最新刊期
卷 32 ， 期 9 ， 2013
- 摘要：A new and rapid method was developed and validated for the simultaneous analysis of 15 alkaloids，including anabasine，gramine，eserine，pilocarpine，harmine，oxymatrine，thermopsine，koumine，gelsemine，tetrahydropalmine，evodiamine，sanguinarine，chelerythrine，strychnine and brucine in urine.The conditions of extraction，chromatography and mass spectrometry were optimized，and the matrix effects of the alkaloids were also examined.The detection of target compounds was performed by gas chromatography-tandem mass spectrometry in multiple-reaction monitoring(MRM) mode.The content of each alkaloid was determined by the external standard method.The linear ranges were 20-800 μg/L for eserine，harmine，koumine and strychnine，and 40-800 μg/L for other target alkaloids with correlation coefficients not less than 0.993 2.The mean recoveries were in the range of 60.0%-68.3% for anabasine，and 81.9%-114.4% for other alkaloids.The relative standard deviations(RSDs) were not more than 17.6% at three spiked concentration levels.The limits of detection(LODs) and quantitation(LOQs) were 4-20 μg/L and 10-40 μg/L，respectively.The method was rapid，sensitive and easy operation，and was suitable for the determination of trace alkaloids in urine samples of poisonous persons.关键词：gas chromatography-tandem mass spectrometry(GC-MS/MS);multiple-reaction monitoring(MRM);simultaneous determination;urine;toxic alkaloids
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发布时间： - 摘要：Oxidation effect of ?OH on sensitive amino acids in myofibrillar protein(MP) was studied based on Fe3+-H2O2-Vc oxidation system.The results showed that the oxidation effect of ?OH on amino acids in MP was selective.Among these amino acids，aspartic acid(Asp)，glycine(Gly) and leucine(Leu) were insensitive to oxidation，in which their contents did not change significantly after being oxidized.But cysteine(Cys)，methinnine(Met) and tyrosine(Tyr) were sensitive to oxidation，and their contents reduced gradually with the increase of H2O2 concentration，which resulted in the increase of ?OH generated in the Fe3+-H2O2-Vc oxidation system.The results also showed that the oxidation of MP could lead to the contents of protein carbonyl and bityrosine increasing，and sulfydryl decreasing.Further study showed that amino acids oxidation was concentration-dependent.The degree of oxidation increased with concentration of H2O2，and after being oxidized with 20.0 mmol/L H2O2 for 24 h，the contents of Cys，Met and Tyr decreased 13.3%，11.6% and 20.5%，respectively，compared with the control sample.Therefore，the oxidation-mediated structure changes of sensitive amino acids containing reactive groups were the major cause of protein oxidation.关键词：hydroxyl radical(?OH);myofibrillar protein(MP);sensitive amino acids;oxidation
- 1945
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发布时间： - 摘要：Eight sulfonamides，including sulfamethazine（SMZ），sulfathiazole（ST），sulfamonomethoxine（SMM-Na），sulfachloropyridazine（SCP），sulfafurazole（SIZ），sulfadimethoxine（SDM），sulfaphenazolum（SPP） and sulfanitran（SNT） in poultry and liver，were extracted by silica-supported ionic liquid-based matrix solid phase dispersion（S-ILs-MSPD），and determined by high performance liquid chromatography（HPLC）.The experimental conditions for the matrix solid phase dispersion extraction were optimized.The optimal conditions were as follows:dispersant:silica-supported ionic liquid containing 12% 1-hexyl-3-methylimidazolium hexafluorophosphate（［Hmim］PF6），washing solvent:petroleum ether，elution solvent:methanol.ratio of dispersant to sample:4∶1.Good linear relationships for eight sulfonamides were obtained in the range of 25-1 000 μg/kg with correlation coefficients not less than 0.997 4.The limits of detection and limits of quantitation of eight sulfonamides were in the ranges of 4.4-7.6 μg/kg and 14.7-25.3 μg/kg，respectively.The average recoveries ranged from 66. 2% to 98.7% with relative standard deviations（n=6） of 1.4%-9.0%.Compared with other extraction techniques，the present method has the advantages of low consumption and high sensitivity，and is suitable for the detection of sulfonamide residues in poultry products.关键词：ionic liquid;silica-supported ionic liquid;matrix solid phase dispersion;high performance liquid chromatography（HPLC）;sulfonamides
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发布时间： - 摘要：A gas chromatography-mass spectrometric（GC-MS）method was developed for the simultaneous determination of 4 kinds of antifouling biocides，including chlorothalonil，dichlofluanid，Sea-Nine 211 and Irgarol 1051 in marine coatings.The samples were extracted by ultrasonic method using ethyl acetate as solvent at room temperature，and the solid impurities were removed from the solution through the organic membrane，and then the target compounds were determined by GC-MS in selected ion monoitoring mode（SIM）.Under the optimal conditions，The standard calibration curves of chlorothalonil，dichlofluanid，Sea-Nine 211 and Irgarol 1051 were linear over the assayed range with correlation coefficients higher than 0.99.The detection limits（LOD，S/N≥3） ranged from 0.3 mg/kg to 1.3 mg/kg，and the limits of quantitation（LOQ，S/N≥10） ranged from 1.0 mg/kg to 4.3 mg/kg.The recoveries of the analytes in spiked samples ranged from 82.6% to 109.9%，with relative standard deviations（RSDs） less than 5%，The proposed method was applied in the determination of antifouling biocides in 6 commercially available marine antifouling coatings，and two of which were detected containing chlorothalonil，dichlofluanid and Sea-Nine 211，respectively.The method could meet the requirements for rapid and accuate determination of 4 antifouling biocides in marine coatings.关键词：marine coatings;antifouling biocides;chlorothalonil;dichlofluanid;Sea-Nine 211;Irgarol 1051;gas chromatography-mass spectrometry（GC-MS）
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- 1125
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- 5
发布时间： - 摘要：A simple method based on SPE coupled with HPLC-MS/MS was developed for the determination of 1H-benzotriazole(BTri),5-methyl-1H-benzotriazole(5-TTri),5,6-dimethyl-1H-benzotriazole(5,6-DMBTri),5-chloro-1H-benzotriazole(5-ClBTri),1-hydroxybenzotriazole(1-OHBTri),benzothiazole(BT),2-aminobenzothiazole(2-ABT) and 2-methylbenzothiazole(2-TBT) in surface water.Extraction and cleanup of surface water samples were performed on an HLB solid-phase extraction cartridge.The optimum extraction process was as follows:pH value of sample:3.0,sampling volume:200 mL,washing solvent:3 mL 10% methanol,eluting solvent:6 mL 20% acetone in methanol.Separation of target compounds was achieved on a Hypersil GOLD analytical column(150 mm×2.1 mm) with methanol-acetonitrile-water as mobile phase by gradient elution.Quantitative analysis by ESI-MS/MS was achieved using positive ion mode with multiple reaction monitoring mode.The calibration curves were linear in the range of 8-1 000 μg/L for 1-OHBTri,BT and 2-TBT,and 1.6-1 000 μg/L for rest of the compounds,with correlation coefficients more than 0.99.The average recoveries of target compounds were in the range of 59.8%-98.7% with relative standard deviations(RSDs,n=5) of 0.9%-12.5%.The instrumental limits of detection(S/N=3) for eight target compounds were in the range of 0.03-1.4 μg/L。关键词：benzotriazoles;benzothiazoles;solid-phase extraction;high performance liquid chro-matography-tandem mass spectrometry(HPLC-MS/MS);surface water
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- 7
发布时间： - 摘要：A combination of spectral experiment and molecular modeling techniques was used to characterize the binding mechanism between enrofloxacin（EFLX）and bovine lactoferrin（BLF）.The binding constants，energy transfer paremeters and thermodynamic parameters were investigated.The influence of EFLX on molecular conformation of BLF and the molecular models of EFLX-BLF were observed and established.The results showed that dynamic quenching exited between EFLX and BLF with moderate bond.The value of binding distances（r） was low，indicating the occurrence of energy transfer.The drug had conformation effect on BLF，which resulted in the decrease of hydrophobic environment of the binding domain in BLF.According to the obtained thermodynamic parameters，the main interaction forces between EFLX and BLF were hydrogen bonds and Van der Waals forces.The results of molecular modeling revealed that hydrogen bonds and Van der Waals forces are the main binding forces in the EFLX-BLF system，combining with hydrophobic interactions.Molecular modeling was agreed in the experiment results，which provided helpful reference for the study of molecular reaction mechanism of the quinolones binding with bovine lactoferrin.关键词：bovine lactoferrin;enrofloxacin;spectral experiment;molecular modeling
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发布时间： - 摘要：A high performance liquid chromatography-tandem mass spectrometric(LC-MS/MS) method was developed for the determination of kelevan residue in textiles.The sample was ultrasonically extracted with methanol-acetonitrile(1∶1) and the extract was purified with florisil column if necessary.The compound was separated on a Hypersil GOLD C18 column(100 mm×2.1 mm，5 μm) with 20% methanol-5 mmol/L ammonium acetate aqueous solution as mobile phase.The detection of kelevan was carried out by MS/MS with negative electrospray ionization under the multiple reaction monitoring mode using the external standard method.The calibration curve showed a good linearity in the range of 1.0-200.0 μg/L for the target compound.The limit of quantitation(S/N≥10) was 0.025 mg/kg.The recoveries of kelevan in cotton sample ranged from 90.6% to 103.4% at the spiked levels of 0.025，0.250，0.625 mg/kg with relative standard deviations(RSDs) of 3.3%-5.2%.With advantages of simplicity，accurancy and strong operability,the established method could be applied in the determination of kelevan in textiles.关键词：kelevan;textiles;liquid chromatography-tandem mass spectrometry(LC-MS/MS)
- 2522
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- 1130
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- 0
发布时间： - 摘要：A new method for analysis of vitexin and isovitexin in Crotalaria sessiliflora L.was developed by focused microwave-assisted aqueous two-phase extraction(FMAATPE) coupled with high performance liquid chromatography(HPLC).The experimental factors，including ethanol concentration，ratio of material to solvent，microwave power and extraction time were optimized based on the single factor test and orthogonal test.The analysis was performed by HPLC with UV detection at 340 nm.The mobile phase consisted of acetonitrile-water containing 0.5% phosphoric acid(14∶86).The optimum extraction conditions were as follows:two-phase composition:35% ethanol-16% ammonium sulfate，ratio of material to solvent:1∶50，microwave power:140 W， extraction time:20 min.The method was applied in the determination of vitexin and isovitexin in Crotalaria sessiliflora L.，with recoveries of 96.9%-103.8% and RSDs of 1.9%-2.6%.关键词：focused microwave-assisted extraction;aqueous two-phase extraction;Crotalaria sessiliflora L.;vitexin;isovitexin
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- 6
发布时间： - 摘要：The preparation and performance of an amperometric immunosensor，based on the use of layer-by-layer self-assembly technique，for the specific detection of prostate specific antigen(PSA) was reported. The immunosensor was developed by immobilizing the anti-PSA through layer-by-layer self-assembly of hyaluronic acid(HA)，thionine(Thi) and gold nanoparticles(nano-Au) on chitosan(Cs) modified glassy carbon electrode(GCE).The bovine serum albumin(BSA) was employed to block the possible remaining active sites of the nano-Au monolayer，avoiding the non-specific adsorption.The electrochemical characteristics of the immunosensor were studied by cyclic voltammetry(CV) and differential pulse voltammetry(DPV).The factors influencing the performance of the immunosensor were studied in detail.Under the optimized conditions，the linear ranges of the immunosensor were from 0.5 μg/L to 4 μg/L and from 4 μg/L to 25 μg/L with correlation coefficients more than 0.993，and a detection limit of 0.2 μg/L(estimated to be 3× the standard deviation of zero-dose response).The practical utilization of the immunosensor has been demonstrated through the determination of PSA in human serum samples.The results determined with the proposed immunosensor agreed fairly well with those obtained by the enzyme linked immune-sorbent assay(ELISA) technique.关键词：hyaluronic acid;thionine;layer-by-layer self-assembly;PSA;amperometric immunosensor
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发布时间： - 摘要：A comprehensive ultra performance liquid chromatography-tandem mass spectrometric（UPLC-MS/MS）method was developed for the determination of 3 sulfonylureas（carbutamide,chlorpropamide and tolbutamide）in cosmetics.Various cosmetic samples,including cream,aqua and ointment,were extracted with acidified methanol and then diluted with water.The extract was separated with reversed-phase UPLC using a binary eluent under isocratic conditions,and determined by MS/MS under the negative electrospray ionization mode with multiple reaction monitoring.The result indicated that a good separation of three compounds was obtained in 5 min.The calibration curves for 3 sulfonylureas were linear in the range of 0.001-0.1 mg/L with correlation coefficients more than 0.999.The limits of quantitation（LOQs）for 3 sulfonylureas were all 0.08 mg/kg.The mean recoveries at three spiked levels ranged from 80.9% to 117.0% with relative standard deviations（n=6） of 3.6%-97%.Under the optimal conditions,The method has good simplicity,sensitivity and stability,and is suitable for the rapid determination of 3 sulfonylureas in cosmetics.关键词：ultra-performance liquid chromatography-tandem mass spectrometry;cosmetics;carbutamide;chlorpropamide;tolbutamide
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发布时间： - 摘要：A graphene and phosphotungstic acid modified electrode (GO-PTA/GCE) was prepared by drop coating of graphene and phosphotungstic acid. The electrochemical behavior of theophylline(THEO) was studied on GO-PTA/GCE by cyclic voltammetry，and the influences of ratio of GO to PTA，amounts of GO and PTA，type and concentration of supporting electrolyte，and scan rate on the electrochemical behavior of THEO at GO-PTA/GCE were discussed by cyclic voltammetry. The properties of electrode surface were studied by the nyquist plots. The results indicated that，in 0.02 mol/L H2SO4 solution，there was an irreversible oxidation peak at 1.185 V on the modified electrode.The peak currents were linear with the square root of the scanning rate in the range of 100-800 mV/s，indicating that the electrode process of THEO was irreversible and controlled by diffusion. The electron number(n)，effective area(A) and diffusion coefficients(D) of THEO were calculated to be 1，0.116 9 cm2 and 6.675×10-5 cm2/s，respectively. Under the optimal conditions，the differential pulse voltammetric method was used to determine THEO. A good linear relationship between oxidation peak current and THEO concentration in the range of 6.0×10-7-1.0×10-4 mol/L was observed，and the detection limit was 5.5×10-7 mol/L. The method was successfully applied in the determination of THEO in water samples with recoveries of 92.6%-106.3%.关键词：theophylline;graphene;phosphotungstic acid;differential pulse voltammetry
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发布时间： - 摘要：Robust partial least square regression and partial robust M-estimator regression were applied in outlier detection and quantitative analysis of nitrogen content,oil content and glucosinolate content of rapeseeds by dint of infrared photoacoustic spectroscopy.The results showed that infrared photoacoustic spectroscopy can be used in the fast determination of rapeseeds′ qualities,and that robust regressions are superior to its classic versions in the avoiding of the interference caused by outliers to optimize quantitative analysis models,and in which partial robust M-regression(PRM)performs slightly better than robust partial least squares(RPLS).关键词：rapeseed;infrared photoacoustic spectroscopy;robust regression;nitrogen content;oil content;glucosinolate content
- 1949
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- 1141
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- 1
发布时间： - 摘要：A simple analysis method was developed for simultaneous determination of 1-propyl alcohol，diethylene glycol，propylene glycol，glycerol，triethylene glycol in tobacco by gas chromatography-mass spectrometry/selected ion mode（GC-MS/SIM）with 1，4-butanediol as internal standard.40 mesh powdered tobacco sample was ultrasonic extracted by methanol for 60 min directly.Under the optimal conditions，the calibration curves were linear in the range of 1-100 μg/mL，and the limits of detection（LODs） were in the range of 0.05-0.48 μg/mL.The spiked recoveries of analytes ranged from 90.2% to 103.7% with RSDs of 0.9%-3.0%.This method was suitable for the determination of 1-propyl alcohol，diethylene glycol，propylene glycol，glycerol，triethylene glycol in real tobacco samples with high sensitivity and convenient pre-treatment.关键词：gas chromatography-mass spectrometry（GC-MS）;tobacco;1-propyl alcohol;diethylene glycol;propylene glycol;glycerol;triethylene glycol
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发布时间： - 摘要：A large volume sample injection(LVSS)-reverse current flow accumulation capillary zone electrophoresis(CZE) method was used for the simultaneous separation and determination of magnolol,chlorogenic acid and caffeic acid in Qinggan Lidan oral.The result indicated that a best separation of three materials were obtained on an uncoated fused silica capillary column(50 cm×50 μm，effective length 36 cm) by using background electrolyte containing 40 mmol/L Na2B4O7，20mmol/L NaH2PO4，pH 9.0).The detection wavelength was set at 220 nm，with the separation voltage at 16 kV，the sample injection voltage at-12 kV and the injection time in 356 s.Under the optimum conditions， the separation of three compounds was performed within 20 min with relative standard deviations(RSDs) of peak area less than 4%.The detection limits(S/N=3) of magnolol，chlorogenic acid and caffeic acid were 184.2，36.07，77.99 ng/L，respectively.关键词：large volume sample injection(LVSS);capillary zone electrophoresis(CZE);magnolol;chlorogenic acid;caffeic acid
- 1865
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- 0
发布时间： - 摘要：A method for the determination of 5 chlorophenols（PCPs） and o-phenyphenol（OPP） in textiles using dispersive liquid-liquid microextraction（DLLME）coupled with gas chromatography-mass spectrometry（GC-MS） was proposed.Some important parameters affecting extraction efficiency，such as kind of extraction and dispersed solvents and their volume，concentration of K2CO3 were investigated.The optimal conditions were as follows：the sample was extracted with 0.15 mol/L K2CO3 solution in ultrasonic bath.Then 5 mL solution was derivatized with 0.1 mL acetic anhydride for 2 min，then extracted with 0.6 mL of isopropanol（as dispersive solvent） and 0.2 mL carbon tetrachloride （as extraction solution） in ultrasonic bath for 3 min，centrifuged for 3 min at a rate of 4 000 r/min.The lower organic phase was injected to analyze by GC-MS.Under the optimum conditions，the calibration curves were linear in the range of 0.001-1 mg/L，with correlation coefficients of 0.999 1-0.999 9.The detection limits（S/N=3） were in the range of 0.5-5 μg/kg.The average recoveries of the spiked samples were in the range of 87.2%-103.7% with relative standard deviations of 2.5%-4.8%.With the advantages of convinience，sensitivity，good recovery and repeatability，the method was suitable for the detection of 5 chlorophenols and o-phenyphenol in textile samples.关键词：dispersive liquid-liquid microextraction;gas chromatography-mass spectrometry;chlorophenol;o-phenyphenol;textiles
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- 4
发布时间： - 摘要：A simple and sensitive optical sensor for Ag+was developed based on its recognition of C-C mismatched base pair and nucleic acid molecule “light switch” property of Ru(phen)2(7,8-dimethyldipyridophenazine)2+.A self-complementary oligonucleotide containing cytosine-cytosine mismatched base pair，5-TACATACTATACTATCTA-3-(oligo-1)，was designed as the sequence for sensing of silver ion.In the absence of silver ion，the hybridization between the oligo-1 strands would not occur because of the existence of cytosine- cytosine mismatched base pair.However，after adding the silver ion，hybridization occurred between the two oligo-1 strands because of the formation of cytosine-Ag+-cytosine base pair，the formed double-helix DNA prevented the luminescence of nucleic acid molecule “light switch” Ru(phen)2(7,8-dimethyldipyridophenazine)2+ from the quenching of water.As a result，the luminescence of Ru(phen)2(dppx)2+ increased dramatically.Based upon this mechanism，a simple and sensitive method for the detection of silver ion was established.Different factors including concentrations of oligo-1，Ru(phen)2(dppx)2+，NaNO3，pH value and incubation time were investigated.The optimum conditions were as followins:Oligo-1:150 nmol/L，Ru(phen)2(dppx)2+:2.0 μmol/L，NaNO3:120 mmol/L，buffer:20 mmol/L pH 7.5 PBS，incubation time:30 min.Under the optimal conditions，the luminescence intensity was proportional to concentration of Ag+over the range of 10.0-120.0 nmol/L，with a correlation coefficient(r) of 0.995 7.The limit of detection(3δ/Slope) was 8.1 nmol/L.With a good selectivity，the method was applied in the determination of Ag+in practical samples with satisfactory results.关键词：DNA;nucleic acid molecular “light switch”;Ag+;optical sensors
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发布时间： - 摘要：By using a kind of molecular wire diphenylacetylene as the modifier and the binder,a new carbon paste electrode,which was denoted as carbon molecular wire electrode(CMWE),was prepared and used as the substrate electrode.Then graphene(GR) was electrodeposited on the surface of CMWE to get the modified electrode named as GR/CMWE.The electrochemical behaviors of dopamine(DA) on GR/CMWE were investigated by cyclic voltammetric method.A pair of the well-defined redox peaks were observed.Compared with that of CMWE,the redox peak currents increased greatly with the decrease of the peak-to-peak difference,indicating that the electrode reaction of DA on GR/CMWE was reversible.Under the optimal conditions,the peak currents had a good linear relationship with DA concentration in the range of 8.0×10-7 – 2.0×10-3 mol/L with a detection limit(3σ) of 2.55×10-7 mol/L.The commonly coexisting substances did not interfere DA detection, and the proposed method was applied in the determination of DA in injection samples with satisfactory results.关键词：graphene;carbon molecular wire electrode;dopamine;electrochemistry;differential pulse voltammetry
- 2080
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- 1058
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- 2
发布时间： - 摘要：An effective high performance liquid chromatographic(HPLC) method was developed for the determination of three curcuminoids，e.g.curcumin(CurⅠ)，demethoxycurcumin(CurⅡ) and bisdemethoxycurcumin(Cur Ⅲ)，in food.The analytes were extracted from homogenised samples using methanol，and separated on a YMCTM Carotenoid column(250 mm×4.6 mm，5 μm) by using methanol-water(A) and methyl teritary butyl ether(B) as mobile phase.The influences of experimental conditions were investigated.Under the optimal conditions，the calibration curves were linear in the range of 0.5-100 μg/mL，with correlation coefficients of 0.997 7-0.999 8.The average recoveries at spiked concentration range of 10-100 mg/kg ranged from 72.2% to 102% with relative standard deviations of 3.4%-13.8%.The limits of detection(LOD) of curcumin，demethoxycurcumin and bisdemethoxycurcumin were 6，5 mg/kg and 5 mg/kg，respectively.This method is suitable for the determination of curcuminoids in food.关键词：curcuminoids;high-performance liquid chromatography(HPLC);determination
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- 1130
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- 2
发布时间： - 摘要：A high performance liquid chromatography-tandem mass spectrometric method for the determination of erythromycin A and its metabolites including erythromycin A enolether and anhydroerythromycin A was developed.The sample was extracted with pH 7.0 phosphate buffer and cleaned-up with HLB column.The detection of target compounds was performed by LC-MS with electrospray positive ionization under the multiple reaction monitoring(MRM) mode.The internal standard method was used for quantitative analysis.Under the optimal conditions,the calibration curves were linear in the range of 2.0-100.0 μg/L with correlation coefficients more than 0.996.The limits of detection and the limits of quantitation were 0.5 μg/kg and 2.0 μg/kg,respectively.The recoveries of three compounds at fortified levels of 2.0,5.0 and 10.0 μg/kg ranged from 70.5% to 109.2% with RSDs less than 10%.The method,with higher recoveries and good precision,was suitable for the determination of erythromycin A and its metabolites in honey.关键词：honey;erythromycin;metabolite;high performance liquid chromatography-tandem mass spectrometry（HPLC-MS/MS）
- 2040
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- 1190
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- 3
发布时间： - 摘要：A method of high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS) coupled with immunoaffinity purification column was developed for the determination of biotin in infant formula milk powder.The sample was dissolved with phosphate buffer and cleaned up through biotin immunoaffinity column.The analyte was separated on an Ultimate AQ-C18(2.1 mm×100 mm,3 μm) column using methanol-0.1% formic acid(30∶70,by volume) as mobile phase with injection volume of 5 μL,at a flow rate of 0.3 mL/min and a column temperature of 40 ℃.The analysis of biotin was performed by HPLC-MS/MS in multiple reaction monitoring(MRM) mode via positive electrospray ionization(ESI) source.The quantitative ion was m/z 227.2,and qualitative ions were m/z 227.2,96.9,with excitation voltages of 10,30 V.A good linear calibration was obtained for biotin in the range of 0.1-1.0 μg/mL，with a method detection limit of 20.3 μg/kg.The average recoveries at three spiked levels were in the range of 92.7%-98.5% with RSDs of 1.7%-1.9%.With the advantages of easy sample handling,high sensitivity,good reproducibility,short analysis time,the method could meet for the determination of biotin in infant formula milk powder.关键词：immunoaffinity column;milk powder;biotin;high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS)
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发布时间： - 摘要：Fe3O4 nano-particles coated with silica were chemically modified with trimethoxyoctadecylsilane，and then used as the adsorbent for solid phase extraction of silver ion chelated with 5-Br-PADAP in environmental water samples.Coupled with flame atomic absorption spectrometry，a new analytical method for sensitive，rapid and simple determination of trace amount of silver ion in aqueous samples was developed.Effects of some experimental factors such as water sample pH，amount of adsorbent and chelating agent，oscillating time，eluent type and volume，coexisting ions，on the recovery of silver ion were investigated and optimized.The results showed that for 200 mL water sample，the optimal conditions were as follows：sample pH:7.0,adsorbent amount:0.1 g,volume of 5-Br-PADAP solution(0.5 mg/L)：0.6 mL,oscillating time:10 min.The adsorbed silver ion could be completely eluted off by using 6 mL 1.0 mol/L nitric acid.Under the optimized conditions，the detection limit for Ag+ was 0.15 μg/L with an enrichment factor of 31，and the relative standard deviation was 1.4%(10 μg/L，n=6).The proposed method was applied in the analysis of Ag+ in river water，lake water samples with spiked recoveries of 85.0%-94.8%.关键词：magnetic nano-particle;solid phase extraction;flame atomic absorption spectrometry;silver ion;water sample
- 1979
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- 3
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- 3
发布时间： - 摘要：A chemiluminescence emission between TiO2 nanoparticles(NPs) and Fe2+ in the air was observed.The chemiluminescence intensity could be enhanced in the presence of cetyltrimethyl ammonium bromide(CTAB).Moreover,the CL intensity of Fenton chemiluminescence reaction of Fe2+ with H2O2 could also be enhanced by TiO2 NPs.Based on this,a new chemiluminescence method for the detection of Fe2+ was developed.Under the optimal conditions,the calibration curve was linear in the range of 1.0×10-8 -1.0×10-6 mol/L with a detection limit of 4.0×10-9 mol/L.The relative standard deviation(n=5) for 1.0×10-7 mol/L Fe2+ was 3.9%.A brief discussion on the possible chemiluminescence reaction mechanism was also presented关键词：TiO2 nanoparticles;chemiluminescence;ferrous iron.
- 2087
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- 1175
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- 2
发布时间： - 摘要：In recent years,the study of self-assembled monolayers(SAMs),especially sulfur-gold system,has been attracting many attentions.3-mercaptopropionic acid(MPA) can form a stable and ordered single molecular film which shows a unique structure and special surface properties.This article reviews the important and elegant experiments that have been done in the field of MPA SAMS over the past 20 years.The preparation,structure,performance and application of MPA SAMs are discussed,and the future development of MPA SAMs is also proposed.关键词：self-assembled monolayers;3-mercaptopropionic acid;structure;performance;application
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