Institute of Standards and Technology(NIST) atomic spectrum database,the characteristic spectral line intensties of Ca Ⅱ 393.284 nm,Ca Ⅱ 396.752 nm,N Ⅱ 399.399 nm and Pb Ⅰ 405.685 nm were selected as independent variables,and multivariate linear regression was used to develop a quantitative analysis model for Pb content.The methods of variance analysis and t-test were used to verify the feasibility of analysis model.The results indicated that the average relative error of Pb was about 16%,and the fitting degree R2 was 0.981 8 in the direct calibration method.While in the multiple linear regression model,the average relative error of Pb was 7.25%,and the fitting degree R2 was 0.997 1,the relative errors of three validated samples were within a reasonable range.It is showed that the multivariate calibration analysis model could make full use of the effective information in the spectrum and reduce the influence of matrix effect,thereby improving the accuracy of LIBS analysis.关键词：double pulse LIBS;multivariate calibration;quantitative analysis;soybean oil;lead
- 1852
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- 899
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- 1
发布时间： - 摘要：A method of QuEChERS sample preparation was optimized and the QuEChERS-GC method for simultaneous analysis of 31 organophosphorous pesticide residues in fruits were established in this study.The samples were extracted with acetonitrile，and salted out with sodium chloride.The extracts were cleaned up by dispersive solid phase extraction using C18 and magnesium sulfate as sorbents，then determined by GC/FPD with matrix-matched standards procedure.The external standard method was used for quantitative analysis.The results showed that the correlation coefficients of linear equations(r2) were in the range of 0.990 3-0.999 9.The recoveries of 31 organophosphorus pesticides in various spiked levels ranged from 81.7% to 120.7%，with RSDs of 0.4%-14.7%.The limits of detection(LOD) were in the range of 0.4-6 μg?kg-1.The method showed the advantages of simplicity，rapidness，sensitivity and low consumption.It could meet the demands for the simultaneous determination of multi-residue organophosphorous pesticides in fruits.关键词：QuEChERS;gas chromatography(GC);fruits;organophosphorous pesticide
- 1907
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- 1069
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- 10
发布时间： - 摘要：An unknown compound in petroleum aromatics was analyzed by Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS) coupled with atmospheric pressure photoionization(APPI)，electrospray ionization(ESI) and direct analysis in real time(DART) ionization.It was determined as tris(2，4-di-tert-butylphenyl)phosphate(TDTBPP) by the accurate mass of FT-ICR MS and collision activated dissociation(CAD).The characteristic spectra of TDTBPP in multiple ionization sources were demonstrated.The result indicated that the main mass peak in APPI was ［M+H］+，and M.+ was also present.The main mass peak in ESI was ［M+Na］+(without formic acid) or ［M+NH4］+(with formic acid)，and the main mass peak in DART was ［M+NH4］+.APPI FT-ICR MS could be used to determine the polycyclic aromatic hydrocarbons(PAHs) with relatively higher molecular weight which could not be determined by gas chromatography-mass spectrometry.关键词：tris(2,4-di-tert-butylphenyl)phosphate;atmospheric pressure photoionization(APPI);electrospray ionization(ESI);direct analysis in real time(DART);Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS);aromatics
- 1981
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- 1110
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- 1
发布时间： - 摘要：A new research for authentic grape juice adulteration identification using elemental analysis-isotope ratio mass spectrometry(EA-IRMS) was developed.The carbon isotope ratio values(δ13C values) for 152 grape samples from different production regions were collected to primarily construct the isotopic database of authentic grape juices.The results indicated that the δ13C values of sugar and organic acid were in the ranges of -26.92‰-24.16‰ and-27.56‰-24.99‰，respectively.Based on the above δ13C values collected,the δ13C value limit for the authentic grape juice was proposed:the δ13C difference between organic acid and sugar Δδ13CO-S should be from-1.63‰ to 0.72‰.According to the above criteria,among 85 commercial samples,31 samples were confirmed adulterated with C-4 plant sugar or organic acid.According to the syrup addition test,EA-IEMS method could identify over 8%C-4 plant sugar adulteration.The newly developed method represented a significant potential application in the quality assurance of grape juice.关键词：elemental analyzsis;isotope ratio mass spectrometry;grape juice adulteration;C-4 plant sugar
- 1844
- |
- 1054
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- 6
发布时间： - 摘要：A microwave assisted micro-solid phase extraction（MAE-μ-SPE） combined with gas chromatography-mass spectrometric（GC-MS） method was developed for the determination of 19 polychlorinated biphenyls（PCBs） in environmental sludge sample.Target PCBs compounds were extracted from the sludge sample into extraction solvent enhanced by microwave field,followed by adsorption with adsorbent in the micro-solid phase extraction device.The copper（Ⅱ） isonicotinate（Cu（4-C5H4N-COO）2（H2O）4） coordination polymer was prepared and used as the adsorbent.Variables affecting extraction procedures were systematically investigated,and the experimental conditions of MAE-μ-SPE were optimized.The major optimized parameters were as follows:extraction temperature:60 ℃,extraction time:25 min,desorption time:25 min,desorption solvent:150 μL ethyl acetate.Then,a GC-MS method for determination of 19 PCBs was studied.The detection limits（S/N=3） of the method ranged from 0.2 ng/g to 2.5 ng/g,and the relative standard deviations（RSD） were lower than 14%.The mean recoveries were in the range of 81.4%-102.1%.The experimental results demonstrated that the developed MAE-μ-SPE/GC-MS method combining extraction,cleanup,and concentration in one step,was suitable for analysis of trace PCBs in complex samples.关键词：microwave-assisted micro-solid phase extraction;gas chromatography-mass spectrometry（GC-MS）;polychlorinated biphenyls(PCBs);environmental analysis;sludge
- 1879
- |
- 991
- |
- 6
发布时间： - 摘要：Sterigmatocystin,a mycotoxin produced by fungi and widely distributed in cereal food,has a potential toxic effect to human and animals with risk on food safety.In this study,a rapid,simple and accurate high performance liquid chromatography-tandem mass spectrometric(HPLC-MS/MS) method was established for the analysis of sterigmatocystin in rice and millet by optimizing extraction solvent and its volume,ultrasonic time and adsorbent.The samples were extracted with acetonitrile,and cleaned up with PSA,then detected after the supernatant was filtered through nylon filter.The detection was performed in the electrospray ion(ESI) positive mode and multiple reaction monitoring(MRM) mode.The sterigmatocystin showed good linear relationships in the range of 0.1-100.0 μg/L with correlation coefficients not less than 0.999 0．The limit of detection(LOD) and the limit of quantitation(LOQ)for sterigmatocystin in rice were 0.03 μg/kg and 0.1 μg/kg,respectirely,the recoveries ranged from 88.3% to 91.5% with relative standard deviations(RSDs) of 2.3%-6.0%.The LOD and LOQ for sterigmatocystin in millet were 0.1 μg/kg and 0.3 μg/kg,respectively,and the recoveries were 92.7%-103.8% with RSDs of 2.2%-6.9%.The proposed method could meet the requirement for trace analysis.The method was applied in the the detection of the collected rice and millet samples,and no sterigmatocystin was detected.关键词：sterigmatocystin;rice;millet;high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)
- 1848
- |
- 1061
- |
- 0
发布时间： - 摘要：A bodipy-based fluorescence probe for thiols was developed with high sensitivity and excellent selectivity at a physiological pH(7.4) value.Its structure was characterized by nuclear magnetic resonance(NMR) and high resolution mass spectrometry(HRMS).This probe was designed based on the mechanism that thiols induced the Michael addition reaction to block photo-induced electron transfer process(PET) in this probe.The addition of thiols(0-1 000 μmol/L) to the solution of probe resulted in a remarkable fluorescence enhancement(150-fold) in the green spectra region.Meanwhile，probe was able to detect relatively low concentrations of thiols and the fluorescence detection limit for common amino acids containing thiols，Cys was determined to be 4.5×10-7 mol/L.Additionally，similar results were obtained affording 1.2×10-7 mol/L and 2.1×10-7 mol/L detection limits for GSH and Hcy，respectively.The probe exhibited high selectivity and sensitivity towards thiols over other amino acids.Most importantly，the probe has been successfully utilized for thiols imaging in living cells，which makes it a good candidate for application in biological systems.关键词：synthesis;application;fluorescence probe;determination;biothiols
- 2006
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- 972
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- 4
发布时间： - 摘要：A novel plate-type glass-supported gold-film electrode was fabricated by means of ion sputtering.Cr（Ⅵ） could be electrochemically reduced at the proposed electrode.After optimization of parameters,including sputtering time,current and supporting electrolyte,Cr（Ⅵ） could be determined using either linear sweep voltammetry with a detection limit（S/N=3） of 6.5 μg/L or amperometry with a detection limit of 2.0 μg/L.The batch-by-batch reproducibility（n=10） was 9.2%and the electrode-by-electrode reproducibility（n=10） in same batch ranged from 9.2%to 25.8%.The proposed electrode is easy-to-fabricate and economical,and is available for mass production.The method was applied in the determination of Cr（Ⅵ） in real samples including plastic and lake water,and the results were consistent with those obtained by the HPLC-ICP-MS method.关键词：ion sputtering;gold-film electrode;Cr（Ⅵ）;linear sweep voltammetry;amperometry
- 1893
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- 1001
- |
- 1
发布时间： - 摘要：A simple and universal aptamer-based label-free approach for highly selective and sensitive fluorescence detection of thrombin was designed.The method is based on the specific recognition ability of label-free aptamer towards their targets,and PicoGreen dye was used to transduce the fluorescent signal of the double strand DNA duplex.As an asymmetric cyanine dye,PicoGreen reagent does not produce any fluorescence signal when it extsts alone.However,upon binding to dsDNA,it shows a significant fluorescence signal whereas no significant fluorescence change could be observed when it binds to ssDNA.Based on this property,it was used in the detection of thrombin.The results showed that a dynamic range of 1.0×10-14-1.0×10-7 mol/L(r2=0.99) was obtained with a detection limit as low as 1.0×10-14 mol/L.In order to determine the specificity of this method,the sensing system against two interfering substances such as bovine serum albumin(BSA) and cytochrome C(Cyt C) was tested.It is found that the interfering substances(each at 1.0×10-8 mol/L) could not effect on the detection of thrombin,which indicated the high selectivity of the sensing method toward thrombin.The present method was successfully applied in the determination of thrombin in real human serum with average recoveries of 97%-102%.The experiments results demonstrated that the proposed method was simple,specific and sensitive,and it was hopeful to apply in the field of medical clinical diagnosis.关键词：aptamer;biosensor;fluorescence;thrombin
- 1922
- |
- 943
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- 2
发布时间： - 摘要：SiF4 was qualitatively and quantitatively analyzed by Fourier transferred infrared spectroscopy.The linear range for the method was 10-500 μL/L,and the detection limit was 1 μL/L.The method was applied in the potential fault diagnosis of SF6 gas insulated switch,and the effectiveness of the SiF4 in the diagnosis of the internal conditions in the equipment was verified.关键词：high voltage insulation equipment;Fourier infrared spectroscopic analysis;SF6 decomposition product;SiF4 detectionSF6
- 1880
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- 945
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发布时间： - 摘要：As a new type of analysis and detection technique,surface-enhanced Raman spectroscopy（SERS） has attracted more and more attention due to its unique properties of rapid detection,high sensitivity,non-destructive and the in-situ detection ability.Therefore,SERS has a great development potential and an application prospect as a spectral analysis technique.Recyclable SERS-active substrates with high sensitivity,highly enhanced intensity and good repeatability and stability have a great influence on the intensity of SERS signals.A variety of different functional nanomaterials can be composited through layer-by-layer,surface modification method and sonochemistry coating to form core-shell nanoparticles as novel SERS-active substrates.They can not only enhance the reproducibility of SERS signal,but also maintain the stability of the core-shell nanoparticles in analysis.The conventional SERS substrates mainly include metal colloids,metal island films,chemical etched metal films,etc.However,those SERS substrates have the disadvantages of poor reproducibility and stability.In contrast to those traditional monocomponent SERS substrates,more stable SERS signals could be achieved by using core-shell nanoparticles with functions of enrichment and separation,catalysis and specific molecular recognition,which promote the further research of SERS theory and the application of SERS technology.In this review,recent advances of SERS-active substrates based on modified noble metal,magnetic nanocomposites,semiconductor,complex organic core-shell nanoparticles were reviewed.关键词：surface-enhanced Raman spectroscopy;novel SERS active substrate;core-shell nanoparticles;hybrid nanomaterials;review
- 1895
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- 1029
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发布时间： - 摘要：Nitroaromatics,as a kind of organic compounds,are a class of important chemical raw materials,which are also highly toxic pollutants with stable structures and difficult degradation.The main detection techniques for nitromatics were spectrophotometry,electrochemistry,high pressure liquid chromatography(HPLC),gas chromatography-electron capture detection(GC-ECD) and gas chromatography-mass spectrometry(GC-MS).Among them,GC-ECD and GC-MS were more widely used because of their accuracy,sensitivity and wide application.In this paper,the research progress on aromatic compounds in different types of water matrixs in the aspects of sampling,pretreatment and determination methods were briefly reviewed.The new detection techniques for aromatic compounds were also prospected.关键词：water matrix;nitroaromatic compounds;organic pollutants;analysis methods;research progress;review
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