最新刊期
卷 36 ， 期 2 ， 2017
- 摘要：Ambient mass spectrometry has been increasingly applied in tissue sample analysis with the advantages of high sensitivity,high speed and the capability for providing molecular structure information of compounds in complex matrices.Traditionally,the time-consuming sample pretreatment procedures including homogenization,extraction and separation are inevitable for tissue sample analysis,and commonly associated with biological degradation,chemicals contamination and bioactive components loss in sample preparations.Recently,with the development of novel ambient mass spectrometry techniques,in situ tissue samples analysis has become possible without sample pretreatment. The applications of ambient mass spectrometry in tissue samples analysis are mainly discussed in this review,and their impacts in different fields, such as life science,clinical medicine,food science and in vivo analysis are prospected.关键词：mass spectrometry;tissue sample;applications;review
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发布时间： - 摘要：Mass spectrometry(MS) is one of the most important analytical technologies for metabolomics.In recent years,metabolomics based on MS has been widely used in disease diagnosis,drug effect research,nutrition,toxicology,sports medicine,etc.This paper reviews the sample pretreatment,analytical tools,data processing method and main application fields in the past five years.The development tendency of metabolomics in future is also proposed.关键词：mass spectrometry(MS);metabolomics;advance;review
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发布时间： - 摘要：Lipidomics,firstly proposed in 2003,is an emerging field, where the structures, functions and dynamic changes of lipids in cells,tissues or body fluids are investigated.Studies have showed that the disturbance of lipid metabolism is closely related to some diseases,such as cancer,atherosclerosis,diabetes,obesity and Alzheimer disease.Therefore, the comprehensive analysis of lipid becomes significant. However, due to the diversity and complexity of lipids,lipids analysis is still full of challenges.Recently,Matrix-assisted laser desorption and ionization mass spectrometry imaging(MALDI MSI) has been developed quickly in lipidomics research. Compared with traditional LC-MS,MALDI MSI provides spatially resolved ion intensity maps corresponding to the mass-to-charge ratio of intact molecular species at specific locations in a prepared tissue sample, which is very useful in biomarker identification analysis,drug distribution analysis,etc. MALDI MSI is a relatively new technique,it still has many aspects needing further improved,such as small molecules detection, neutral lipids detection,ion suppression elimination,detection sensitivity improvement,etc.In MALDI MSI analysis,sample preparation,new matrix development and application research are the three hotspots.This review aims to introduce the research progress of MALDI MSI in sample processing,matrix coating and its application.The existing problems and possible solutions are discussed,in order to extend the application of MALDI MSI.关键词：matrix-assisted laser desorption/ionization mass spectrum imaging(MALDI MSI);lipidomics;sample preparation;matrix;marker;review
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发布时间： - 摘要：Key parameters of air flow assisted ionization mass spectrometry imaging（AFAI-MSI） system were investigated and optimized by using tissue sections adding homogeneous NHBA as the target samples.The parameters，including those related with spray solvent，spray gas，as well as geometric setting of AFAI system were optimized. Based on the optimization，stability of endogenous metabolites from the tissue section was also taken into consideration during the AFAI-MSI experiment.It usually takes 7-8 h for a complete MSI experiment for a whole-body tissue section，and the stability of endogenous metabolites needs to be investigated during such a long process. Therefore，a whole-body tissue section was imaged twice consecutively，and then the data of resulted images were compared using visualized component principle analysis（PCA） after selecting main mass spectra peaks.By visualized comparing of the result，the similarity of the visualized PCA score plot demonstrated the endogenous metabolites were stable during MSI experiment.In conclusion，the optimized parameters guaranteed the stability and sensitivity of AFAI-MSI experiment.Additionally，after proper sample pretreatment，the endogenous metabolites in tissue sections were able to remain stable during the AFAI-MSI experiment，which ensured the reliability for research of the variability of endogenous metabolites.Thus the AFAI-MSI method is promising to be applied in the study of drug development.关键词：airflow assisted ionization（AFAI）;ambient mass spectrometry imaging（AMSI）;sample stability;medicines;endogenous metabolites
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发布时间： - 摘要：Analyses of cell and cell metabolites are important in biological systems. Microfluidic technology is a powerful tool for their studies.In this paper，the recent advances of microfluidic technology,especially its combination with mass spectrometry in cell analysis and cell metabolite’s assay，are summarized.Some insights for researchers interested in developing novel，robust microfluidic platforms for cell-biology research，are provided.关键词：microfluidic chip;mass spectrometry;cell analysis;cell metabolite assay
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发布时间： - 摘要：Peptides play an important role in life process.In this paper,two endogenous neuropeptides including methionine enkephalin and leucine enkephalin were selected as research targets.They were synthesized by Fmoc solid phase peptide synthesis strategy.An HPLC-ESI-MS/MS method was established to investigate the composition of synthetic peptides.The possible structure modifications during peptide synthesis procedures were also identified.The results showed that the main byproducts were incomplete peptides and oxidative peptides.Solutions for high efficient synthesis of methionine enkephalin and leucine encephalin were further proposed.This study provides new perspectives in rapid peptide structure identification and efficient bioactive peptide synthesis.关键词：solid phase peptide synthesis;methionine enkephalin;leucine enkephalin;oxidation;high performance liquid chromatography tandem mass spectrometry(LC-MS/MS)
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发布时间： - 摘要：Intermolecular noncovalent interaction is very important for understanding structures and properties of molecular complexes and clusters.Electrospray ionization mass spectrometry（ESI-MS） has demonstrated its powerful utility in the detection and research of weakly bound complex ions,including amino acids,peptides and proteins.In this paper,the noncovalent complex ions of arginine and tryptophan with phosphoric acid were investigated by ESI-MS method.The experiments were performed on a Fourier transform ion cyclotron resonance(FT ICR) mass spectrometer. The results showed that for both systems,wide varieties of noncovalent complex ions were generated and detected in the mass spectra.Most of these complex cations are singly or doubly charged,including both units of amino acid and phosphoric acid.The differences among different systems are also reflected by the distributions of the formed complex ions.关键词：noncovalent complex;electrospray ionization(ESI);arginine;tryptophan;phosphoric acid
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发布时间： - 摘要：With their targeting abilities，small sid-effects and low toxicity,antibody drugs could be directly combined with target specific，and they have broad application prospects in clinical practice.With its rapidness，high sensitivity and resolution，mass spectrometry(MS) has become an important means to analyze the structure of antibody，which provides a strong technical support for quality control and safety of the drug.In this paper，the rapid application development of organic mass spectrometry in the consistency of the amino acid sequence of antibody class，advanced structure and post translational modification（PTMs） are reviewed .关键词：organic mass spectrometry;antibody;structural analysis;review
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发布时间： - 摘要：The fragmentation behaviors of quercetin and morin were analyzed and compared by the quantum chemistry method with electrospray ionization mass spectrometry（ESI-MS） in negative ion mode.Based on the density functional theory（DFT），at the level of B3LYP/6-31G（d），quantum chemistry calculation was carried out to optimize the molecular spatial configurations of quercetin and morin，in order to confirm the stable geometric configurations and deprotonation locations of quasi-molecular ions.The energy of fragment ions on the stable state under the relative framentation voltage in the second order mass spectrometry，was calculated at the level of RB3LYP/6-31+G（2d,2p）.The fragmentation pathway was deduced by comparing the stable configurations of quasi-molecular ions and combined with basis set superposition error（BSSE）-corrected bond dissociation energy（BDE）.The results indicated that the stable configuration of quercetin was that the A，B，C rings stayed in the same plane，but morin was not like this because of the 2′-OH，and the dihedral angle between B ring and AC rings was-134.662 4°.The fragmentation processes of quercetin and morin occurred mainly through the cross-ring cleavages of C ring with various of cleavage ways.The precedence order was：1,2 cleavage，0,2 cleavage，1,3 cleavage，1,4 cleavage and 0,4 cleavage，the fragment ions of 1,2A-，0,2A-，1,3A-，1,4A- and 0,4A- were generated，respectively.The difference between them was that the existence of 2′-OH on morin facilitated the cross ring cleavages.Subsequently，the rest of fragment ions were produced step by step.This study provided a theoretical basis for further revealing the fragmentation pathway of flavonol compounds.关键词：flavonol;quantum chemistry;electrospray ionization mass spectrometry（ESI-MS）;fragmentation behavior
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发布时间： - 摘要：A flow rate/organic solvent double-gradient mode in reversed phase high performance liquid chromatography(HPLC) by using monolithic column was established as a new approach for the rapid and simultaneous determination of notoginsenoide R1,ginsenosides Rg1,Re,Rb1,Rd,Rb2 and tanshinone ⅡA in compound Salvia miltiorrhiza bunge tablets.Through the optimization of the flow rate/organic solvent double-gradient mode,and combination with chromatographic simulation software DryLab,the optimized double-gradient HPLC system for the seven active components was built.The determination was carried out on a Merck Chromolith Performance RP-18e(100 mm×4.6 mm) column using acetonitrile-water as mobile phase at a column temperature of 30 ℃.The separation of seven active components in the tablets was achieved in 21 min.The linear ranges were 60.60-242.40 mg/L(r=0.999 0) for Rg1,16.52-66.08 mg/L(r=0.999 9) for tanshinone ⅡA，and 30.70-142.66 mg/L(r≥0.999 4) for the other active components.The LOQs( S/N=10) were in the range of 21-124 μg/kg and the mean recoveries were 96.7%-100.1%.The method could be used for the simultaneous determination of different polarity compounds in a short time.It also could improve the column efficiency of the analytes,compress the half-peak width and reduce the trailing.Therefore,the method could be used for the rapid and simultaneous determination of the seven active components in compound Salvia miltiorrhiza bunge tablets.关键词：flow rate/organic solvent double-gradient;monolithic column;high performance liquid chromatography(HPLC);compound Salvia miltiorrhiza bunge tablets;DryLab
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发布时间： - 摘要：A confirmative method was developed for the simultaneous determination of 46 antibiotics,including sulfonamides，quinolones and macrolides in organic fertilizer by ultrahigh performance liquid chromatography-tandem massspectrometry(UPLC-MS/MS).The samples were extracted with acetonitrile-EDTA buffer solution(pH 10.0),and separated by centrifugation after salting out.The upper acetonitrile layer was purified by the QuEChERS steps with sorbents.The buffer solution layer was purified with solid-phase extraction cartridge.The separation of target drugs was performed on an ACQUITY UPLC BEH C18column using a mobile phase consisting of 2 mmol/L ammonium acetate with 0.1% formic acid and methanol by gradient elution．The analysis of target compounds was carried out with positive electrospray ionization(ESI+)source under multiple reaction monitoring(MRM) mode.The matrix-matched external standard calibration was used for quantification.Good linearities for the 46 antibiotics were achieved over the concentration of 1-200 μg/L,with correlation coefficients(r2) of 0.996 6-0.999 9.The recoveries of sulfonamides,quinolones and macrolides at spiked levels of 25，100,400 μg/kg were in the range of 67.8%-95.6%,65.6%-89.4% and 66.6%-107.8%,respectively,with relative standard deviations(RSDs) of 0.4%-11.9%.The limits of detection(LOD,S/N=3) were 0.6-4.6 μg/kg,and the limits of quantitation(LOQ,S/N=10) were 2.1-15.4 μg/kg.关键词：ultrahigh performance liquid chromatography-tandem massspectrometry(UPLC-MS/MS);antibiotics residues;organic fertilizer;QuEChERS combined with column purification
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发布时间： - 摘要：A new descriptor of amino acids,SVREW, was derived from principal components analysis of 41 randic molecular profiles descriptors，44 eigenvalue-based indices descriptors and the matrix of 47 walk and path counts descriptors of amino acids.The structures of angiotensin-converting enzyme（ACE） inhibiting dipeptides and tripeptides，bitter tasting thresholds dipeptides and tetrapeptides，oxytocin，HLA-A*0201 restricted CTL epitope were characterized with SVREW，using multiple linear regression（MLR） to establish a quantitative structure-activity relationship，at the same time，adopting the methods of internal and external for dual verification of the stability of the model.The relevant statistical parameters were as follows：the correlation coefficient（R2cum），leava one out（LOO） cross-validation correlation coefficient（R2cv） and external validation correlation coefficient（Q2ext） were 0.994，0.797，0.948 for ACE inhibition dipeptides model；0.896,0.686,0.720 for ACE inhibition tripeptides models,0.955,0.859,0.879 for BTT dipeptides model,0.958,0.796,0.843 for BTT tetrapeptides model,0.990,0.954,0.890 for oxytocin model,0.950，0.748，0.773 for HLA-A* 0201 restricted CTL epitope model,respectively.Studies showed that the MLR models constructed by SVREW descriptor had good fitting and predictive abilities,which was an effective structure characterization method in peptide drugs QSAR study and provided a guidance for new drug discovery and research.关键词：quantitative structure-activity relationship;amino acid descriptor;multiple linear regression;peptides
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发布时间： - 摘要：The chloromethyl styrene divinylbenzene copolymer(VBC-DVB) was synthesized by the precipitation polymerization.The strong anion-exchange resin(SAX) containing quaternary ammonium group was then functionalized with trimethylamine.The resulting resins were characterized in the form of monodisperse microspheres,with mean diameters of(3.8±1.5) μm.The resin possessed a high ion exchange capacity(0.83 meq/g) and a good adsorption performance in selectivity,and its saturated adsorption capacities for five quinolone drugs(norfloxacin,ciprofloxacin,lomefloxacin,gatifloxacin,sparfloxacin) were higher than those of conventional commercially available Oasis MAX SPE sorbents.The resin was used for the selective extraction and HPLC analysis of five quinolone drugs in honey samples.The method showed a good linear relationship in the certain concentration with correlation coefficients(r2) not less than 0.998 9.The average spiked recoveries were between 86.8%and 120.3%.The RSDs of intra-day and inter day were not more than 7.0%and 8.5%,respectively.The results mentioned above indicated that the SAX material prepared was suitable for the efficient pretreatment of quinolone drug residues in complex matrices.关键词：strong anion-exchange;trimethylamine modification;solid-phase extraction;honey;quinolone drugs;HPLC analysis
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发布时间： - 摘要：A new magnetic molecularly imprinted polymers(MIPs) were prepared by using Fe3O4@SiO2 as the support,4-vinyl pyridine(4-VP) as functional monomer,bisphenol A(BPA) as template molecule through surface molecularly imprinted polymerization technology.The structure and morphology of Fe3O4@SiO2-MIPs were characterized by infrared spectroscopy(IR)and transmission electron microscopy(TEM).A new method was established for the separation and enrichment of BPA in milk sample by molecularly imprinted magnetic solid-phase extraction combined with high performance liquid chromatography(HPLC) using Fe3O4@SiO2-MIPs as magnetic adsorbent.The results showed that the Fe3O4@SiO2-MIPs has a high selectivity for BPA under the optimized experimental condition,and the adsorption capacity of Fe3O4@SiO2-MIPs was 13.50 mg/g.The calibration curve of BPA was linear in the range of 0.05-5.0 mmol/L with a correlation coefficient(r2) of 0.993 4.The limit of detection(LOD) was as low as 0.037 μg/L.The proposed method was successfully applied in the determination of BPA in milk sample,with average recoveries of 86.2%-93.1%and relative standard deviations(RSDs) of 2.9%-3.8%at three spiked levels.The developed method is rapid and selective,and is adaptable to the analysis of trace BPA in milk sample.关键词：molecular imprinted polymers;magnetic solid-phase extraction;bisphenol A;high performance liquid chromatography(HPLC)
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发布时间： - 摘要：An HPLC method was established for the chiral separation of cinacalcet raw material,1-(1-naphthyl)-ethylamine(compound-1) and intermediate of cinacalcet(compound 2),by using self made 1 naphthalene vancomycin as chiral stationary phase(Na-VAN CSP),and D-tartaric acid(D-Tar)，L-tartaric acid diethyl ester(L-TADE) and D-tartaric acid diethyl ester(D-TADE) as chiral mobile phase additives(CMPA),respectively.The influences of alcohol modifiers and CMPA types were studied.The mechanism of enantioseparation was also discussed.On Na-VAN CSP,compound 1 and 2 got certain degree of enantioseparation with different CMPA under normal phase conditions.When D-TADE was used as CMPA,the optimal enantioseparation for both compound 1 and 2 was obtained.The results showed that the size of alcohol modifier and the three dimensional configuration of CMPA played an important role in the enantioseparation.关键词：1-(1-naphthyl) ethylamine;intermediate of cinacalcet;1-naphthalene vancomycin;chiral mobile phase additive;enantioseparation
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发布时间： - 摘要：A moderate and simple in-situ growth approach was adpoted to bond coppernanoparticles noncovalently to graphene for preparation of CuNPs/PAA/GR nanocomposites which were used for electrocatalysis of ractopamine（RAC）.The morphology of the material was observed by scanning electron microscopy（SEM）,and the state of the modified glassy carbon electrode was investigated by electrochemical impedance（EIS）.Tests at various scan rates and pH conditions indicated that the modified electrode has an adsorption-controlled electrochemical system.The mechanism for the electrode reaction for ractopamine involves a two-electron transter process accompanied by a deprotonation step.Electrochemical parameters were calculated as follows:the electron transfer number（n） was 1.7,the effective area for the CuNPs/PAA/GR/GCE electrode was 3.57 cm2,12.6 times as large as bare electrode,and the adsorption capacity（Гs） value was 1.98×10-12 mol/cm2.Under the optimal conditions by differential pulse voltammetric measurement,the calibration curve of RAC was linear in the range of 1-30 μmol/L（r2=0.990 2） with a detection limit（S/N=3） of 18.3 nmol/L.With advantages of facile fabrication,high sensitivity,good stability and high reproducibility,the sensor was applied in the detection of ractopamine in pork samples with recoveries of 97.0%-102.5% and relative standard deviations（RSD） of 2.8%-3.2%.关键词：graphene（GR）;ractopamine（RAC）;copper nanoparticles（CuNPs）;chronocoulometry;differential pulse voltammetry（DPV）
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发布时间： - 摘要：A GC-MS method was established for the determination of 9 polychlorinated naphthalenes(PCNs),including 1-chloronaphthalene,2-chloronaphthalene,1,4-dichloronaphthalene,1,2,3,4-tetrachloronaphthalene,1,3,5,7-tetrachloronaphthalene,1,2,3,5,7-pentachloronaphthalene,1,2,3,5,6,7-hexahydropyrrolizinium,1,2,3,4,5,6,7-heptachloronaphthalene and octachloronaphthalene in groundwater.Comparative study was conducted between the liquid-liquid extraction(LLE) and solid phase extraction(SPE) for extraction of 9 PCNs in groundwater,and LLE was selected as sample preparing method as it has higher extraction efficiency than SPE.The calibration curves of 9 PCNs were linear in the range of 5-100 μg/L with correlation coefficients(r) more than 0.995.The spiked recoveries for groundwater samples ranged from 70.7% to 112% with relative standard deviations(RSD，n=5) less than 9.9%,and the method detection limits(S/N=3) were in the range of 4.21-7.41 ng/L.The method was accurate and sensitive,and was successfully applied in the determination of 9 PCNs in real groundwater sample.关键词：polychlorinated naphthalenes(PCNs);gas chromatography-mass spectrometry(GC-MS);liquid-liquid extraction(LLE);groundwater
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发布时间： - 摘要：A method of 1H qNMR was developed for the determination of sildenafil citrate，tadalafil and vardenafil added in dietary supplements illegally.In this experiment，Bruker Avance DRX 500 was applied，with deuterated dimethylsulfoxide（DMSO-d6） as solvent and 2,3,5-triiodobenzoic acid as internal standard substance.The spectral width，center frequency，pulse width，relaxation delay and the number of scans were optimized，and the method was validated.The results showed that,the correlation coefficients for the linear regression were not less than 0.999.The detection limits of the method for sildenafil citrate，tadalafil and vardenafil were 0.045，0.026，0.033 mg/mL，and the quantitation limits were 0.218，0.128，0.159 mg/mL，respectively.The inter-day RSDs were 0.38%，0.85%，0.34%，and the intra-day RSDs were 0.72%，1.2%，1.4%，respectively.The accuracy of the method was also verified by comparing the results of 1H qNMR and HPLC-DAD，testing the same 13 samples.The results showed that the RSDs of two methods were between 1% and 8%.关键词：1H qNMR;dietary supplements;sildenafil citrate;tadalafil;vardenafil
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发布时间： - 摘要：A high performance liquid chromatography-quadrupole ion mass spectrometric（HPLC-QTRAP-MS/MS） method was developed for the determination of N-Methyl-o-phenylenediamine residues in telmisartan.After extracted with water-acetonitrile（80∶20，by volume），the telmisartan samples were separated on an Agilent Eclipse XDB-C18 column（3.5 μm,2.1 mm×100 mm） with a mobile phase of 0.1% formic acid solution-acetonitrile.The electrospray was operated in the positive mode and the samples were monitored under the select reaction monitoring（SRM） mode.As a result，the calibration curves of N-Methyl-o-phenylenediamine showed a good linearity（r>0.99） in the range of 2.0-50 μg/L.The limits of detection（S/N=3） was 0.5 μg/L ，and the limits of quantitation（S/N=10） was 2.0 μg/L.The method has the advantages of simple operation，high sensitivity，good reproducibility，and could be used for the detection of N-Methyl-o-phenylenediamine residues in telmisartan.关键词：high performance liquid chromatography-quadrupole ion mass spectrometry（HPLC-QTRAP-MS/MS）;N-methyl-o-phenylenediamine;telmisartan
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发布时间： - 摘要：A high performance liquid chromatographic(HPLC) method was developed for the determination of 5 resin acids,including abietic acid,neoabietic acid,dehydroabietic acid,palustric acid and levopimaric acid in food contact adhesives．The conditions of sample pretreatment and chromatographic separation were optimized.The sample was dissolved with ethyl acetate,and the polymer was precipitated with methanol.After filtration with filter membrane,the extract was separated on a Venusil MP C18(2) column with acetonitrile-0.4%acetic acid(80∶20) as mobile phase at a flow rate of 1.0 mL/min,detected accurately by HPLC with diode-array detector(DAD) at 240 nm for abietic acid and neoabietic acid,270 nm for palustricacid and levopimaric acid,208 nm for dehydroabietic acid,and quantified by the external standard method．The HPLC method showed a good linearity above two orders of magnitude，with detection limits of 2.5-10.0 mg/kg.The RSDs for 5 resin acids were no more than 3.4%,and the recoveries were in the range of 92.2%-103.6%．The method has the advantages of simple operation,rapid analysis and less interference factors,and could provide credible analysis for 5 resin acidsin food contact adhesives.关键词：food package;adhesive;resin acids;high performance liquid chromatography(HPLC)
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发布时间： - 摘要：A modified QuEChERS sample pretreatment method was established for the determination of tetracycline residues in pork.The new method adopted a novel lipid-removal material(EMR-Lipid) in QuEChERS procedure,and provided fast and effective sample extraction and cleanup of high-fat sample such as pork.The LODs of the method were 5.0 μg/kg.The recoveries of tetracycline,chlortetracycline,doxycycline were in the range of 75.6%-89.4% and the recoveries of oxytetracycline were in the range of 53.4%-61.0%,with RSDs not more than 7.7%.关键词：EMR-Lipid;QuEChERS;tetracyclines;residue detection;high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS)
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发布时间： - 摘要：An original method for the simultaneous determination of bisdemethoxycurcumin，demethoxycurcumin and curcumin in plasma，muscle，liver and kidney of yellow catfish（Pelteobagrus fulvidraco），bluntnose black bream（Megalobrama amblycephala） and grass carp（Ctenopharyngodon idellus） was established by ultra high performance liquid chromatography with ultraviolet detection（UPLC-UV）.The sample was extracted using acetonitrile containing 0.01% acetic acid，and the moisture of sample was removed with anhydrous sodium sulfate，then n-hexane was used for removing fat in sample.After that，the sample prepared was separated on an ACQUIT UPLC BEH C18 column and determined at 428 nm.Good linearities were observed in the range of 0.01-5.00 mg/L，and the correlation coefficients for bisdemethoxycurcumin，demethoxycurcumin and curcumin were 0.998 7，0.999 8 and 0.999 6，respectively.The average recoveries of 3 analytes in fish tissues at the spiked level of 0.025-1.00 mg/kg ranged from 64.7% to 102.2%,with relative standard deviations（RSDs） of 0.69%-10.8%.The detection limits（LODs） and quantitation limits（LOQs） for 3 analytes in fish tissues were all 0.010 mg/kg and 0.025 mg/kg，respectively.The presented method was firstly applied in the investigation on the pharmacokinetic profile of curcumin in bluntnose black bream.关键词：fish tissues;bisdemethoxycurcumin;demethoxycurcumin;curcumin;ultra high performance liquid chromatography（UPLC）
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发布时间： - 摘要：A new method coupling matrix solid phase dispersion（MSPD） with capillary electrophoresis was developed for the determination of acrylamide in rice product.The optimized conditions obtained in experiments were as follows：Florisil and C18 were used as a mixed dispersant with a mass ratio of 1∶4.The mass ratio of sample to dispersant was 5∶9.The mixture of 10 mL acetone-dichloromethane（6∶4） was used as elution solvent.Under the optimized experimental conditions，20 mmol/L borate solution（pH 8.4） was used as buffer.The sample was separated at a constant voltage of 15 kV.The linear range of acrylamide was in the range of 10-200 μg/mL，with a correlation coefficient（r） of 0.999 8.The limit of detection（LOD，S/N=3） was 0.62 μg/mL for acrylamide and the recoveries were in the range of 85.7%-96.4%.关键词：acrylamide;matrix solid-phase dispersion(MSPD);capillary electrophoresis;rice product
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发布时间： - 摘要：In this study，ascorbic acid was added into the sample solution to improve the signal intensity of Hg determined by inductively coupled plasma mass spectrometry(ICP-MS).Factors effecting the signal enhancement，such as concentrations of nitric acid and ascorbic acid，temperature and time of water bath，were optimized.According to the results，5% of HNO3，500 mg?L-1 of ascorbic acid and a 50 ℃ water bath for 20 min resulted in the highest sensitivity for Hg.A nearly 30 times signal enhancement factor could be achieved,and the detection limit of Hg was 1 ng?L-1.The calibration curve had a good linearity in the concentration range of 0.005-10.0 μg?L-1 with correlation coefficients above 0.999.The repeatability of the proposed method was obtained at 0.1 μg?L-1 of Hg2+ with the relative standard deviations（RSDs） of 5.6% by seven replicates.Besides，the mechanism for signal enhancement was investigated and discussed.关键词：mercury;ascorbic acid;signal enhancement;inductively coupled plasma mass spectrometry(ICP-MS)
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发布时间： - 摘要：Ratiometric sensing nanoprobes derivatized from luminescent dyes show great application in a nano or micro system as well as in a sensing material.Nowadays,a ratiometric nano sensing system has attracted a wide variety of attentions.In this review,the meaning of measuring oxygen concentration was introduced and the determination approaches for O2 was discussed.The research progress of nanosensors for O2 based on ratiometric fluorescence including their preparation,characteristics and applications,was systematically reviewed.关键词：oxygen;nanosensing;ratiometric fluorescence;preparation;applications;review
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