最新刊期
卷 35 ， 期 5 ， 2016
- 摘要：Based on high performance liquid chromatography combined with time of flight mass spectrometry(HPLC-TOF MS),the metabolomics method was established to evaluate the urine samples collected from 30 farmers,an occupational exposure population in Zhouwang village,Shanxi province,P.R.China.These people were exposed to a circumstance with acetamiprid,lambda-cyhalothrin,bifenthrin acetate and methyl amino abamectin benzoate.The urine samples were detected before the exposure,and at the first day,the third day,the fifth and seventh day after the exposure. Extracting 10 common metabolites in urine and quality control samples showed that the method has high precision and reliability.Principal component analysis(PCA) score plot was used to separate the urinary metabolic profiles from the different time urine sample,and the results showed that the urine metabolic profiles before and after the exposure to pesticide were obvious different.36 different ions were found by PCA loading plot model,in which 8 ions were identified by retrieving metabolites database and identified with standard.The most statistically significant changes were observed for dopamine,serotonin,tyrosine,tryptophan,taurine and hippuric acid(downward trend),canine urea and creatine(upward trend).This work suggests that an exposure to pesticide mixtures induces metabolism disturbance.It is inferred that the pesticide mixtures could lead to tryptophan metabolism intermediates decreased,accumulation of hepatic and energy metabolism change may related with the nervous system and liver function damage.These changes of metabolites existed in nervous and liver system are consistent with the mechanism of four kinds of pesticides which could cause damage to insecticidal nervous system.关键词：pesticide mixtures;metabolomics;high performance liquid chromatography-time of flight mass spectrometry(HPLC-TOF MS);biomarkers
- 2065
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- 1437
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- 1
发布时间： - 摘要：Poly(p-phenylenediamine) nanosheets were first synthesized through oxidative polymerization of p-phenylenediamine,and then used as the substrate for anchoring copper microspheres via a facile solvothermal route.The resultant copper/poly(p-phenylenediamine)(Cu/PpPD)composites possess good electrical conductivity,big specific surface area,large pore size and pore volume,which are beneficial for transfer of electrons,utilization of active sites and transportation of reactant and electrolyte.The as-prepared Cu/PpPD composites showed excellent electrocatalytic activity toward the direct oxidation of glucose in the absence of any enzymes.Under the optimal conditions,the Cu/PpPD-based enzymeless glucose sensor showed the advantages of short response time(i.e.,the current achieved 95% of the steady state value within 3s),wide linear range(0.003-6.44mmol/L),high sensitivity(929μA?mmol-1?L?cm-2),low detection limit(4.48×10-7mol?L-1),good reproducibility and selectivity.In addition,the as-prepared Cu/PpPD-based enzymeless glucose sensor was successfully applied in the quantitative determination of glucose in real serum samples with recoveries of 99.5%-101.1%,which indicated it has a great prospect in clinical application.关键词：poly( p-phenylenediamine);copper microsphere;glucose;non-enzyme sensor
- 1940
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- 1257
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- 3
发布时间： - 摘要：An effective method was established for the analysis of metabolomics in rice from different geographical origins by gas chromatography-quadrupole time-of-flight-mass spectrometry(GC/Q-TOF MS)，and was applied in geographic authenticity identification of rice.D-optimal experimental design was used to optimize the different extraction solvents，and the extraction efficiency was evaluated by partial least squares(PLS).Effects of derivatization reagents，derivatization temperature and time on the analysis of metabolites were investigated.The best result was obtained using methanol-water(1∶1) as extraction reagent，and derivatizing with N-methyl-N- (trimethylsilyl) trifluoroacetamide-trimethylchlorosilane(MSTFA-TMCS,99∶1) at 60℃ for 1h.10 highly matched metabolites were selected to assess the precision，reproducibility of the method and the stability of derived products.Satisfactory results were obtained with relative standard deviations(RSD) lower than 9%，confirming reliability of the method.Principal component analysis(PCA) prediction model was establised by mass profiler professional(MPP) to classify the Suijing 4 rice from four different geographical origins in Heilongjiang Province，and the results showed that samples from different places clustered into four different groups significantly.11 differential compounds were determined，which satisfied P<0.05 and a fold change cut-off ≥2.This demonstrates the feasibility of the developed analysis method in rice by GC/Q-TOF MS and its application in geographic authenticity identification of rice combined with PCA analysis.The method could provide a scientific basis for the standardization of rice market and the utilization of the resources.关键词：rice;gas chromatography-quadrupole time-of-flight-mass spectrometry(GC/Q-TOF MS);metabolomics;principal component analysis(PCA);geographic authenticity
- 2195
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- 3
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- 4
发布时间： - 摘要：The water soluble carbon dots were prepared by hydrothermal reaction with arabia sugar and casein phosphopeptides.Transmission electron microscopy(TEM)，ultraviolet absorption spectroscopy(UV)，fluorescence spectroscopy(FL) and infrared spectroscopy(FTIR) and X-ray diffraction(XRD) were used to characterize the particle size，absorption spectra，luminescence properties and surface groups of the carbon dots.The FL intensity changes in the presence of representative metal ions under the same conditions were investigated to evaluate the selectivity of the carbon dots.The results showed that the average particle size of the fluorescent carbon dots is 4.62nm,and its maximum absorption wavelength is 281nm.The fluorescent carbon dots could emit bright fluorescence in the ultraviolet light with maximum emission wavelength of 414nm.The carbon dots have good water solubility，and the fluorescence emission spectrum is red shift with the increase of the excitation wavelength.FTIR spectra analysis revealed the presence of —COOH，—NH2 and —OH groups are on the surface of the carbon dots，and the XRD peak is about 21°.Tremendous FL intensity decrease was observed by addition of Cu2+ and Fe3+.The reason may be that the ions caused the aggregation of the fluorescent carbon dots，leading to the decrease of fluorescence intensity.The carbon dots are expected to be used as a fluorescent probe for analysis and biological imaging.关键词：carbon dots;fluorescence property;fluorescent probe;metal ion
- 1893
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- 1169
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- 2
发布时间： - 摘要：An ultra performance liquid chromatography-tandem mass spectrometric(UPLC-MS/MS) method was established for the simultaneous determination of abietic acid,acetyl-11-keto-β-boswellic acid and Sudan Ⅰ-Ⅳ in traditional Chinese medicine.The sample was extracted with methanol,and then separated on a Zorbax SB-C18(3.5μm,2.1mm×150mm) chromatographic column using a mixture of acetonitrile and 0.1% formic as mobile phase by gradient elution at a flow rate of 0.3mL/min.The electrospray was operated in the positive mode under the multiple reaction monitoring(MRM) mode,and the quantitation was carried out by the matrix standard curve.As a result,the calibration curves for Sudan Ⅰ/Ⅱ were linear in the range of 3.0-100μg/L,and for the others were linear in the range of 30-1000μg/L.The correlation coefficients for all the compounds were greater than 0.99.The limits of detection(LOD) ranged from 0.7μg?kg-1 to 8.6μg?kg-1,and the limits of quantitation(LOQ) ranged from 2.2μg?kg-1 to 25.1μg?kg-1.The average recoveries of six compounds at three spiked levels were in the range of 76.5%-94.9% with relative standard deviations(RSD) of 2.3%-9.9%.It was demonstrated that the first peak would not appear if the sample was kept in methanol-5% formic acid solution which could be avoided 10% errors in quantitative analysis for Sudan Ⅲ and Sudan Ⅳ. Moreover, the mass spectrometric behaviour and the ion fragmentation patterns of six compounds could provide beneficial references for the qualitative identification and quantitative analysis.This method is simple,rapid and accurate,and is suitable for the rapid determination of abietic acid,acetyl-11-keto-β-boswellic acid and Sudan Ⅰ-Ⅳ in traditional Chinese medicine.关键词：ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS);abietic acid;acetyl-11-keto-β-boswellic acid;Sudan Ⅰ-Ⅳ;traditional Chinese medicine
- 2044
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- 1185
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- 1
发布时间： - 摘要：A rapid and accurate method was developed for the analysis of 43 pesticide residues in tobacco based on gas chromatography-time of flight mass spectrometry(GC-TOF MS).By modified QuEChERS method,tobacco samples were extracted with acetone-hexane(1∶1),and cleaned up with primary secondary amine(PSA),then detected by GC-TOF MS.Precise mass database of characteristic ions by TOF MS,coupled with retention time,fragment ion abundance ratios,fragmentation patterns of characteristic fragment ions,isotopic peak clusters were employed for the qualitative identification of pesticides.The quantatative method was established using the matrix matched calibration standards with triphenyl phosphate(TPP) as the internal standard.The results indicated that the linear correlation coefficients(r2) were not less than 0.993 with relative standard deviations(RSD) not more than 9.6%,and quantitation limits of 1.3-5.0 μg/kg.The recoveries of 43 pesticides at three spiked concentration levels ranged from 76.4% to 96.6%.The method is simple,rapid,accurate and sensitive,and is appropriate for the determination of multi-residues in tobacco.关键词：tobacco;pesticide;QuEChERS;electron impact ionization;gas chromatography;TOF MS
- 2242
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- 1176
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- 4
发布时间： - 摘要：A method was established for the quantitative determination of 20 organochlorine pesticides(OCPs) in crayfish by gas chromatography and mass spectrometry(GC-MS)．The preparation and analytical conditions，such as extraction solvent，purification method and other analytical conditions were optimized．The samples were extracted with acetonitrile，and kept in constant volume with ethyl acetate-cyclohexane(1∶1).The extract was purified by gel permeation chromatography(GPC) combined with solid-phase extraction(SPE),and determined by GC-MS under selective ion scan(SIM) mode．Under the optimum conditions，the calibration curves of the compounds were linear in the range of 0.01-1.0 mg/L with correlation coefficients higher than 0.994，and the limits of detection(LOD,S/N=3) were in the range of 0.1-1.5 μg/kg．The recoveries of target compounds in crayfish yellow and meat samples at three spiked concentration levels of 5，10，20 μg/kg were in the range of 71.3%-117.3%，with RSDs(n=6) of 0.6%-7.5%．The method is sensitive，accurate and simple，and could be applied in the determination of 20 OCPs in crayfish. Key words：gas chromatography-mass spectrometry(GC-MS)；crayfish；organochlorine pesticides(OCPs)；gel permeation chromatography(GPC)；solid-phase extraction(SPE)；residue关键词：gas chromatography-mass spectrometry(GC-MS);crayfish;organochlorine pesticides(OCPs);gel permeation chromatography(GPC);solid-phase extraction(SPE);residue
- 2074
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- 1159
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- 2
发布时间： - 摘要：A simple and sensitive electrochemical method was developed for the determination of 3,3′5,5′-tetrabromobisphenol A(TBBPA) based on Ag-loading white carbon black composites modified carbon paste electrode(Ag-SiO2/CPE).Ag-SiO2 composite was synthesized and its morphology and structure were characterized by scanning electron microscopy(SEM),fourier infrared spectrometry(FT-IR) and X ray photoelectron spectroscopy(XPS).The electrochemical property of Ag-SiO2/CPE was characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS).Futhermore,CV and linear sweep voltammetry(LSV) were proposed to study the electrochemical oxidation behavior of TBBPA at the modified electrode.The CV results showed that,compared with bare electrode,the modified electrode displayed an enhanced electrocatalytic activity toward the oxidation of TBBPA with a well defined cyclic voltammetric peak.Conditions influencing the detection process such as content of modifier,pH value of buffer solution and scan rate were optimized.Also,the repeatability,stability and selectivity were further studied.Under the optimized conditions,the oxidation current increased linearly with the increase of TBBPA concentration in the ranges of 0.010-0.10 μmol/L and 0.10-25 μmol/L,and the detection limit(S/N=3) was found to be 1.9 nmol/L.The proposed method was applied in the direct determination of TBBPA in electronic products with satisfactory results,and the recoveries were in the range of 96%-103%.The results agreed quite well with those obtained by capillary electrophoresis(CE).关键词：Ag-loading white carbon black composites;3,3′,5,5′ tetrabromobisphenol A;electrochemistry;electronic product
- 1933
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- 1009
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- 2
发布时间： - 摘要：One suspected phosphodiesterase-5 inhibitor(PDE-5) derivative was found in a kind of medicinal liquor by UPLC-DAD-QTOF-MS.Sample purification was carried out by a preparative HPLC system，and its structure was determined by NMR,IR and UPLC-DAD-QTOF-MS methods.The results showed that the compound is a new aildenafil derivative which has never been reported at home and abroad.关键词：PDE-5 inhibitor analogue;UPLC-QTOF-MS;NMR;IR;structure identification
- 2043
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- 1160
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- 4
发布时间： - 摘要：Gas chromatography-mass spectrometry was used to determine the fatty acid compositions in five different animal oils,and chemometric methods(such as principal component analysis(PCA),cluster analysis(CA) and discriminant analysis(DA)) were applied to the obtained data.The fatty acids in five animal oils samples were investigated,and the results showed that the main compositions of animal oils were C16∶0,C18∶0,C18∶1c-9,C18∶2c-9,12 and C14∶0.Total contents of the five major fatty acids were 92.1%,93.5%,93.5%,90.6%and 95.6%corresponding to the chanterelle,butter,duck fat,suet and lard,respectively.The ratios of unsaturated and saturated fatty acids(U/S) were all less than 1 for five animal oils.Three PCs were sequentially used for CA and DA.Three discriminant functions were established and the correlation coefficients were larger than 0.995.The initial classification accuracy and cross-validation accuracy of chanterelle,butter,duck fat,suet and lard all reached up to 100%.关键词：animal oils;gas chromatography-mass spectrometry(GC-MS);principal component analysis;cluster analysis;discriminant analysis
- 2076
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- 1182
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- 6
发布时间： - 摘要：A new modified electrode(p-PTA/CS-AB/GCE) was prepared with phosphor-tungstic acid,chitosan and acetylene black.The electrochemical behaviors of chloramphenicol(CAP) on p-PTA/CS-AB/GCE were investigated by cyclic voltammetry(CV).The results showed that there was an obvious reduction peak of CAP on the modified electrode in pH 6.0 PBS buffer solution and the reduction peak current was linear to the scan rate in the range of 40-400 mV/s,indicating that the electrode process of CAP was controlled by absorption.The different concentrations of CAP were determined by differential pulse voltammetry,and a good linear relationship was observed between reduction peak current and CAP concentration in the range of 5.0×10-7-1.0×10-4 mol/L.The detection limit(S/N=3) was 5.13 ×10-8 mol/L.The mothed was applied in the determination of CAP in chloramphenicol tablet sample,with relative standard deviation of 14%and recoveries of 97.7%-105.1%.关键词：chloramphenicol;phospho tungstic acid;chitosan;acetylene black;differential pulse voltammetry;modified electrode
- 2098
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- 1108
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- 2
发布时间： - 摘要：A rapid method was developed for the determination of organophosphorus pesticides residues in vegetables using GC-MS coupled with direct single drop microextraction(SDME).The samples were extracted and enriched by direct SDME,then the target compounds were analyzed by GC-MS under selected ion monitering(SIM) mode,and quantified by the internal standard.Under the optimized conditions,9 kinds of organophosphorus pesticides,including sulfotep,phorate,iprobenfos,methyl parathion,ronnel,malathion,chlorpyrifos,isocarbophos and quinalphos,were successfully separated.The correlation coefficients were not less than 0.995 8,and the detection limits ranged from 0.32 μg/kg to 0.91 μg/kg.The recoveries were in the range of 83.2%-1345% with RSDs(n=5) of 3.4%-16.5%.The developed method was simple,rapid and sensitive,and could be applied in the determination of 9 kinds of organophosphorus pesticides residues in vegetables.关键词：direct single-drop microextraction;organophosphorus;rapid;gas chromatography-mass spectrometry(GC-MS);vegetables
- 2016
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- 1117
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- 6
发布时间： - 摘要：Analytical methods were developed for the determination of hexamidine,chlorhexidine and their salts in cosmetics by ultra performance liquid chromatography(UPLC) and verification by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).Cosmetic samples of toning lotion,shampoo,powder and cream were firstly demulsificated with saturated sodium chloride solution,and wax type samples(e.g.lipstick) were dispersed with tetrahydrofuran.Water and methanol were then added successively,followed by thorough vortex oscillation.The extraction and clean up procedures were performed using ultrasound assisted extraction and solid phase extraction separately.Afterwards,chromatographic separation was conducted on an ACQUITY UPLC BEH C18 column(2.1 mm × 50 mm,1.7 μm) by a gradient elution of 0.1% aqueous trifluoroacetic acid solution and acetonitrile containing 0.1% trifluoroacetic acid.The detection was completed using a diode array detector(DAD).The external standard method was used for quantitation.Under the optimum conditions,good linearity(r2>0.999 6) was observed over a certain range of concentration.The limits of detection(LODs) and the limits of quantitation(LOQs) were 10 mg/kg and 20 mg/kg,respectively.The mean recoveries at three spiked levels ranged from 81.9% to 97.6%,with relative standard deviations(RSDs) of 0.9%-7.8%.This method was proved to be rapid,accurate,sensitive and high specified,and could be used in the practical determination of commercial cosmetics.关键词：hexamidine;chlorhexidine;solid phase extraction(SPE);ultra performance liquid chromatography(UPLC);mass spectrometric verification;cosmetics
- 2128
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- 6
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- 2
发布时间： - 摘要：A new method was established for the simultaneous determination of fourteen benzophenone and benzotriazole UV absorbents in textiles by solid phase extraction(SPE) combined with ultra-high performance liquid chromatography(UPLC).The samples were extracted with methanol-tetrahydrofuran by ultrasonic.After purified using ENVI Carb SPE column,the extract solutions were separated on a C18 chromatographic column using acetonitrile-0.1% formic acid as mobile system by gradient elution,and detected with diode array detector(DAD).The results indicated that 14 analytes presented favorable linearity(r＞0.999) in the concentration range of 0.1-50 mg/L.The limits of detection of the method(LODs,S/N=3) were in the range of 1-5 mg/kg.Recoveries were calculated to be in the range of 81.5%-99.1% at three spiked concentration levels in negative samples,with relative standard deviations(RSD,n=6) of 2.8%-7.5%.The method is simple,rapid,and is suitable for the simultaneous determination of fourteen UV absorbents in textiles with favorable recoveries and precision.关键词：ultraviolet absorbers;textiles;ultra-high performance liquid chromatography(UPLC);solid phase extraction(SPE)
- 2003
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- 1122
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- 2
发布时间： - 摘要：An ultra high performance liquid chromatographic(UPLC) method was established for the simultaneous determination of eleven benzophenone and benzotriazole UV absorbents in coating samples.The emulsion paint samples were firstly dispersed with water,and subsequently extracted with ethyl acetate,while the wood varnish samples were extracted directly with acetonitrile.The extracts were separated on a C18 chromatographic column using acetonitrile-water mobile system with a variable flow rate,and detected with diode array detector(DAD).The results indicated that 11 analytes had good linear relationships(r≥0.999 0) in the concentration range of 0.1-50 mg/L.The limits of detection of the method(MLODs) were in the range of 10-30 mg/kg.Recoveries of 11 analytes at three spiked concentration slevels were in the range of 80.7%-107% with relative standard deviations(RSD,n=6) of 3.0%-8.7%.The method was simple and rapid,and was suitable for the simultaneous determination of eleven UV absorbents in coating samples with favorable recoveries and precisions.关键词：ultraviolet absorbers;coatings;ultra high performance liquid chromatography(UPLC);variable flow elution;benzophenone;benzotriazole
- 2022
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- 1178
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- 3
发布时间： - 摘要：More attention has been given to developing a microporous material,metal-organic frameworks(MOF) with large surface area as an advanced separation media in the field of separation science.In this work,a novel metal-organic framework,{［Sm(L)(DMF)］?2(DMF)?5(H2O) }(MOF-Sm-L),with a one dimensional channel and active amido groups was chosen as stationary phase to prepare a capillary gas chromatographic column via a verified dynamic coating procedure to study the separation performance of linear alkanes,linear alcohols and substituted aromatics.The column could offer good separations for linear alkanes,linear alcohols,as well as aromatic positional isomers(e.g.cresol,hydroquinone,bromobenzonitrile,chloronitrobenzene and nitrotoluene).The separation behaviors of the column upon different organic substances may be related to the 1D pore structure of MOF-Sm-L,in which the van der waals forces between the compounds without hydroxyl and the hydrophobic inner surfaces might have great effect on separation of the compounds without hydroxyl,whereas the separation of the hydroxyl compounds was affected by(OH…O or OH…N) hydrogen bonds formed between the analytes and the active amido groups on the pore wall except for the van der waals forces.The effect of temperature on separation of aromatic positional isomers was investigated to elucidate entropy and enthalpy controlling of the separation process.关键词：metal-organic framework;gas chromatography(GC);separation;phenolic isomers
- 2054
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- 1072
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- 0
发布时间： - 摘要：In this paper,the quaternary ammonium salt(QAS-1) was prepared with N-methy imidazole and N-methyl diethanol amine.It was characterized by FT-IR,NMR and TOF-MS.Its antibacterial properties against S-aureus,α-H-tococcus,E-coli and P-aeruginosa were subsequently evaluated by paper disk method and shake culture method,which showed that it has a good antibacterial effect.Especially,the antibacterial effect against gram-negative bacteria(E-coli and P-aeruginosa) is more obvious and better than positive control(chlorhexidine).关键词：quaternary ammonium salt(QAS);N-methyl imidazole;antibacterial properties;cytotoxicity
- 1972
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- 1205
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- 1
发布时间： - 摘要：In the process of oily sludge treatment,it is important to simultaneously determine the water and oil contents rapidly and accurately,which is helpful to assess the oil recovery efficiency from the oily sludge and to optimize the process parameters on site.In this study,the calibration models of oily sludge samples were developed by the low-field nuclear magnetic resonance(LF NMR) together with the partial least square regression(PLSR) while the water and oil contents attained by Dean Stark apparatus as reference values.Both echo decay curves and T2 distribution curves were employed for the model construction to investigate the performance of the calibration model.In the end,the general calibration model with three sample sets was constructed.The results indicated that the model with echo decay curves is superior to that with T2 distribution curves.The general calibration model with echo decay curves was satisfactory with correlation coefficients(R2)of 0.965 7 and 0.978 5 for the water and oil contents,respectively.The corresponding RMSECV were 2.73% and 2.22%.The 3 batches of samples were used to verity the general model.The R2 of 0.914 1 and 0.924 7 was obtained for the water and oil contents,respcetively.The corresponding RMSEP of 1.85% and 2.04% was achieved,which was close to the RMSECV of 2.73% and 2.22%.The above results showed that the general model was steady and could meet the standards of accurate and rapid determination with the advantages of time-saving(less than 5 min),solvent-free,and non-invasion.关键词：oily sludge;waste treatment;nuclear magnetic resonance(NMR);water content;oil content;principal component analysis
- 1975
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- 980
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- 0
发布时间： - 摘要：A novel surface-enhanced Raman scattering(SERS) method was established for the quantitative determination of trace phosmet via potassium thiocyanate(KSCN) serving as an internal standard.The silver colloid with high SERS activity，a kind of SERS substrate，was prepared by sodium citrate reduction.The enhanced Raman signal of phosmet on silver colloid was proved through comparing the normal Raman spectra of silver colloid and phosmet with SERS spectrum of trace phosmet.The concentrations of phosmet could be determined with the corresponding SERS spectra produced by adsorption of phosmet on nano silver colloid surface，while KSCN was selected as the internal standard.The strongest SERS signal of phosmet appeared at 503 cm-1 ,and was assigned to the S—P stretching vibration，so it was considered as quantitative peak.The range linear of 5.0×10-7-1.2×10-5 mol?L-1 was obtained for concentrations of phosmet divided by ratio of S—P stretching vibration at 503 cm-1 and SCN- characteristic peak at 2 120 cm-1.The linear correlation coefficient(r) was 0.997 8,and the detection limit(S/N=3) was 2.82×10-7 mol?L-1.Furthermore，the proposed method was applied in the detection of simulated water sample，with recoveries of 88.7%-110.2% and relative standard deviations(RSD) not more than 8.0%.The interference experiments were also considered by the detection of some inorganic ions and the background SERS signal of simulated water sample.With the advantages of simplicity，easy operation and no interference of internal standard substance，the proposed method could be extended to the determination of other pesticide molecules.关键词：surface-enhanced Raman scattering;phosmet;internal standard method;silver colloid
- 2065
- |
- 1126
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- 7
发布时间： - 摘要：A new method was developed for the determination of three quaternary ammonium compounds(QACs) residues,including dodecyl dimethyl benzyl ammonium chloride(C12-BAC),hexadecyl dimethyl benzyl ammonium chloride(C16-BAC) and benzethonium chloride in ice creams using solid phase extraction(SPE) and ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The samples were melted and mixed,and then added into acetonitrile to extract target compounds and precipitate protein.The supernatant was purified with weak cationic exchange solid phase extraction cartridge(WCX) and concentrated in nitrogen stream.The separation of three quaternary ammonium compounds was performed on a Waters BEH HILIC column(50 mm×2.1 mm,1.7 μm) by isocratic elution using acetonitrile(containing 0.1% formic acid)-10 mmol/L ammonium acetate as mobile phase.The targets were analyzed under the multiple reaction monitoring(MRM)mode in positive electrospray ionization.The results showed that the calibration curves of three QACs were linear in the range of 0.5-20 μg/L with correlation coefficients greater than 0.999.The method quantitation limits(LOQs,S/N=10)of three analytes ranged from 3.0 μg/kg to 5.5 μg/kg.The average recoveries were in the range of 90.7%-102.2%,and the relative standard deviation(RSD,n=6) were 2.4%-6.4% at three spiked levels of standard.With the advantages of simplicity,accuracy,sensitivity and good reproducibility,the method could be used for the determination of QACs residues in ice creams. Key words：quaternary ammonium compounds;ice creams;ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS);solid phase extraction(SPE)关键词：quaternary ammonium compounds;ice creams;ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS);solid phase extraction(SPE)
- 2076
- |
- 1196
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- 2
发布时间： - 摘要：A novel analytical method was developed for the separation of tropane alkaloids by high performance liquid chromatography(HPLC) using ionic liquid(OminPF6) as mobile phase additive.The retention model and mechanism for the ionic liquid were also illustrated.The effect factors,including wavelength of detection,type and proportion of organic phase,pH value,type and concentration of ionic liquid and buffer salt system on retention behavior of components were investigated.The results showed that,the ionic liquid as mobile phase additive could significantly improve the separation effect on tropane alkaloids,and also increase the symmetry of peak and the relative separation.The results also showed that the relationship between capacity factor and concentrations of ionic liquid preferably complied with the stoichiometric displacement model for retention(SDM-R)，and the retention process of alkaloids was mainly based on competitive adsorption function.关键词：ionic liquid;high performance liquid chromatography(HPLC);tropane alkaloids;retention behavior;retention mechanism
- 2031
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- 1119
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- 3
发布时间： - 摘要：Aptamer is a subparagraph ligonucleotide sequence screened in vitro,and has a high affinity and strong specificity to combine with corresponding ligands.Thymine(T) bases can combine specially with Hg2+ to form the structure of T-Hg2+-T,which is more stable than the double helix of DNA.Based on this structure,an aptamer electrochemical sensor was fabricated to detect Hg2+,and it showed the advantages of high specificity,stability and sensitivity.In this paper,the developed aptamer electrochemical sensors for Hg2+ detection in recent years are summarized and reviewed.The fabrication processes and the detection mechanisms of this kind of sensors are reported in detail,the merit and demerit of the aptamer electrochemical sensor are analyzed.Finally,the developoing prospect for the sensors in the future are put forward,and 83 references are cited.关键词：aptamer;Hg2+;electrochemical sensor;review
- 1917
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- 1250
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- 5
发布时间： - 摘要：Mitochondria plays a key role in energy metabolism of cells,and the small changes of internal environment in mitochondria will affect the normal cell life activities.In the meanwhile,many active small molecules in mitochondria also play a key role in many physiological process.Therefore,visual monitoring of mitochondrial itself and its changes of the internal micro environment are of great importance for the research of biological phenomenon，disease diagnosis and treatment.Fluorescence method has been extensively used due to its advantages of simple operation,high sensitivity and selectivity,real time detection and little damage to organisms.The two photon fluorescent probe technique has shown a much broader application prospect in the field of life sciences compared to the one-photon fluorescent probe technique as it has many advantages,such as absorbing light of longer wavelength with lower energy but emitting shorter wavelength，high three-dimensional spatial selectivity，large penetration depth，avoidance of photodamage and photobleaching and lower tissue auto-fluorescence.The basic principle of organic two photon absorption and the research status of organic two-photon fluorescent probes for active small molecules in mitochondria were introduced,as well as the trends of organic fluorescent probes for active small molecules in mitochondria in the future were prospected.关键词：mitochondria;active small molecules;two-photon;fluorescent probes;detection;review
- 1920
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- 1184
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- 2
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