最新刊期
卷 32 ， 期 1 ， 2013
- 摘要：A convenient and sensitive method for the residue analysis of indoxacarb in tea and tea infusion was developed and validated by using ultra high performance liquid chromatography coupled with tandem mass spectrometry followed by(dispersive) solid phase extraction cleanup.The calibration curve was linear over the concentration range of 0.01-20.0 mg/L for indoxacarb,with a correlation coefficient(r) of 0.993 7,and the limit of detection(LOD) of 0.025 ng.The average recoveries of indoxacarb at three spiked concentration levels in different sample matrixes(made tea，tea infusion and fresh tea leave) ranged from 96% to 107% with relative standard deviations(RSDs,n=6) of 1.3%-7.8%.The limits of quantitation(LOQs) of indoxacarb were 5 μg/kg in tea and 0.10 μg/L in tea infusion,respectively.The proposed method was successfully applied in the degradation and final residue study of 150 g/L indoxacarb emulsifiable concentrates(EC) in the field treatment experiment,and the dissolution dynamic of indoxacarb from made tea to tea infusion was investigated for the risk assessment.The degradation half-life time of indoxacarb in fresh tea leaves was from 1.42 days to 2.47 days.And the total leaching rate of indoxacarb for the brewing processes from made tea to tea infusion for three times was lower than 10%.For the risk assessment,the MRL proposed at 3.0 mg/kg was safety for tea drinking with the pre-harvest intervals(PHI) of ten days.The estimated intake of indoxacarb was shown to be 0.619% of acceptable daily intake(ADI).关键词：indoxacarb;tea;tea infusion;(dispersive) solid phase extraction;ultra high performance liquid chromatography coupled with tandem mass spectrometry(UPLC-MS/MS);residue and degradation
- 2832
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- 2047
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- 12
发布时间： - 摘要：A simple and rapid method was developed for the simultaneous determination of 290 pesticide residues in tea.The sample was prepared by the modified QuEChERS(quick,easy,cheap,effective,rugged and safe) method,extracted with acetonitrile,followed by liquid-liquid partitioning formed by adding sodium chloride and anhydrous magnesium sulfate.The extract was separated on a Thermo Accucore aQ(100 mm×2.1 mm,2.6 μm) column,detected by high performance liquid chromatography-tandem mass spectrometry under multiple reaction monitoring mode and quantified by the external standard method.The calibration curves of 290 pesticide residues were linear in the range of 1.0-200 μg?L-1 with correlation coefficients more than 0.99.The recoveries for all compounds in tea at the fortified levels of 1MRL,2MRL and 4MRL were 67%-119%.The limits of quantitation(LOQs，S/N≥10) for 290 pesticides were less than 10.0 μg?kg-1.The established method was successfully used for the screening and determination of real samples(such as green tea,black tea,oolong tea and pu’er tea) bought at supermarket.The method was simple,rapid and reliable,and could meet the requirement for simultaneous determination of 290 pesticide residues in tea.关键词：high performance liquid chromatography-tandem mass spectrometry;QuEChERS;pesticide residues;tea
- 2868
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- 5
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- 40
发布时间： - 摘要：The interaction mechanisms and structure-activity relationships of lysozyme(LYSO) with psoralen,isopsoralen,5-methoxypsoralen and 8-methoxypsoralen were investigated by ultraviolet spectroscopy,fluorescence spectroscopy,synchronous fluorescence spectroscopy and circular dichroism spectroscopy under the simulative human physiological conditions.The results of ultraviolet difference spectra initially revealed that four furanocoumarin drugs could interact with LYSO.Fluorescence spectra showed that the intrinsic fluorescence of LYSO was significantly quenched by four furanocoumarin drugs and the mechanism of fluorescence quenching was static quenching with non-radiation energy transfer.The 1∶1 complexes were formed between each of the four furanocoumarin drugs and lysozyme.The binding parameters of four furanocoumarin drugs(psoralen,isopsoralen,5-methoxypsoralen and 8-methoxypsoralen) with LYSO at 310 K were as follows:the binding constants(K) were 1.02×104,6.95×104,7.05×104 L?mol-1 and 8.60×104 L?mol-1,and the binding distance(r) were 4.36,4.75,5.25 and 5.89 nm,respectively.The major driving forces were hydrogen bond and Van der Waals.The different positions of furan ring and methoxy led to the different interactions of four furanocoumarins drugs and lysozyme,and the order of the interaction strengths between each of four furanocoumarin drugs and lysozyme were as follows:8-methoxypsoralen＞5-methoxypsoralen＞isopsoralen＞psoralen.The results of circular dichroism indicated that four furanocoumarin drugs had impacts on the secondary structure of LYSO.Psoralen,isopsoralen,5-methoxypsoralen and 8-methoxypsoralen made the content of α-helical structure of LYSO reduce by 27.1%,11.5%,10.6% and 0.917%,respectively.The results of synchronous fluorescence spectra demonstrated that psoralen,5-methoxypsoralen and 8-methoxypsoralen could combine with LYSO and had effects on the conformation of LYSO,while isopsoralen had a less effect on the conformation of LYSO than the other three furanocoumarin drugs.关键词：furanocoumarin drugs;lysozyme;spectroscopy;mechanism of fluorescence quenching;structure-activity relationship
- 2621
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- 1648
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- 3
发布时间： - 摘要：A new method was developed for the determination of aniline and benzidine in environmental water by direct injection and ultrahigh-pressure liquid chromatography(UPLC) with fluorescence detection.Through the investigation of mobile phase,pH value and conductivity of water samples,and filter materials,the optimum conditions were obtained.Under the optimal conditions,water samples were filtered through the microfiltration membrane(0.22 μm，PTFE),and analyzed by UPLC using acetonitrile-3.85 g/L ammonium acetate(25∶75) as mobile phase in 0.8 min.The fluorescence detection wavelengths were set at λex/λem=232 nm/329 nm for aniline and λex/λem=292 nm/383 nm for benzidine.Good linear relationships were obtained in the range of 1.0-100.0 μg/L for aniline and benzidine with correlation coefficients more than 0.999.The relative standard deviations(n=10) of 10.0 μg/L aniline and benzidine were 0.4% and 0.5%,respectively.Recoveries for the method were in the range of 86%-106%.The detection limits(S/N=3) for aniline and benzidine were 0.023 μg/L and 0.024 μg/L,and the quantitation limits(S/N=10) were 0.078 μg/L and 0.079 μg/L,respectively.The method was simple,sensitive and rapid,and could be applied in the detection of aniline and benzidine in environmental water.关键词：Ultrahigh-pressure liquid chromatography;aniline;benzidine;fluorescence detection;direct injection
- 2734
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- 1949
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- 19
发布时间： - 摘要：The electrochemical copolymerization of diphenylamine(DPA) and o-aminophenol(OAP) was studied by using in situ ultraviolet-visible(UV-Vis) spectroelectrochemical and cyclic voltammetric techniques.The different voltammetric characteristics between the homopolymerization and copolymerization processes exhibited the occurrence of the copolymerization of DPA and OAP in 4 mol/L H2SO4.The in situ UV-Vis spectra showed that,during the copolymerization of DPA and OAP,DPA and OAP were firstly oxidized to generate their cation radicals，then a mixed oligomer intermediate was formed by the cross-reaction of the cation radicals of DPA and OAP with the DPA and OAP monomers or their cation radicals in solution,and the absorption peak located at 508 nm was assigned to this intermediate.Further studies showed the difference was existed between the copolymerization of DPA and OAP with different concentration ratios,indicating the dependence of the copolymerization on the concentrations of DPA and OAP.关键词：o-aminophenol;diphenylamine;copolymerization;in situ UV-Vis spectroelectrochemistry
- 2895
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- 1538
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- 0
发布时间： - 摘要：Molecularly imprinted polymers（MIPs) were synthesized by bulk polymerization using polydatin（POL) as template molecule,acrylamide（AM),4-vinylpyridine(4-VP),2-hydroxyethylmetacrylate(HEMA) or methacrylic acid（MAA) as functional monomer,and ethyleneglycol dimethacrylate（EGDMA) as crosslinking agent,initiating thermally with azobisisobutyronitrile（AIBN).The binding and selectivity of MIPs to POL and different substrates were evaluated by the static batch method.MIP1,which was synthesized with AM as functional monomer,had the best recoginition property to the template,followed by MIP2 sythesized with 4-VP as functional monomer,MIP3 synthesized with HEMA as functional monomer and MIP4 synthesized with MAA as functional monomer.The results indciated that the interactions between the template and the functional monomer in the solvent influenced the recognition property of MIPs．Static equilibrium binding experiments and the scatchard analysis showed that MIP1 existed good selectivity and recognition properties to the template POL.Two kinds of binding sites were produced in the MIP1 matrix and their dissociation constants were calculated to be 7.43×10-5 mol/L and 3.70×10-3 mol/L,respectively.Compared with non-imprinted polymer(NIP1),the imprinted polymer(MIP1) exhibits a higher affinity for POL among the mixed substrates.The MIP1 was applied in the specific extraction of POL from Polygonum cuspidatum Sieb.et Zucc.extracts with satisfactory results.关键词：molecularly imprinted polymers(MIPs);polydatin;recognition property;polygonum cuspidatum Sieb.et Zucc.extracts;solid phase extraction
- 3477
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- 2141
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- 5
发布时间： - 摘要：The hydrolysis process of pentaerythritol diacetals，including influence of reaction rate under different reaction conditions and different substituted groups on the aromatic ring of the reaction substrates，was studied with 1H NMR spectra.With pentaerythritol diacetals as the starting materials，their hydrolysis process was detected in the NMR tube under acidic conditions.The experimental results showed that the hydrolysis rate of pentaerythritol diacetals was increased with the rising of reaction temperature or the acidity of the reaction condition.The electron-donated groups on the aromatic ring of the reaction substrates could accelerate the hydrolysis;However，the electron-withdrawn groups could decelerate the reaction.The reaction rate sequence with the same electron-donated groups on the aromatic ring of the reaction substrates is：para-position＞ortho-position＞meta-position,and the reaction rate sequence with the same electron withdrawn groups on the aromatic ring of the reaction substrates is：meta-position＞para-position＞ortho-position. Therefore，a new method for on-line tracking of the hydrolysis of pentaerythritol diacetals was established.This method has the advantages of speediness and repeatability.The results could provide a theoretical reference for the hydrolysis of pentaerythritol diacetals.关键词：pentaerythritol diacetals;1H NMR;on-line tracking;hydrolysis rate
- 2840
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- 1696
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- 0
发布时间： - 摘要：A GC-MS method was developed and validated for the determination of sixteen polycyclic aromatic hydrocarbons(PAHs) listed by the US Environmental Protection Agency as priority pollutants in marine organisms such as fish,shrimp,mussel,crab and the others.The procedures of extraction and purification,as well as chromatographic and mass spectrometric parameters,were optimized.The biological samples were extracted ultrasonically with hexane-dichloromethane(2∶1) mixture,and treated with 60% sulfuric acid,followed by clean-up with a glass column containing Florisil and neutral alumina.The analysis of target compounds was performed by gas chromatography-mass spectrometry(GC-MS).Under the optimized conditions,the calibration curves of 16 PAHs were linear in the range of 0.005-0.500 mg/L with correlation coefficients(r) not less than 0.998 4 and limits of detection of 0.03-0.28 μg/kg.The average spiked recoveries for the fishery products at the spiked levels of 2,20 and 100 μg/kg were in the range of 55%-118%,80%-114% and 79%-113%,respectively,with relative standard deviations(RSDs,n=6) less than 10%.The results showed that the method is rapid,accurate,sensitive and reliable,and could satisfy the requirements for analysis on persistent organic pollutants(POPs) in marine organisms.关键词：ultrasonic extraction;gas chromatography-mass spectrometry;polycyclic aromatic hydrocarbons;marine organisms
- 2824
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- 1772
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- 14
发布时间： - 摘要：An ultra performance liquid chromatography-tandem mass spectrometric(UPLC-MS/MS) method was developed for the simultaneous determination of triclosan and triclocarban in daily chemical products,including toothpaste,hand sanitizer,disinfectant,shampoo and soap.The samples were ultrasonically extracted with organic solvents and centrifugated.The analytes were separated on an ACQUITY UPLC HSS T3 column,and identified under negative electrospray ionization(ESI-) and multiple reaction monitoring(MRM) mode.The standard calibration curves were used for the quantitative analysis.Good linearities were achieved for triclosan and triclocarban over the ranges of 1-250 μg/L and 0.2-50 μg/L,respectively,with correlation coefficients(r2) more than 0.995.The quantitation limits of the method were in the ranges of 0.2-0.7 mg/kg for triclosan and 0.01-0.02 mg/kg for triclocarban.Mean recoveries of the two target compounds in five kinds of daily chemical products at three spiked concentration levels ranged from 86% to 116% with relative standard deviations(RSDs) no more than 15%.This method could be applied in the simultaneous determination of triclosan and triclocarban in daily chemical products.关键词：ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS);triclosan;triclocarban;daily chemical products
- 2710
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- 2048
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- 15
发布时间： - 摘要：A graphene magnetic nanoparticles(G-Fe3O4) was prepared,and used as the adsorbent for the preconcentration of trace amount of copper using 1-(2-pyrrole azo)-2-naphthol(PAN) as chelating reagent prior to its determination by flame atomic absorption spectrometry.This magnetic solid phase extraction method,which takes the advantages of both the high adsorption ability of graphene nanoparticle and the easy phase separation of the magnetic materials from the sample solution,could avoid of the time-consuming experimental procedures in the traditional solid phase extraction,such as centrifugation and filtrations.Various experimental parameters affecting the extraction efficiencies were investigated.Under the optimum conditions,the concentration factor for the analyte was 80.4.The linearity of the method was in the range of 0.5-100 μg/L with a correlation coefficient(r) of 0.998 1.The limit of detection(S/N=3) was 0.067 μg/L.The relative standard deviations(RSDs,n=5) varied from 2.1% to 5.2%,and the spiked recoveries were in the range of 94%-103%.The method was proved to be simple,convenient and sensitive for the determination of trace copper in environmental water samples.关键词：graphene magnetic nanoparticles;flame atomic absorption spectrometry;copper;environmental water samples
- 3112
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- 3
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- 10
发布时间： - 摘要：Based on the sensitization effect of matrine on Ru(bpy)2+3 electrochemiluminescence system,an electrochemiluminescence method for the determination of matrine at silica sol-nano-gold modified gold electrode was established according to the advantages of sol-gel immobilization method and electrocatalysis of gold nanoparticles．The electrochemical and ECL characteristics of matrine at the modified electrode were studied，and the modified electrode exhibits good electrochemical activity and ECL response．Under the optimum conditions，the calibration curve was linear over matrine concentration in the range of 1.5×10-7-1.5×10-4 mol/L(r2=0.998 4),with a detection limit(S/N=3) of 7.3×10-9 mol/L．The RSD(n=8) for determination of 1.5×10-5 mol/L matrine was 1.4% .The spiked recoveries were in the range of 98%-102%,and RSD(n=5) was 1.8%.The proposed method showed high selectivity and sensitivity,and was applied in the analysis of matrine in tablet with satisfactory results.关键词：electrochemiluminescence;Ru(bpy)2+3;silica sol;nano-gold;matrine
- 2700
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- 1666
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- 4
发布时间： - 摘要：An automated online gel chromatography/gas chromatography-mass spectrometry(GPC/GC-MS) method was established for the determination of 11 phenoxy acid herbicide residues in fruits.The sample was extracted with acetone-hexane and derivatived with butanol sulfuric acid,then the extract was purified by Florisil solid phase extraction column and analyzed by automated online GPC/GC-MS under selected ion monitoring(SIM) mode.The results indicated that the calibration curves of 11 pesticides were linear in the range of 0.01-1.0 mg/L ,with correlation coefficients of 0.998 7-0.999 9.The average recoveries of 11 phenoxy acid herbicide in fruits at spiked levels of 0.02-0.10 mg/kg ranged from 66%to 112% with relative standard deviations(RSDs) of 3.4%-11.5%.The method has high sensitivity for 11 phenoxy acid herbicides with quantitation limits of 7-10 μg/kg.The method was simple,rapid,sensitive and effective,and could meet the requirement for the simultanous determination of 11 pesticide residues in fruits.关键词：online GPC/GC-MS;phenoxy acid herbicides;pesticide residues;fruits
- 2665
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- 1873
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- 5
发布时间： - 摘要：A liquid chromatography tandem mass spectrometric method was developed for the determination of benzimidazole fungicides and their metabolites such as thiophanate-methyl(TM),2-aminobenzimidazole(2-AB),carbendazim(MBC),triabendazole(TBZ),5-hydroxy-triabendazole(5-OH-TBZ) in 7 types of concentrated fruit juices including apple,mango,pineapple,pear,orange,lychee and passion fruit.Seven representative concentrated fruit juices were selected and extracted with acetonitrile.The extracts were purified with PSA column.The separation of 5 analytes was carried out on a ZORBAX Eclipse XDB-C18 column using methanol-10 mmol/L ammonium acetate(containing 0.1% formic acid) as mobile phase by gradient elution.The detection of analytes was performed by electrospray tandem mass spectrometry with ES+ and multiple reaction monitoring (MRM) modes.The results showed that,the method showed good linear relationships in the range of 0.02 -0.2 mg/L for the tested samples,with correlation coefficients no less than 0.998 5.The quantitation limits were 2.0 μg/kg for 2-AB and 5-OH-TBZ,and 1.0 μg/kg for the rest of the analytes.The mean recoveries ranged from 70% to 110% with relative standard deviations of 0.1%-10.9% when the fortified levels for 2-AB and 5-OH-TBZ were 2,4,20 μg/kg and those for TBZ，MBC，TM were 1,2,10 μg/kg,respectively.The proposed method was sensitive and reliable,and was successfully applied in the determination of benzimidazole fungicides and their metabolites in real commercial concentrated juices.关键词：liquid chromatography tandem mass spectrometry;concentrated fruit juices;thiophanate-methyl;2-aminobenzimidazole;carbendazim;triabendazole;5-hydroxy-triabendazole
- 3256
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- 1969
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- 10
发布时间： - 摘要：The analysis of pesticides in water samples is a problem of primary concern to quality control laboratories due to the toxicity level of these compounds and their public health risk.A method for the analysis of eight phenoxy acid herbicide residues in water was developed using solid phase extraction(SPE) combined with ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The water samples were extracted and cleaned with HLB SPE column.The extract was separated on a BEH C18 column using acetonitrile-2 mmol/L aqueous ammonium acetate as mobile phase with a linear gradient elution program,and analyzed by MS under negative ion mode with multiple reaction monitoring(MRM) mode.The calibration curves of eight phenoxy acid herbicides were linear in the concentration range of 0.8 -100 μg/L,with correlation coefficients of 0.995 8-0.999 6.The spiked recoveries ranged from 74% to 90%,with relative standard deviations of 1.0%-12.0%.The detection limits(3S) were between 1.0 ng/L and 1.8 ng/L.The method was simple,rapid,sensitive and accurate,and was suitable for the simultaneous determination of eight phenoxy acid herbicides in surface water and waste water.关键词：phenoxy acid herbicides;UPLC-MS/MS;SPE;water
- 3065
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- 1857
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- 4
发布时间： - 摘要：PEG modified Fe3O4 nanoparticles synthesized by coprecipitation were dispersed in sodium dodecylbenzenesulfonate(SDBS) solution and modified on the surface of magnetic carbon paste electrode(MCPE) to prepare the SDBS-PEG-Fe3O4/MCPE.Cyclic voltammetry(CV) showed that the modified electrode exhibited a strong catalytic effect on the electrochemical oxidation of dopamine(DA).The oxidation peak current on the modified electrode was 5 times higher than that on the bare MCPE.The potential difference between oxidation peak and reduction peak decreased from 0221 V to 0.044 V,which indicated the increase of redox reversibility of DA.Square wave voltammetry(SWV) showed that the oxidation peak current had a linear relationship with concentration of DA in the ranges of 5.0×10-7-2.0×10-5 mol/L and 2.0×10-5-1.0×10-4 mol/L.The detection limit(S/N=3) was 1.4×10-7 mol/L.The interference of ascorbic acid(AA) and uric acid(UA) could be eliminated efficiently.The proposed method was used to detect the dopamine hydrochloride injection with satisfactory results.关键词：PEG-Fe3O4;nanoparticles;modified electrode;dopamine
- 3034
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- 1494
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- 0
发布时间： - 摘要：An amphiphilic triblock copolymer poly(lactic-co-glycolic-acid) polyethyleneglycol-A10 aptamer(PLGA-PEG-Apt) was synthesized,and its characteristic peaks were investigated with 1H nuclear magnetic resonance(1H NMR).Nanoparticles gene delivery system was prepared by the water-in-oil-in-water(w1/o/w2)double emulsion solvent evaporation(DESE) method.Nanoparticle size measured by dynamic laser light scattering was (225.2±8.1) nm(Mean±SD,n=3),and zeta potential was (-35.5±-3.3) mV.SEM graphs show that the nanoparticles look round,and have smooth surfaces and uniform size distributions.The TFO encapsulation efficiency and drug loading percentage were (25.4±3.1)%(n=3) and (1.34±0.16) μg/mg,respectively.In vitro drug release study with TFO-NP-Apt,a sustained slow release was observed after an initial burst.A10 aptamer modified nanoparticles could penetrate into targeted LNCaP cells more efficiently,then inhibit the proliferation of cells.In this study,the targeted PLGA nanoparticles for gene delivery were prepared successfully.关键词：poly(lactic-co-glycolic-acid);polyethyleneglycol;aptamer;nanoparticle;gene vector
- 3125
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- 1624
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- 2
发布时间： - 摘要：A hydrophilic interaction chromatography(HILIC) fingerprinting method had been established for the quality evaluation and discrimination of mulberry leaves.The chromatographic fingerprints were determined by injecting 20 μL of the sample solution each time into the hydrophilic interaction chromatography column(XBridgeTM Amide column) with the gradient elution solvent system composed of water(containing 0.2% formic acid,20 mmol/L ammonium formate and 20% methanol) and acetonitrile．The flow rate was 0.8 mL/min,the column temperature was maintained at 25 ℃ and the signals were acquired at 322 nm.The result indicated that the developed HILIC method was simple,accurate and reliable for the development of mulberry leaves fingerprint.The HILIC fingerprints for ten samples tested contained the same seventeen peaks and four characteristic peaks.Combining with the similarity analysis, the method could be used to discriminate different origins of mulberry leaf samples.The HILIC fingerprinting technique is expected to become an important tool in the identification and quality evaluation of mulberry leaves.关键词：mulberry leaves;hydrophilic interaction chromatography;fingerprint
- 2829
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- 1701
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- 2
发布时间： - 摘要：A capillary zone electrophoresis(CZE) method was established for the separation and determination of three effective compounds such as caffeine,theobromine and theophylline in alkaloidal samples.The sample was separated on an uncoated silica capillary(75 μm i.d.×60 cm，effective length:50 cm) using pH 9.0 20 mmol?L-1 borate containing 4 mmol?L-1 beta-cyclodextrin (β-CD) as running buffer.The pressure of injection was set at 0.5 psi and the time was set 5 s.The detection wavelength was 273 nm.A voltage of 16 kV was applied at 25 ℃.Under the optimal conditions,good linear relationships were observed between peak areas and alkaloidal concentrations in the range of 0.036-0.288 g?L-1, with correlation coefficients not less than 0.998 4.The RSDs of the peak area were not more than 3.2%.The limits of detection (LODs) were not more than 2.7 mg?L-1.The average recoveries were in the range of 97%-104%.This method is simple,quick and less reagent-consuming,and is suitable for the separation and determination of the three alkaloids in real samples.关键词：capillary zone electrophoresis;effective compounds;caffeine;theobromine;theophylline
- 2571
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- 1682
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- 0
发布时间： - 摘要：A method for the determination of three antibiotic drugs,including chloramphenicol(CAP),thiamphenicol(TAP) and florfenicol(FF) in feed was developed using high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).The target analytes were extracted with basic ethylacetate,and evaporated to dryness.The extracts were defatted with hexane and cleaned up by liquid-liquid partition.Three analytes were detected with electrospray ionization(ESI) in negative mode using multiple reaction monitoring,and quantified by the internal standard method.Under the optimal conditions,the calibration curves of chloramphenicol,florfenicol and thiamphenicol were linear in the ranges of 0.2-10.0,0.2-10.0 μg/L and 1.0-50.0 μg/L,respectively,with correlation coefficients not less than 0.990 0.The limits of detection(LODs) were 0.1，0.1,0.5 μg/kg, and the limits of quantitation(LOQs) were 0.3,0.3,1.5 μg/kg,respectively.The average recoveries ranged from 77% to 108% with RSDs not more than 10.9%.关键词：high performance liquid chromatography-tandem mass spectrometry;feed;chloramphenicol;thiamphenicol;florfenicol
- 3210
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- 1987
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- 6
发布时间： - 摘要：A rapid method for the determination of geniposide,gentiopicroside and baicalin in Longdanxiegan Pill was established.The sample was extracted with 50% methanol,and then purified with C18 solid phase extraction.The extract was separated on an Ultimate XB-C18 (4.6 mm×50 mm,1.8 μm) column at 25 ℃,using acetonitrile-0.1% phosphate acid as mobile phase by gradient elution at flow rate of 0.8 mL?min-1.The effects of experimental conditions,such as different type of column,composition of mobile phase,injection volume,column temperature and flow rate,on separation efficiency of three compounds were investigated,and the equilibrium volume of SPE elution was also discussed.Under the optimal conditions,the method showed good linearity with correlation coefficients not less than 0.999 8.The quantitation limits(LOQs) were in the range of 0.24-0.44 mg/L,and the recoveries ranged from 95% to 99% with RSD no more than 2.8%.The method was rapid and reliable for the quantitation of three compounds in Longdanxiegan Pills.关键词：Longdanxiegan Pill;SPE;HPLC;geniposide;gentiopicroside;baicalin
- 2761
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- 1782
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- 9
发布时间： - 摘要：The application of a pretreatment instrument,SPD-600,in dioxin-like substances determination by a new enzyme-linked immunosorbent assay method was introduced in this paper,Its clean-up efficiencies and recoveries under different conditions were evaluated.The results indicated that SPD-600 achieved the optimum performance under a heated condition of 60 ℃ when almost all impurities were removed.And the recoveries of the labeled internal standards are comparable with that of the multilayer silica column treatment.In addition,an ELISA-based kinetic exclusion assay method using an automatic analysis instrument(DXS-600) was developed for dioxin analysis,which had avoided the competitive step.The results showed that DXS-600 eliminated the artificial effects and was more sensitive and stable than the traditional ELISA.Finally,21 flue gas samples were determined using SPD-600 combined with DXS-600 systems,and the results obtained were compared with those of the HRGC-HRMS analysis.A good correlation with r2 of 0.985 8 was found between two methods.Therefore,the method of SPD-600 clean-up combined with DXS-600 analysis can be used as a quick screening method for the determination of dioxin.关键词：SPD-600;DXS-600;high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS);dioxin
- 3069
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- 1927
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- 4
发布时间： - 摘要：A comprehensive analytical method based on liquid chromatography-tandem mass spectrometry was developed for the determination of α,β,γ-hexabromocyclododecane in polymer food contact materials.The samples were ultrasonically extracted with acetone as extraction solvent.The extract was cleaned up with ENVI-Carb Ⅱ/PSA solid phase extraction cartridge.The separation of the analyte was performed on a Waters XBridge C18 (150 mm×2.1 mm,3.5 μm) column using methanol-acetonitrile-water(41∶41∶18) as mobile phase by isobaric elution.The qualitative and quantitative analysis of the analyte were carried out under the multiple reaction monitoring(MRM) mode.The limits of quantitation(LOQs) for α,β,γ-hexabromocyclododecane were all 40 μg/kg.The mean recoveries at three spiked levels of 40.0-160.0 μg/kg were in the range of 86%-91%,with relative standard deviations(RSDs) of 1.9%-4.7%.The method was accurate,rapid and sensitive and was applicable to the inspection of hexabromocyclododecane in food contact materials.关键词：food contact materials;hexabromocyclododecane;liquid chromatography tandem mass spectrometry
- 3554
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- 1792
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发布时间： - 摘要：An ultra performance liquid chromatographic(UPLC) method was developed for the determination of thiacloprid，flubendiamide and their metabolite residues in paddy soil and water.The paddy water was extracted with ethyl acetate,and the organic phase was concentrated to constant.The paddy soil was extracted with acetone-water and the extract was purified by liquid-liquid distribution.The optimization chromatographic conditions were as the follows：separation column：ACQUITY UPLC HSS T3 chromatographic column(2.1 mm×100 mm，1.8 μm)，mobile phase：acetonitrile-water，flow rate：0.3 mL?min-1，column temperature：35 ℃，sample volume：5 μL，detection wavelength：230 nm.Under the optimized conditions，the calibration curves of thiacloprid，flubendiamide and their metabolite residues showed good linearities in the range of 0.01-10.00 mg?L-1 with correlation coefficients of 1.000，1.000，0.999 9,respectively.The instrumental detection limits of three compounds were in the range of 0.001-0.002 mg?L-1，and their method detection limits were 0.000 4-0.001 0 mg?L-1 for water sample and 0.002 2-0.003 6 mg?kg-1 for soil sample.The spiked recoveries were in the range of 82%-106% with RSDs(n=5) of 0.81%-3.8%.With the advantages of easy operation，good separation effect，high sensitivity and accuracy，the proposed method was successfully applied in the determination of thiacloprid，flubendiamide and their metabolites in real samples.关键词：thiacloprid;flubendiamide;paddy soil;paddy water;ultra performance liquid chromatography(UPLC);residue
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