最新刊期
卷 30 ， 期 10 ， 2011
- 摘要：A sensitive method for the simultaneous determination of 21 phthalate acid esters(PAEs) in foods by gas chromatography-mass spectrometry(GC-MS) was firstly proposed.Different separation and purification methods were selected according to the types of food,and the chromatographic conditions were optimized.Qualitative detection and confirmation were acquired by the extraction of characteristic ions,and the interferences due to the complex matrixes were effectively eliminated,thus avoiding the possibility of false positive results.The mass spectrometric fragmentation rule of PAEs was also discussed in detail.The calibration curves of 21 compounds were linear in the range of 0.1-100 mg/L with correlation coefficients not less than 0.999 2.The quantitative limits(LOQs,S/N=10) ranged from 0.05 mg/kg to 0.5 mg/kg.The average spiked recoveries were in the range of 83%-106% at spiked levels of 0.10-10 mg/kg with relative standard deviations(RSDs,n=6)of 2.9%-5.5%.The method was successfully applied in the investigation of the PAEs distribution in foods and food packaging material of South China area,and the source of PAEs was also discussed in detail.关键词：phthalate acid esters;plasticizer;gas chromatography;mass spectrometry;foods;food packaging material
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发布时间： - 摘要：A gas chromatography and mass spectrometric(GC-MS) method was developed for the determination of in vivo metabolism of chlorpromazine, and its mass chromatograms were analyzed.Five female Wistar rats were gavaged with chlorpromazine hydrochloride and the 24-hr urine sample after administration were collected.The sample was hydrolyzed,and extracted by solid phase extraction(SPE).The metabolites were analyzed by GC-MS under EI and PCI mode.The mass chromatograms of the parent drug，blank urine and the sample were compared and identified.Sixteen compounds such as phenothiazine，2-chlorophenothiazine，N-(2-propenyl)-2-chlorophenothiazine，promazine，2-hydroxylphenothiazine，demethylchlorpromazine，3-hydroxylpromazine，promazine sulfoxide，2-chloro-7-hydroxylphenothiazine，chlorophenothiazine sulfone，7-hydroxylchlorpromazine，chlorpromazine sulfoxide，dihydroxylchlorpromazine，desmethylchlorpromazine sulfoxide，N-acetyl-demethylchlorpromazine，N-acetyl dedimethylchlorpromazine were identified as metabolites, in which 2-chlorophenothiazine，promazine，demethylchlorpromazine，7-hydroxylchlorpromazine and chlorpromazine sulfoxide were the main metabolites.The results suggested that at least three metabolic pathways for chlorpromazine, including oxidation，demethylation and dehalogenation, are operative in rats.关键词：chlorpromazine;urine;metabolites;GC-MS;fragmentation pathway
- 2299
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- 1888
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- 1
发布时间： - 摘要：An ultra performance liquid chromatography-tandem mass spectrometric （UPLC-MS/MS） method was developed for the determination of 66 organophosphrous pesticide residues in green onion,ginger,garlic and chili patse.The samples were extracted with acetonitrile assisted by ceramic homogenizers and separated by salting out method.The supernatants were purified by dispersive solid-phase extraction （Carb,C18 and PSA） prior to the UPLC-MS/MS analysis.The analytes were separated on an HSS T3 column,and indentified under positive electrospray ionization（ESI＋） and multiple reaction monitoring （MRM） mode.The matrix matched external standard calibration curves were used for the quantitative analysis.Under the optimal conditions,the quantitation limits of the method （S/N≥10） were 0.01 mg/kg.The calibration curves were linear in the range of 0.01-0.25 mg/L for all target compounds with correlation coefficients more than 0.99.The spiked recoveries at three levels of 0.01,0.02,0.10 mg/kg were in the range of 52%-117%,in which the recoveries for 92% pesticides were between 70% and 110%，and the relative standard deviations were in the range of 4.7%-16.9%.The method showed the advantages of simplicity,rapidness and sensitivity,and could meet the requirements for the determination of organophosphrous pesticide residues in preserved vegetables and their processed foods.关键词：ultra performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）;organophosphrous pesticides;residue;green onion;ginger;garlic;chili patse
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- 1786
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- 16
发布时间： - 摘要：A high performance liquid chromatographic（HPLC） method using on-line photochemical derivatization and fluorescence detection was developed for the simultaneous determination of nicotinic acid（NIA）,nicotinamide（NIC）,thiamine hydrochloride（B1）,riboflavin（B2） and cyanocobalamin（B12）.A self-built time/energy programmed photochemical reactor（PCR） with an ultraviolet mercury lamp was installed between the diode-array detector（DAD） and fluorescence detector（FLD） to convert the non-or weakly fluorescent vitamins into fluorescence compounds.The separation of NIA,NIC,B1,B12 and B2 was achieved within 12 min using 0.05 mol/L phosphate buffer（pH 5.8） -0.018 mol/L triethylamine -0.002 mol/L sodium heptane sulfonate（A） and methanol（B） as mobile phase by isocratic elution（A∶B,85∶15）.The separation and photochemical derivatization conditions were optimized.Under the optimal conditions,the calibration curves of five vitamins were linear in the range of 0.1-10.0 mg/L for NIA and NIC,0.2-20.0 mg/L for B1 and B12,0.01 -1.0 mg/L for B2 with correlation coefficient（r） more than 0.996.The limits of detection（LOD,3σ） ranged from 1.5 μg/L to 25.4 μg/L and the limits of quantitation（LOQs,10σ） were 5.0 -84.7 μg/L,which were better than those of the traditional HPLC/DAD method.The relative standard deviations（RSDs,n=7） were not more than 7.8% and the spiked recoveries were between 98% and 103%.The developed method was successfully applied in the determination of vitamins NIC,B1 and B2 in multivitamin tablets.关键词：water-soluble vitamins;photochemical derivatization;fluorescence detection;high performance liquid chromatography
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- 1314
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发布时间： - 摘要：A dispersive solid phase extraction coupled with gas chromatography-mass spectrometric method was established for the simultaneous determination of sixteen polycyclic aromatic hydrocarbons （PAHs） in fish and shrimp samples.The target analytes in samples were extracted twice with n-hexane-dichloromethane（1∶1,by volume）,followed by Florisil clean-up and sulfuric acid purification.The PAHs were analyzed by GC-MS under selected ion monitor（SIM） mode and quantified by the internal standard method.The procedure of sample pretreatment,the amount of dispersant and the instrument conditions were also optimized in the present study.Under the optimal conditions,good linearities were obtained in the range of 1-200 μg/L for sixteen analyzed compounds with correlation coefficients not less than 0.998 6.The limits of detection（S/N=3） ranged from 0.38 μg/kg to 1.5 μg/kg.The average recoveries of 16 PAHs from the carp and tilapia muscle samples at two spiked levels of 5 μg/kg and 15 μg/kg ranged from 90% to 102% with RSDs of 1.9%-8.5%.The method was simple,rapid and accurate,and could be used for the routine analysis of PAHs in fish and shrimp as well as other aquatic products.关键词：dispersive solid phase extraction;GC-MS;PAHs;fish;shrimp
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- 1385
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发布时间： - 摘要：Electrochemical behaviors,electrochemical kinetics and electrochemical determination of carbamazepine（CBZ） at nano-titanium dioxide（nano-TiO2） and 1-benzyl-3-methylimidazole hexafluorophosphate（［BnMIM］PF6） modified carbon paste electrode（nano-TiO2-［BnMIM］PF6/CPE） were investigated by cyclic voltammetry（CV）,chronocoulometry（CC）,chronoamperometry（CA） and square wave voltammetry（SWV）.The experimental results showed that the oxidation peak potential of CBZ was shifted negatively at nano-TiO2-［BnMIM］PF6/CPE and the oxidation peak current was greatly increased than that on CPE,which indicated that nano-TiO2-［BnMIM］PF6/CPE could catalyze the oxidation of CBZ well.The plot of oxidation peak current versus the square root of scanning rate in the potential range of 10-1 000 mV?s-1 showed a good linear relationship,as expected for a diffusion-controlled feature of the electrochemical process for CBZ at nano-TiO2-［BnMIM］PF6/CPE.The results of square wave voltammetry（SWV）indicated that the oxidation peak current was linearly proportional to the concentration of CBZ in the range of 2.0×10-5-5.0×10-4 mol?L-1 and 5.0×10-4-1.0×10-3 mol?L-1,with a detection limit of 4.3×10-7 mol?L-1.The method was applied in the determination of carbamazepine（CBZ） content in commercial pills,with relative standard deviations of 0.36%-0.77% and spiked recoveries of 98%-104%.关键词：carbamazepine;ionic liquid;nano-TiO2;electrocatalytic oxidation
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- 1159
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发布时间： - 摘要：The interaction between mustard gas（HD） and sodium dodecylsulfate（SDS） was analyzed by NMR information，e.g.chemical shift，diffusion，relaxation and the nuclear overhauser effect（NOE）.The chemical shift results indicated that HD was located around H4，H3 and H5 of SDS，and the hydrolysates of HD were near with H5.The ratios of spin-spin relaxation（T2） to spin-lattice relaxation（T1） of H4 and H5 increased after adding HD，indicating that the SDS micelle became loose and the hydrolysates of HD were located around H4 and H5.The ratio of self diffusion coefficient of D2O to SDS（Dw/Ds） increased from 12.03 to 18.12 after adding HD，indicating that the volume of SDS micelle was 1.5 times as big as that before adding HD.The two dimensional rotating frame nuclear overhauser enhancement spectroscopy（2D ROESY） experimental results showed that the hydrophobic chain of SDS became more curled after adding HD，and H8 of thiodiglycol was near by H5 of SDS.The kinetics parameters indicated that the reaction mechanism of HD in D2O was similar as that in SDS solution，but the rate constant of HD in SDS solution was at least 2 times faster than that in D2O.关键词：NMR;mustard;surfactant;interaction mechanism
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- 1207
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- 1
发布时间： - 摘要：Polypyrrole was synthesized on the surface of expanded graphite by potentiostatic electrodeposition.The imino group of polypyrrole combined with glutaraldehyde by crosslink to form a stable interface of expanded graphite/polypyrrole/glutaraldehyde.When human the IgG antibodies were immobilized onto the interface with glutaraldehyde as a cross linker，a novel electrochemical immonusensor was fabricated.The detection of human IgG is based on the principle of “sandwich” immunoassay.After the sensor was incubated in the solution containing IgG，the IgG fixed on the sensor surface combined with the HRP-labeled IgG second antibodies and the IgG antibodies to generate ternary immunocomplexes.HRP of the immunocomplexes can be used to catalyze the reduction of H2O2 and the determination of IgG can be realized by measuring the reduction current of H2O2.The experimental factors，including incubation temperature，incubation time，pH value and H2O2 concentration were investigated.Under the optimal conditions，the calibration curve was linear in the range of 1-50 mg?L-1 with a detection limit（S/N=3） of 3.5 μg?L-1 .This novel electrochemical immunosensor showed a high accuracy.The inter- and intra-groups relative standard deviations（RSDs） of this immunosensor for IgG determination were 2.4% and 4.0%，respectively.The electrochemical immunosensor was applied in the determination of IgG concentration in two real serum samples，with IgG concentrations of 9.60 g?L-1 and 9.28 g?L-1,respectively.The recoveries for both samples were 105%.With the advantages of simplicity，repeatability and low cost，the electrochemical immunosensor based on expanded graphite substrate is feasible to develop into a disposable electrochemical sensor for immunological test.关键词：expanded graphite;polypyrrole;electrochemical immunosensor
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- 1027
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发布时间： - 摘要：A high performance capillary electrophoresis method was established for the determination of indoleacetic acid（IAA） and gibberellic acid-3（GA3） in male floral buds of Populus tomentosa Carr..The samples were extracted with methanol by ultrasonic.Effects of experimental conditions,such as concentration and pH value of buffer,separation voltage,separation teperature and injection time on the separation efficiency were investigated.The optimal conditions were as follows:running buffer:pH 8.0 10 mmol/L borate-2.5 mmol/L SDS,injection time:5 s with a pressure of 50 mbar,determination temperature:25 ℃,applied voltage:22 kV,detection wavelength:200 nm.Under the optimum conditions,good linearities between peak areas and concentrations of IAA and GA3 were found in the ranges of 0.04-0.2 mg/L for IAA and 0.2-1.00 mg/L for GA3,with their correlation coefficients of 0.995 2 and 0.999 8,respectively.Two target analytes could be completely separated in 10 min.With the advantages of simple extraction,fast separation and high accuracy,the proposed method could be simultaneously applied in the determination of IAA and GA3 in plant samples.关键词：capillary electrophoresis;Populus tomentosa Carr.floral buds;IAA;GA3
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- 934
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发布时间： - 摘要：An ultra performance liquid chromatography-electrospray ionization triple-quadruple tandem mass spectrometric（UPLC-ESI MS/MS) method was established for the determination of residues of carbadox（CBX)，quinocetone（QCT)，mequindox（MEQ)，quinoxaline-2-carboxylic acid（QCA) and 3-methylquinoxaline-2-carboxylic acid（MQCA) in aquatic products.The samples were separately extracted with acetonitrile-ethyl acetate（50∶50) mixed solution and phosphate buffer，then purified with n-hexane.The separation of CBX，QCT，MEQ，QCA and MQCA was carried out on an ACQUITYTM BEH C18 column（1.7 μm，2.1 mm i.d.×100 mm) using methanol-acetronitril（11∶3) and 0.1% formic acid as mobile phases.The target compounds were confirmed and quantified by MS-MS under multiple-reaction monitering（MRM) mode with the external standard method.The results showed that there were good linear relationships between peak area and concentrations of five quinoxalines in the range of 5-50 μg/L，with correlation coefficients more than 0.998 and limits of quantitation（LOQs) of 1.0 μg/kg.The recoveries at spiked levels of 1.0-10 μg/kg ranged from 70% to 108% with relative standard deviations of 2.5%-11%.This method shortened the time of pre-treatment process，and the result was credible.It could satisfy the requirement of mass and fast analysis in the laboratory.关键词：UPLC-MS/MS;aquatic products;carbadox;quinocetone;mequindox;metabolites
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发布时间： - 摘要：A method of inductive coupled plasma mass spectrometry（ICP-MS） in mixed mode was established to determine the trace elements in plant samples,such as vegetables,fruit and rice.After digested by HNO3+H2O2,nine trace elements of As,Hg,Pb,Cd,Cr,Se,Cu,Ni and Zn in the samples were analyzed by using the technology of the collision/reaction cell with kinetic energy discrimination（KED） to eliminate the interference of mass spectrometry.74Ge,115In and 209Bi were also used to eliminate the matrix interference.The results indicated that the linear range of the method was beyond two orders of magnitude and the linear correlation coefficient was not less than 0.999 2.The limits of detection（LOD） were in the range of 0.8-40 μg/kg with RSDs of 0.6%-5.8%.The established method was used to determine the three certified reference materials of rice flour（GBW10010）,spinach（GBW10015） and apple（GBW10019）,and the analysis results were all in material reference range.The method was simple,rapid and accurate,and was suitable for the determination of Multi-elements in plant samples simultaneously.关键词：inductively coupled plasma mass spectrometry;collision cell technology;kinetic energy discrimination;plant samples;graphite dissolution
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- 3
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发布时间： - 摘要：A novel method was presented for identification of irradiated protein-rich food by HPLC with dissociative tyrosine.The procedure involved the homogenization of fresh sample with 0.1 mol/L HCl，followed by centrifugation to remove the cell debris and the solvent precipitation of protein with acetone at -20 ℃，then the tyrosine was separated by forming ion pair with trifluoroacetic acid on a C18 column.The average recoveries of the drugs ranged from 61% to 116% at the spiked levels of 100-800 μg/L.The method is simple and double-quick,and could be efficiently identified food sample irradiated at a dose of 5 kGy or above.关键词：dissociative tyrosine;irradiated food;HPLC;identification
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发布时间： - 摘要：The electrochemical behavior of acyclovir on the boron-doped diamond（BDD）electrode and its interaction with DNA in 0.10 mol/L phosphate buffer solution（pH 7.4） were studied by cyclic voltammetry and differential pulse voltammetric method-Compared with that on glassy carbon electrode,an oxidation peak of acyclovir at 1.17 V with lower background current and higher peak current was observed on the BDD electrode.The electrochemical oxidation mechanism of acyclovir on the BDD electrode was investigated by the relationships of the oxidation peak potential with the scan rate and pH value,and 2-electron-transfer and 2-proton-participation in the oxidation process of acyclovir were found.The study of interaction between different proportions of acyclovir and DNA indicated that acyclovir interacted DNA based on inset mode with binding site of 1.07 and binding constant of 4.47×106.The above results were further verified by the study of the interactions of acyclovir with single-stranded DNA and double-stranded DNA,respectively.关键词：boron-doped diamond electrode;acyclovir;DNA;interaction
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发布时间： - 摘要：A new method was established for the simultaneous determination of atrazine and ametryn residues in sugarcane juice by gas chromatography-mass spectrometry under selected ion monitoring(GC-MS/SIM).The pretreatment and chromatographic conditions were optimized.Under the optimal conditions,good linearities were obtained for 2 herbicides in the range of 0.00-0.60 mg/L with detection limits of 0.001 mg/L for both atrazine and ametryn.The average recoveries of 2 herbicide residues at spiked level of 0.050-0.100 mg/L were in the range of 93%-106%,with RSDs(n=6) of 4.4%-10.7%.The method showed the advantages of simplicity,repeatability,and sensitivity,and could be applied in the determination of atrazine and ametryn residues in sugarcane juice.关键词：gas chromatography-mass spectrometry;sugarcane;atrazine;ametryn
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发布时间： -
Simultaneous Determination of 18 Polyphenolic Compounds in Juice Concentrate Using UPLC-MS/MS Method
摘要：A UPLC-MS/MS method was developed for the determination of 18 polyphenolic compounds in juice concentrate.The sample was diluted with water and extracted completely by an Oasis(HLB) SPE column.The extract was evaporated to dryness and redissolved with methanol-0.1% formic acid.The targeted compounds were separated on an Acquity UPLC- BEH C18（1.7 μm× 2.1 mm×50 mm） column using 0.1% formic acid-methanol as mobile phase by linear gradient elution at a flow rate of 0.3 mL?min-1,and detected by MS/MS.The quantification of eighteen polyphenolic compounds was performed by the external standard method.Under the optimal conditions,the calibration curves of 18 polyphenolic compounds were linear in the range of 10.0-10 000.0 μg?L-1 with detection limits of 10.0-1 000.0 ng?g-1.The average recoveries for all the analytes were more than 70% with RSDs（n=6） less than 8.0%.With the advantages of good reproducibility,good recovery and high sensitivity,the method was suitable for the analysis of polyphenolic compounds in juice concentrate.关键词：ultra performance liquid chromatography-tandem mass spectrometry;polyphenolic compound;juice concentrate- 2122
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发布时间： - 摘要：A method was developed for the determination of tetrafluoroborate by ion-exclusion chromatography coupled with direct conductivity detection.Chromatographic separation was performed on a Shim-pack SCR-102H column.Influences of eluent and column temperature on retention time of tetrafluoroborate were investigated.The results indicated the retention time of tetrafluoroborate was increased with the increase of column temperature,and the retention process of tetrafluoroborate was endothermic.The optimal chromatographic conditions for determination of tetrafluoroborate were using 0.2 mmol/L p-toluenesulfonic acid as eluent with a column temperature of 40 ℃ and a flow rate of 1.0 mL/min.Under the optimal conditions,a good separation of tetrafluoroborate and common organic acids（such as,citric acid,malic acid,formic acid and acetic acid） was obtained.The retention time of tetrafluoroborate was 5.95 min.The determination were not interfered by the common inorganic anions（Cl-,Br-,NO-3,SO2-4）.The calibration curve was linear in the range of 3-100 mg/L with a detection limit（S/N=3） of 0.14 mg/L.The relative standard deviations（n=5） for retention time and peak area were 0.02% and 0.7%,respectively.The method was successfully applied in the determination of tetrafluoroborate in ionic liquids with spiked recoveries of 99%-102%.With the advantages of simplicity,accuracy and good repeatability,this method could be applied in the quality control analysis of relevant ionic liquids.关键词：Ion-exclusion chromatography;tetrafluoroborate;ionic-liquid;p-toluenesulfonic acid
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发布时间： - 摘要：An analytical method was established for the determination of free glycerol in biodiesel by using liquid-liquid extraction technique and high performance liquid chromatography（HPLC） with evaporative light-scattering detector（ELSD）.The biodiesel sample was extracted with acetonitrile-water（75∶25）,followed by centrifugation.The obtained aqueous layer was analyzed by HPLC-ELSD.The testing conditions of HPLC-ELSD were optimized and the optimal conditions were as follows:separation column:Inertsil NH2 column（250 mm×4.6 mm,5 μm）,mobile phase:mixture of acetonitrile and water（75∶25）,flow rate:1.0 mL/min,injection volume:30 μL,drift tube temperature:28 ℃,gas pressure of nebulizer:360 kPa.The result indicated that,under the optimal conditions,the calibration curve was linear over the content of free glycerol in biodiesel in the range of 3.73-302.0 mg/kg with a correlation coefficient of 0.999 8,and the limits of detection（S/N≥3）were 2.1 mg/kg.The spiked recoveries were in the range of 98%-101% with relative standard deviations（RSDs） of 0.59%-1.8%.The method was sensitive,accurate and reproducible,and could provide an efficient way for the determination of the content of free glycerol in biodiesel.关键词：high performance liquid chromatography（HPLC）;evaporative light-scattering detector（ELSD）;biodiesel;glycerol
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- 1031
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发布时间： - 摘要：A direct,simple and sensitive method was developed for the simultaneous separation and detection of nine organic acids,including lactate,acetate,propionate,formate,butyrate,malate,malonate,oxalate and citrate,in tobacco by anion exchange chromatography with eluent autogenerator and suppressed conductivity detection.The retention behaviors of organic acids on the anion exchange column were investigated using potassium hydroxide produced by EGC-ⅡKOH eluent autogenerator as eluent and the optimized gradient elution condition was obtained.The samples were prepared through extraction,filtration and dilution.The separation was performed on a Dionex IonPac AS11-HC anion exchange column.Under the optimized conditions,the calibration curves of all the analytes had good linearity.The detection limits ranged from 0.013 μg/L to 0.065 μg/L,and the relative standard deviations（RSDs） were in the range of 0.7%-3.0%.The spiked recoveries of nine organic acids were in the range of 93%-103%.The method was simple,accurate and sensitive，and could meet the actual requirements for the analysis of tobacco samples.关键词：ion chromatography;eluent autogeneration;detection;tobacco;organic acids
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- 1152
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- 19
发布时间： - 摘要：An ultra performance liquid chromatography-tandem mass spectrometric（UPLC-MS/MS） method was developed for the determination of sucralose in foodstuffs.The sample was extracted with water.Different purificatory methods like HLB cartridge purification or precipitators removing fat and protein were chosen according to different sample matrixs.The extract was separated with reversed-phase UPLC column using a binary eluent under isocratic conditions,and determined by tandem mass spectrometry under negative electrospray ionization mode with multiple reaction monitoring （MRM） mode. m/z 395.07/358.90 and m/z 397.07/360.90 were selected as two precursor-product ion pairs,in which m/z 395.07/358.90 was used for quantization.Under the optimal conditions,the calibration curve was linear over sucralose concentration in the range of 0.2-20 mg/L with quantitation limit of 0.4 mg/kg.The average recoveries of sucralose from Chinese spirit,modified milk and fried peanut kernels at three spiked levels of 0.4,4,10 mg/kg ranged from 85% to 98% with relative standard deviations （n=6） of 1.7%-5.0%.The method showed good simplicity,sensitivity and stability,and was suitable for the rapid determination of sucralose in foodstuffs.关键词：sucralose;UPLC-MS/MS;foodstuffs
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- 1150
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- 5
发布时间： - 摘要：Different extraction methods of bioactive component squalene in rices were studied and a new method was developed for the determination of squalene in rices.The squalene in rices from different areas were extracted by Soxhlet extract method,and analyzed by gas chromatography-tandem mass spectrometry（GC-MS/MS）.The results showed that the calibration curve was linear over the concentration of squalene in the range of 1-50 mg/L with a correlation coefficient of 0.998 7.The detection limit（LOD） was 0.1 mg/kg.The recoveries of squalene at two spiked levels of 5 mg/kg and 20 mg/kg were in the range of 96%-104% with relative standard deviations（RSDs） no more than 3.6%.The method was sensitive and reproducible,and could be used to distinguish effectively rices with different species,origins and qualities.关键词：gas chromatography-tandem mass spectrometry（GC-MS/MS）;squalene;rice;Soxhlet extract method
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- 1000
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- 4
发布时间： - 摘要：A fluorescent and colorimetric pH-indicator 1,5-bis(1-hydroxy-4-methoxphenyl)-1,4-pentadiene-3-one was synthesized based on the ketene structure as the fluorogen and phenolichydroxyl as the deprotonation group.The pH titration indicated that the probe displayed strong spectral sensitivity to pH in absorption spectra and fluorescence spectra.The absorption spectra were red-shifted and the solution undergoed distinct color changes from yellow to red with pH turning from acidity to basicity.The fluorescence spectra changed little under acidic solution,while there was more than 20-fold increase in the fluorescence emission intensity under basic solution.The fluorescence dissociation constant(pKa)was calculated to be 8.13 by using the formula of Henderson-Hasselbach,and the fluorescence quantum yield(in ethanol solution) was found to be 0.056 by comparing with the fluorescence quantum yield of quinine sulfate in 0.5 mol/L H2SO4.Furthermore,the probe also showed strong light resistant and anti-metal interference capability.关键词：diketene;colorimetric;fluorescent;pH-indicator
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- 1047
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- 6
发布时间： - 摘要：A liquid chromatography-tandem mass spectrometric method was developed for the determination of ｏ-tyrosine in γ-ray irradiated protein-rich food.The sample was homogenized and hydrolyzed with parenzyme at 37 ℃ for 24 h.The digestion solution was purified with n-hexane eliminating fat，deproteinated with zinc acetic acid solution，and then determined by HPLC-MS/MS.The quantitation limit was 0.1 mg/kg.The recoveries of ｏ-tyrosine at three spiked levels of 0.1，0.5 and 1.0 mg/kg were in the range of 80%-97%，with RSDs（n=6） of 6.3%-12.9%.The ｏ-tyrosine contents in chicken，pork，beef，fish and shrimp irradiated with 2，5,10 kGy of γ-ray ranged from 0.095 mg/kg to 0.677 mg/kg，which were obviously higher than those in the unirradiated meat samples,and presented linear relationships with the irradiance dose.The method showed good reproducibility and sensitivity.关键词：ｏ-tyrosine;γ-ray irradiated protein-rich food;HPLC-MS/MS
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- 1029
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发布时间： - 摘要：The molecularly imprinted monolithic column（MIPMC） has been attracting intensive attention in recent years as it combines the high stereo-selectivity of molecularly imprinted polymers with the advantages of excellent hydrodynamic characteristic，low flow resistance as well as simple preparation of monolithic materials，leading to potential applications in sample pretreatment and chromatographic analysis.In this paper，the methods of the preparation of molecularly imprinted monolithic column in a conventional chromatographic column and capillary column were introduced，and its applications in sample pre-concentration and chromatographic analysis in recent five years were summarized.The development trend of molecularly imprinted monolithic column was also prospected.关键词：molecularly imprinted monolithic column（MIPMC）;sample preparation;high performance liquid chromatography;capillary liquid chromatography;capillary electro-chromatography
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发布时间：
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