最新刊期
卷 36 ， 期 11 ， 2017
- 摘要：A high throughput method based on gas chromatography-triple quadrupole mass spectrometry(GC-MS/MS) was established for the determination of 25 kinds of organophosphate esters(OPEs) and phthalate esters(PAEs) compounds in baked foods and plastic packing materials.For baked foods,the samples were ultrasonically extracted with acetonitrile:acetone(8∶2，by volume),and then purified by QuEChERS with 50mg C18 and 50mg PSA.For plastic packaging materials,GC-MS/MS analysis was performed directly after dichloromethane-methanol extraction.All the samples were separated with a DB-5ms chromatographic column,and detected in selected reaction monitoring(SRM) mode. The correlation coefficients for 25 compounds were not less than 0.9975,and the method detection limits were in the range of 10-500μg/kg. The average recoveries(n=6) ranged from 80.2%-119.6% with the RSDs of 1.5%-9.4%.The developed method, with the advantages of easy operation, satisfactory purification effect and favorable matrix effect elimination capacity, was suitable for the determination of OPEs and PAEs in different kinds of baked foods and plastic packing materials.关键词：organophosphate esters;phthalate esters;baked foods;plastic packing materials;gas chromatography-triple quadrupole mass spectrometry(GC-MS/MS)
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发布时间： - 摘要：To address the fast detection need towards poisoned patients in clinic,a sensitive,accurate liquid chromatographic-tandem mass spectrometric method was developed here for the qualitative and quantitative determinations of twelve anticoagulant rodenticides in dried blood spots.For the thoroughly punched dried blood spots,conditions influencing the extraction efficiency,including the kind of filter paper card,the water-soaking step and the kind of extraction solvent were investigated.A C18 column was employed as separation phase while ammonium acetate in water(5mmol/L)-ammonium acetate in methanol(5mmol/L) was used as mobile phase by gradient elution.Then the sample was detected using negative electrospray ionization under multiple reaction monitoring mode.The results showed that,with the 903 type filter card as supporting matrix and a water-soaking step,followed by an extraction with methanol solvent containing internal standard for 5min,the extraction efficiencies of the twelve rodenticides ranged from 66% to 115% with their intra-day relative standard deviations less than 15%.Good method validation results were obtained for all the anticoagulant rodenticides.The linearity for pindone was from 20 to 500 ng/mL with a correlation coefficient(r2) of 0.9987,and that for the other eleven analytes were from 5 to 500ng/mL with their r2 of 0.9988-0.9996. The recoveries for all the analytes ranged from 61% to 105%,with the matrix effects of 71%-193% and the intra-day relative standard deviations less than 15%.The established method was accurate,sensitive,rapid and convenient,and was successfully applied in the rapid detection of rodenticides in three clinic blood samples. It provides a new approach for clinical diagnosis and forensic toxicant analysis on anticoagulant rodenticide intoxication accidents.关键词：dried blood spot;anticoagulant rodenticide;liquid chromatography-tandem mass spectrometry;fast detection on poisoned clinical samples
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发布时间： -
Study on Effects of Temperature on Metabolism of Aspergillus Flavus Based on Untargeted Metabolomics
摘要：A method of non-targeted metabolomics coupled to ultra-high performance liquid chromatography-high resolution mass spectrometry was used to investigate effect of temperature on the metabolism of aspergillus flavus. Multivariate statistical analysis on the metabolomics data was carried out by using chemometric methods of OrthoPLS-DA(alternative partial least squares discriminant analysis) etc. The metabolism characteristics of aspergillus flavus were identified by MS/MS and library searching. In the study,the non-targeted metabolomics analytical method was validated by using internal standard and pooled quality control samples. The method was applied to investigate the effect of temperature on the metabolome of aspergillus flavus,and 3593(T-test,p<0.01) differential metabolites were found under different temperature conditions. Twenty candidate biomarkers were screened out. The results showed that temperature significantly affected the biosynthetic pathways of tricarboxylic acid cycle,fatty acid,phenylalanine,tryptophan and tyrosine, and regulated the secondary metabolites biosynthetic pathway enzymesactivity of aflatoxin,cyclopiazonic acid and kojic acid. This study provided a new insight for risk assessment and early warning research of aflatoxin in China.关键词：aspergillus flavus;metabolomics;high-resolution mass spectrum;aflatoxins biosynthesis;temperature- 669
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发布时间： - 摘要：A method of advanced polymer chromatography(APC) was established for the determination of the molecular weights and their distributions of polyethylene glycol derivatives and the impurity contents, with monomethoxy polyethylene glycol propyl aldehyde(mPEG_pALD) as the representation for polyethylene glycol derivatives. The chromatographic conditions such as chromatographic column and mobile phase were optimized, while the effects of the concentration of sample(within the concentration range of 0.5-20mg/mL) and dissolution time were also investigated. The optimized chromatographic conditions were as follows: three ultra-high performance gel columns were connected in series at 40 ℃ with methanol-water(95∶5,by volume) as mobile phase at a flow rate of 0.5mL/min,and a refractive index detector was selected. The result showed that the weight-averaged molecular weight(Mw) of mPEG_pALD was 19444 and its distribution index(D) was 1.01,while the Mw for impurity 1 was 38703 with its D index of 1.01 and its content of 1.31%,and the Mw for impurity 2 was 61036 with its D index of 1.00 and its content of 0.70%.Compared with the traditional GPC method, this APC method could obtain the molecular weight and its distribution of mPEG_pALD with higher resolution and less time, and the content of impurity could also be acquired. The method provides a scientific basis for the research, development and quality control of PEG derivatives, and is applicable for the determination of molecular weight, molecular weight distribution and purity of other PEG derivatives.关键词：ultra high performance gel chromatography;polyethylene glycol derivatives;relative molecular weight;impurity content;mPEG_Pald
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发布时间： - 摘要：In this paper, citric acid was used as carbon source for preparing fluorescent carbon quantum dots(CQDs). Due to the obtained CQDs had carboxyl groups on their surfaces,Man-CQDs were synthesized by immobilizing 4-aminopheny-l-α-D-mannopyanoside on the surfaces of CQDs via covalent bond.Furthermore,the binding constants of Man-CQDs and Escherichia coli JM109/Escherichia DH5a/Salmonella typhimurium S.123443 were obtained by fluorescent competition experiments.The results showed that the sizes of CQDs were approximately 26nm,the maximum excitation wavelength for CQDs was 445nm and the fluorescence yield was 76% in contrast to 54% quinine sulfate. Compared with the fluorescence intensity of CQDs,the prepared Man-CQDs remained unchanged in principle. By the Phenol-sulfate method, the concentration of Man-CQDs was calculated to be 2.832mmol/L,and the content of mannose in Man-CQDs nanoparticles was approximately 40%.Based on competition binding experiments of Man-CQDs and D-mannose with bacteria, the binding constant of Man-CQDs and bacteria was calculated by Scatchard equation, namely the binding constants of Man-CQDs with Escherichia coli JM109 and Salmonella typhimurium S.123443 were 2.39×103L/mol and 1.17×105L/mol,respectively. However, the reaction of Man-CQDs and Escherichia coli DH5a was nonspecific binding. The results suggested that the proposed method was applicable for the determination of noncovalent binding constant between mannose and bacteria. Besides, it offered a valuable reference information for the research of interaction between carbohydrate and bacteria.关键词：Man-CQDs;Escherichia coli JM109;Escherichia coliDH5a;Salmonella typhimurium S.123443;binding constant;interaction;fluorescence spectrum
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发布时间： - 摘要：An activated glassy carbon electrode(A-GCE) was prepared by using simple cyclic voltammetry(CV) scanning clean glassy carbon electrode(GCE) in 1.0 mol?L-1 H2SO4 solution.In 0.1 mol?L-1 pH 7.0 phosphate buffer solution(PBS),A-GCE not only improved the oxidations of ascorbic acid(AA),dopamine(DA),uric acid(UA) and nitrite(NO-2),but also resolved the weak and overlapped voltammetric responses of AA,DA,UA and NO-2 into four sensitive oxidation peaks.The peak potential differences(ΔEp,a) of AA-DA,DA-UA and UA-NO-2 were 0.16 V,0.15 V and 0.45 V,respectively,indicating that A-GCE has a good electro-catalytic response towards AA，DA，UA and NO-2.Thus,the A-GCE could be used for the simultaneous determination of AA,DA,UA and NO-2 in their mixture.Under the optimized experimental conditions,the linear dependences of DPV current responses for AA,DA,UA and NO-2 were observed in the concentration ranges of 5-2 100，2-140，1-700,10-1 050 μmol?L-1,with correlation coefficients of 0.998 9，0.996 8，0.997 4 and 0.997 8,respectively.The detection limits for AA,DA,UA and NO-2 were 0.19，0.45，0.28,0.72 μmol?L-1,respectively.The A-GCE was applied in the simultaneous determination of AA,DA,UA and NO-2 in serum samples with satisfactory results.关键词：electro-activated glassy carbon electrode;ascorbic acid;dopamine;uric acid;nitrite
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发布时间： - 摘要：In this paper,the electrochemical behavior of furosemide(FUR) at 3-anminopro-pyltriethoxsilane(APTS) and graphene(RGO) modified carbon paste electrode(APTS-RGO/CPE) was studied.The experimental results indicated that compared with CPE,APTS-RGO/CPE showed a good promotion towards FUR electrochemical oxidation,and the oxidation peak current increased significantly.Cyclic voltammetry(CV) and chronoamperometry(CA) were used to determine the reaction kinetics parameters of FUR on the APTS-RGO/CPE electrode.The relationship between FUR oxidation peak current and its concentration was evaluated by differential pulse voltammetry(DPV).The oxidation peak current of FUR and its concentration has a good linear relationship in the concentration range of 1.3-330 mg/L with the limit of detection(S/N=3) of 1.1×10-2 mg/L.The proposed method was successfully applied in the determination of commercial tablet samples,with their relative standard deviations of 0.4%-4.4%and recoveries of 98.5%-99.7%.The results were in accord with the requirement of quantitative detection.关键词：furosemide;3-anminopro-pyltriethoxsilane;graphene;modified carbon paste electrode;electrochemical determination
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发布时间： - 摘要：Headspace solid-phase microextraction(HS-SPME) combined with gas chromatography-triple quadrupole mass spectrometry(GC-MS/MS) was used for the rapid determination of 11 amide herbicide residues in tea.Various factors affecting extraction performance such as the types of extraction coatings,the type of inorganic salt,water consumption,salt dosage,extraction temperature and extraction time in HS-SPME were optimized by using the all fermented black tea matrix.Under the optimized conditions,four kinds of teas,i.e.geen tea,oolong tea,black tea and puer tea were selected for methodology validation.The results showed that the calibration curves of 11 amide herbicides were linear in the range of 1-1 000 μg/kg,with correlation coefficients(r2) of 0.992 5-0.999 9,and the limits of quantitation ranged from 1 μg/kg to 10 μg/kg.The average recoveries of the 11 pesticides in black tea,green tea,oolong tea and dark tea at three spiked levels were in the ranges of 70.3%-119.1%,85.2%-118.7%and 74.6%-113.3%,respectively.The relative standard deviations(RSDs) were all not more than 17.4%(n=5).With the advantages of simplicity,rapidness,high sensitivity and good reproducibility,the method could meet the requirements of detection of 11 amide herbicide residues in tea.关键词：headspace solid-phase microextraction(HS-SPME);gas chromatography-triple quadrupole mass spectrometry(GC-MS/MS);amide herbicides;tea
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发布时间： - 摘要：An ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometric(UPLC-Q-TOF-MS) method with purification of aflatoxin immunoaffinity column was established for the determination of aflatoxin B1(AFB1) in fermented dark tea.The sample was extracted with methanol-water(7∶3,by volume),and separated with an HSS T3 column(100 mm×2.1 mm,1.8 μm),then scanned in positive ion scanning mode and analyzed in Full ms-dd-MS/MS mode.The results showed that there existed good linearities for aflatoxin B1 in 33 kinds of fermented dark tea in corresponding concentration range,with their correlation coefficients all greater than 0.999.The recoveries were in the range of 86.4%-98.0%with the relative standard deviations(RSDs) of 0.3%-1.7%.The limits of detection(LODs,S/N≥3) and the limits of quantification(LOQs,S/N≥10) were 0.06 μg/kg and 019 μg/kg,respectively.This method was used to detect AFB1 in 33 tea samples collected from the local markets,and negative results were obtained.The results showed that the contents of AFB1 were within a reasonable range.This method was accurate,rapid and simple,and was suitable for the daily detection of AFB1.关键词：ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry;fermented dark tea;aflatoxin B1;rapid detection
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发布时间： - 摘要：A method was established for the determination of three tetracycline antibiotics(TCs) residues such as oxytetracycline,tetracycline and chlortetracycline in pig kidney by high performance liquid chromatography(HPLC) coupled with dispersive liquid-liquid microextraction(DLLME).The influences of dispersant type,amount of ionic liquid,amount of dispersant,pH of sample solution,extraction time and effect of salts on extraction efficiency were investigated.The optimum experimental conditions were as follows:using acetone as the dispersant,a 50 μL ionic liquid(［BMIM］ PF6),a 140 μL dispersant,a pH 3.0 sample solution,a 15 min of extraction time and no salt.The results showed that this method provided a wide linearity in the range of 0.1-10.0 mg/L with correlation coefficients no less than 0.999 5.The relative standard deviations(RSDs) were 2.2%-3.1%for oxytetracycline,tetracycline and chlortetracycline.The detection limits(LOD) were in the range of 54-93 μg/L with the enrichment folds of 7.0-27.8,and the recoveries were 99.5%-101.1%.It was found that the accuracy and precision could meet the requirements for the rapid,green,sensitive and accurate detection of oxytetracycline,tetracycline and chlortetracycline residues in pig kidney.关键词：ionic liquid(IL);dispersive liquid-liquid microextraction(DLLME);high performance liquid chromatography(HPLC);tetracycline antibiotics(TCs);pig kidney
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发布时间： - 摘要：A high performance liquid chromatography-tandem mass spectrometric(HPLC-MS/MS) method was developed for the determination of five nitromidazoles in aquatic products.Samples were extracted with acetonitrile containing 0.1%(by volume) ammonium hydroxide,and then purified with a mixture of anhydrous sodium sulfate,C18-N and NH2-PSA.The analysis was performed by an HPLC-MS/MS system with Merck Chromolith Performance RP-18e(4.6 mm×100 mm) column.The mobile phase consisted of methanol and 0.1%(by volume) formic acid solution by gradient elution,and multiple reaction monitoring(MRM) mode with positive electrospray ionization was used.The effects of the dosages of ammonium hydroxide in extractant and anhydrous sodium sulfate,C18-N and NH2-PSA in cleaning-up agent were studied.Under the optimized analytical conditions,the calibration curves for five nitromidazoles were linear in the concentration range of 20-500 μg/L with their correlation coefficients(r2) not less than 0.998 9.The recoveries at three concentrations ranged from 77.2%to 94.8%with the LOQs of 0.7-2.0 μg/kg.The method is suitable for the determination of 5 nitromidazoles in aquatic products.关键词：high performance liquid chromatography;tandem mass spectrometry;dispersive solid phase extraction;nitromidazole;aquatic product
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发布时间： - 摘要：To screen and quantify 31 carbamate pesticide residues in feed simultaneously,an ultra performance liquid chromatography-orbitrap mass spectrometric method and the target compounds data base were established.The feed sample was extracted with 100 mol/L HCl-methanol(1∶3).The extract was high-speedily centrifuged,purified with acid,then diluted and injected for analysis.Thermo Syncronis C18 column(150 mm×2.1 mm,3 μm)was chosen as the solid phase with 0.1%formic acid and 0.1%formic acid acetonitrile as liquid phase by gradient elution.The mass spectrometer was operated in positive scan mode.One pair of parent ion and daughter ion were chosen for qualitation,and the response of the parent ion was used to achieve the quantitation.Under the optimal conditions,31 carbamates were separated well.Good linearities were obtained in their respective quantitative ranges with correlation coefficients(r2) more than 0.98.The average recoveries were in the range of 50.6%-109%and the relative standard deviations(RSDs) were not more than 8.9%.The method was convenient,economical,sensitive and accurate,and was applicable for the qualitation and quantitation of 31 carbamate pesticide residues in feed.关键词：carbamate pesticides;ultra performance liquid chromatography;orbitrap mass spectrometry;qualitation and quantitation;feed
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发布时间： - 摘要：The interaction between D-mannose and concanavalin(ConA) was always used as a model target for protein-carbohydrate interactions.A simple,sensitive electrochemical impedance spectroscopy(EIS) biosensor was herein reported for the detection of ConA based on neoglycoproteins.D-mannose was covalently attached to a carrier protein,bovine serum albumin(BSA) to generate multivalent neoglycoproteins by the Maillard reaction.The biosensor was designed by immobilizing the neoglycoproteins on the surface of glassy carbon electrode,whose structures were recognized by concanavalinA(ConA).Since the neoglycoconjugates were easily prepared,a large number of D-mannoses could format multivalent complexs with ConA.The biosensor was highly sensitive.The increase of the electron transfer resistance of the biosensor was in logarithmically direct proportion to the concentration of ConA in the range of 5.0×10-11-5.0×10-9 mol/L.The detection limit for ConA was 1.7×10-11 mol/L,with an affinity constant Ka of 2.6×106 L/mol.The method developed in this study may be a promising approach,and could be extended to the design of an EIS biosensor for highly sensitive and rapid detection of other desired carbohydrate-protein interactions.关键词：EIS biosensor;protein-carbohydrate interactions;neoglycoproteins;ConA
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发布时间： - 摘要：A new method for the determination of acetaminophen was established by flow injection technique as CeO2 nanoparticles(CeO2 NPS) could effectively enhance the chemiluminescent(CL) intensity of luminol-KMnO4 system in alkaline conditions.In this study,a variety of factors influencing the chemiluminescence detection signal were studied,while the possible CL mechanism was discussed.Under the optimum experimental conditions,the concentration of acetaminophen was linear with the inhibition of relative CL intensity in the range of 1.0×10-7 mol/L-5.0×10-5 mol/L.The detection limit(3σ) was 3.3×10-8 mol/L.And the relative standard deviations(RSD) were calculated to be 0.3% for 11 times parallel detection on 5.0×10-6mol/L acetaminophen solution.The method was successfully applied in the determination of acetaminophen in Yinqiao tablets and urine with the satisfactory recoveries of 98.0% and 97.9%-98.7%,respectively.关键词：luminol;CeO2 nanoparticles;acetaminophen;flow injection;chemiluminescence
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发布时间： - 摘要：A method was developed for the analysis of 7 alkaloids in mainstream cigarette smoke aerosol by gas chromatography-mass spectrometry.By using electrical low-pressure impactor(ELPI),particles of cigarette smoke aerosol were divided into 12 stages and collected.The content and concentration distributions of 7 alkaloids with respect to smoke aerosol particle size were investigated.The collected aerosol particles were treated by alkali extraction method with sodium hydroxide solution and dichloromethane.The extract was separated with a DB-5MS capillary column under selected ion monitoring(SIM) mode.The targets were quantitatively analyzed using internal standard method.The results showed that,the relative standard deviations(RSDs) for the established method ranged from 2.1%to 6.4%,with limits of detection(LODs) of 0.39-14.84 ng/cig,and the recoveries at three spiked levels ranged from 85.5%to 124.8%.All of 7 alkaloids mainly distributed in aerosol of medium size particles(0.144-0.722 μm) with a peak content at particle size of 0.431 μm,which was similar to the distribution pattern of collected particle mass.The concentrations of 7 alkaloids were uniform throughout the particles of various sizes,indicating a non-specificity distribution.关键词：mainstream smoke;aerosol;alkaloids;size distribution;gas chromatography-mass spectrometry
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发布时间： - 摘要：(2-Hydroxybenzylidene)-1-(quinolin-2-yl)-9H-pyrido-［3,4-b］ indole-3-carbohydrazide(QCS) was synthesized by a series of reactions with L-tryptophan methyl ester hydrochloride and 2-quinolinecarboxaldehyde as raw material. The structure of QCS was characterized by 1H NMR,13C NMR and ESI-MS. The probe QCS has a specific response to Al3+,and the limit of detection was 4.40×10-9 mol/L. QCS showed a good linearity in the concentration range of 9-100 μmol/L with a correlation coefficient(r2) of 0.999 1. In a mixed system of ethanol-water(9∶1,by volume),the binding ratio of QCS and Al3+ was 1∶1,and the complexing constant was proved to be(2.91±0.22)×103(mol/L)-1 in the fluorescence titration spectra. Furthermore,the fluorescent intensity of QCS-Al3+ maintained stable in the pH 5.0-8.0,which satisfied the requirements for detection on environmental water samples and living cells.关键词：β-carboline;quinolone;schiff base;Al3+fluorescent probe
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发布时间： - 摘要：The main sources of uncertainty in heating capacity measurements tested by air enthalpy method were analyzed in this paper.Type A and Type B analyses were carried out for uncertainty evaluation through mathematical model.The mathematical models for the main components of uncertainty of heating capacity were deduced and established based on difference of static air pressure,air enthalpy value,air specific volume and air humidity.The heating capacity measurement uncertainty was calculated based on experimental data,and the complex uncertainty components were evaluated by limit method.Thus,a convenient and reliable method was provided to evaluate the uncertainty for heating capacity measurement.关键词：air-source heat pump;air condition;heating capacity;air enthalpy value;uncertainty
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发布时间： - 摘要：A pentacyclic hemiacetal steroid was isolated and purified by chromatography with silica gel,Sephadex LH-20 column as well as HPLC.Its plane structure was identified by nuclear magnetic resonance spectroscopy(NMR spectra)and mass spectrometry.By determining and comparing the calculated values of CD,it is determined that the structure of the compound is(8R,9S,10R,13R,14S,17R,18R,20S,22R)-cholesta-1,4-dien-18-al,22-hydroxy-3-oxo-,cyclic 18,22-(acetyl acetal).The compound was isolated from Sinularia sp.for the first time.关键词：coral;pentacyclic hemiacetal steroid;structure elucidation
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发布时间： - 摘要：With the advantages of small size,portabilityand anti-electromagnetic interference,fiber optic surface plasmon resonance(FO-SPR) biosensor could be applied in biological,chemical,pharmaceutical and food detections.In this paper,the recent progresses on the structures,film components and new applications of FO-SPR biosensor are summarized .In general,the reflection type and online transmission type are the two most important structures of the biosensor.Moreover,the commonly used films are gold film,silver film,composite film and metal nanoparticles.Based on the features of real-time analysis,anti-electromagnetic interference and multichannel detection,the future development and applications of FO-SPR biosensor are put forward.关键词：optical fiber;surface plasmon resonance(SPR);biosensors;interaction;film components
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发布时间： - 摘要：Chemiluminescence immunoassay is widely used in the rapid detection of microbes because of its high sensitivity of chemiluminescence and high specificity of immune response.In the paper,the advance of the coresystems of chemiluminescence immunoassay in microbiological detection is emphatically illustrated.The related sample pretreatments and the new detection methods are reviewed.Although Chemiluminescence immunoassay in the microbiological detection has the advantages of rapidness and low consumption,its specific recognition and sensitivity could be further improved.The innovative luminescence systems,the luminescence amplification methods,the alternative recognition elements and the related pretreatment techniques are the focuses in future research.关键词：chemiluminescence immunoassay;microbiological detection;pretreatment;luminescence amplification;recognition element
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