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2008 Volume 25 Issue 9
2008, 25(9): 1001-1006
Abstract:
New cholesterol-based low molecular mass organic gelators bearing a 2-,3-,or 4-pyridyl unit,which are denoted as 1,2,and 3,respectively,have been synthesized,and their corresponding salts(1',2',3') have also been prepared by simply protonating them with HCl.It is revealed that both the gelation behavior of the gelators and the micro-structures of the xerogels strongly depend on the relative position of N atom in the pyridyl unit and the protonation state of the pyridyl unit.FT-IR and 1H NMR studies demonstrate clearly that hydrogen bonding between the amide groups of the gelators play an important role in the formation of the organogels.XRD studies show that the primary assembly of compund 1 in benzene is similar to that of compund 1' in the same solvent,and furthermore is also similar to that of compund 1 in solid state.The repeat units of the three aggregates are almost the same,and are very close to the size of molecule 1.
New cholesterol-based low molecular mass organic gelators bearing a 2-,3-,or 4-pyridyl unit,which are denoted as 1,2,and 3,respectively,have been synthesized,and their corresponding salts(1',2',3') have also been prepared by simply protonating them with HCl.It is revealed that both the gelation behavior of the gelators and the micro-structures of the xerogels strongly depend on the relative position of N atom in the pyridyl unit and the protonation state of the pyridyl unit.FT-IR and 1H NMR studies demonstrate clearly that hydrogen bonding between the amide groups of the gelators play an important role in the formation of the organogels.XRD studies show that the primary assembly of compund 1 in benzene is similar to that of compund 1' in the same solvent,and furthermore is also similar to that of compund 1 in solid state.The repeat units of the three aggregates are almost the same,and are very close to the size of molecule 1.
2008, 25(9): 1007-1010
Abstract:
The diffusivity of point defects in the passive film formed on X80 pipeline steel in simulated soil environment was calculated by means of capacitance measurement and point defect model(PDM).The calculated result was testified by experimental steady current density and PDM.Two calculated results all show that the order of magnitude of diffusivity is about 1×10-17 cm2/s.
The diffusivity of point defects in the passive film formed on X80 pipeline steel in simulated soil environment was calculated by means of capacitance measurement and point defect model(PDM).The calculated result was testified by experimental steady current density and PDM.Two calculated results all show that the order of magnitude of diffusivity is about 1×10-17 cm2/s.
2008, 25(9): 1011-1016
Abstract:
ZnS nanoparticles were synthesized and characterized.The synthetic and modified conditions of ZnS nanoparticles,such as pH value,reaction temperature,the molar ratio of Zn(Ac)2,Na2S and the stabilizing reagent(EDTA) and the concentration of L-cysteine,were optimized.Under the best conditions of synthesis and modification,functionalized ZnS nanoparticles with sphere shape and a diameter of 150 nm were obtained.UV-Vis,fluorescence and attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectroscopies were used to study the interaction of ZnS nanoparticles modified by L-cysteine and Bovine hemoglobin.The results indicate that the fluorescence of functionalized ZnS nanoparticles was significantly quenched by Bovine hemoglobin.The quenching constant calculated according to Stern-Volmer equation was 1.12×106 L/mol.It is inferred from this result that the effect of Bovine hemoglobin on the fluorescence of functionalized ZnS nanoparticles was a static quenching and strong interaction taking place between Bovine hemoglobin molecules and functionalized ZnS nanoparticles.The strong interaction significantly affected the second structure of BHb molecules,which was confirmed by ATR-FTIR observations.
ZnS nanoparticles were synthesized and characterized.The synthetic and modified conditions of ZnS nanoparticles,such as pH value,reaction temperature,the molar ratio of Zn(Ac)2,Na2S and the stabilizing reagent(EDTA) and the concentration of L-cysteine,were optimized.Under the best conditions of synthesis and modification,functionalized ZnS nanoparticles with sphere shape and a diameter of 150 nm were obtained.UV-Vis,fluorescence and attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectroscopies were used to study the interaction of ZnS nanoparticles modified by L-cysteine and Bovine hemoglobin.The results indicate that the fluorescence of functionalized ZnS nanoparticles was significantly quenched by Bovine hemoglobin.The quenching constant calculated according to Stern-Volmer equation was 1.12×106 L/mol.It is inferred from this result that the effect of Bovine hemoglobin on the fluorescence of functionalized ZnS nanoparticles was a static quenching and strong interaction taking place between Bovine hemoglobin molecules and functionalized ZnS nanoparticles.The strong interaction significantly affected the second structure of BHb molecules,which was confirmed by ATR-FTIR observations.
2008, 25(9): 1017-1021
Abstract:
In Britton-Robinson buffer media with different pH values,some acidic triphenylmethane dyes can form ion-association complexes with pioglitazone hydrolchloride respectively.The maximum fading wavelength of complexes is between 558 nm and 616 nm,and the maximum absorption wavelength is between 426 nm and 450 nm.The concentration of pioglitazone hydrolchloride follows Beer's law for the tight absorption in a range of 3.1×10-7 mol/L and 1.55×10-5 mol/L,the apparent molar absorptivity is between 1.47×104 L/(mol·cm) and 9.50×104 L/(mol·cm),and the detection limit is between 3.32×10-5 g/L and 2.57×10-4 g/L respectively.A sensitive spectrophotometric method is therefore developed for the determination of pioglitazone hydrolchloride.The method has a high sensitivity and a fairly good selectivity,and has been applied to the detemfination of pioglitazone hydrolchloride in urine samples,mixture samples and blood samples,with satisfactory results.
In Britton-Robinson buffer media with different pH values,some acidic triphenylmethane dyes can form ion-association complexes with pioglitazone hydrolchloride respectively.The maximum fading wavelength of complexes is between 558 nm and 616 nm,and the maximum absorption wavelength is between 426 nm and 450 nm.The concentration of pioglitazone hydrolchloride follows Beer's law for the tight absorption in a range of 3.1×10-7 mol/L and 1.55×10-5 mol/L,the apparent molar absorptivity is between 1.47×104 L/(mol·cm) and 9.50×104 L/(mol·cm),and the detection limit is between 3.32×10-5 g/L and 2.57×10-4 g/L respectively.A sensitive spectrophotometric method is therefore developed for the determination of pioglitazone hydrolchloride.The method has a high sensitivity and a fairly good selectivity,and has been applied to the detemfination of pioglitazone hydrolchloride in urine samples,mixture samples and blood samples,with satisfactory results.
2008, 25(9): 1022-1026
Abstract:
Nanocompositions(Fe3O4/PVA)/SiO2 have been prepared by three-step method(co-precipitation,miniemulsion polymerization,Stöber process) and structurally characterized by TEM.According to the image of Fe3O4/PVA/SiO2 by TEM,the morphology is obviously core-shell structure: the average diameter of Fe3O4/PVAc is 100 nm;the diameter of(Fe3O4/PVA)/SiO2 is controllable within a certain range(100~500 nm).And(Fe3O4/PVA)/SiO2-glutaraldehyde can capture BSA within a certain time at a certain tempe-rature.
Nanocompositions(Fe3O4/PVA)/SiO2 have been prepared by three-step method(co-precipitation,miniemulsion polymerization,Stöber process) and structurally characterized by TEM.According to the image of Fe3O4/PVA/SiO2 by TEM,the morphology is obviously core-shell structure: the average diameter of Fe3O4/PVAc is 100 nm;the diameter of(Fe3O4/PVA)/SiO2 is controllable within a certain range(100~500 nm).And(Fe3O4/PVA)/SiO2-glutaraldehyde can capture BSA within a certain time at a certain tempe-rature.
2008, 25(9): 1027-1031
Abstract:
To establish an extraction method for trans-chrysanthemic acid using lipophilic L-tartaric esters and hydroxypropyl-β-cyclodextrin as chiral selector,the distribution of trans-CA enantiomers was examined in aqueous methanol solution containing HP-β-CD,1,2-dichloroethane organic solution and lipophilic L-tartaric esters.The influences of the concentrations of L-tartaric esters and HP-β-CD,the length of alkyl chain of L-tartaric esters,pH and the concentration of aqueous methanol solution on the partition coefficient(K) and separation factor(α) of trans-CA were investigated.The experiment results show that the complex formed by L-tartaric esters with S enantiomers is stabler than that by L-tartaric ester with R enantiomers.With the increase of the concentration of L-tartaric esters,K and α increased;with the increase of the concentration of HP-β-CD,K and α increased firstly,and then decreased,K and α were the highest when the concentration of HP-β-CD was 3 mmol/L.The length of alkyl chain of L-tartaric esters has great influences on K and α.With the increase of pH,K and α decreased;with further increasing the concentration of methanol,K and α decreased,K and α were the highest when the concentration of methanol was 10%.
To establish an extraction method for trans-chrysanthemic acid using lipophilic L-tartaric esters and hydroxypropyl-β-cyclodextrin as chiral selector,the distribution of trans-CA enantiomers was examined in aqueous methanol solution containing HP-β-CD,1,2-dichloroethane organic solution and lipophilic L-tartaric esters.The influences of the concentrations of L-tartaric esters and HP-β-CD,the length of alkyl chain of L-tartaric esters,pH and the concentration of aqueous methanol solution on the partition coefficient(K) and separation factor(α) of trans-CA were investigated.The experiment results show that the complex formed by L-tartaric esters with S enantiomers is stabler than that by L-tartaric ester with R enantiomers.With the increase of the concentration of L-tartaric esters,K and α increased;with the increase of the concentration of HP-β-CD,K and α increased firstly,and then decreased,K and α were the highest when the concentration of HP-β-CD was 3 mmol/L.The length of alkyl chain of L-tartaric esters has great influences on K and α.With the increase of pH,K and α decreased;with further increasing the concentration of methanol,K and α decreased,K and α were the highest when the concentration of methanol was 10%.
2008, 25(9): 1032-1036
Abstract:
The interactions between human serum albumin(HSA) and acidic chromic blue K(ACBK) was investigated by fluorescence spectroscopy and Fourier transform infrared spectroscopy(FT-IR) under simulative physiological conditions.The quenching constants of HSA by ACBK suggested ACBK could quench the intrinsic fluorescence of HSA by static quenching.According to fluorescence resonance energy transfer(FRET),the distance and energy transfer efficiency(E) between the donor(HSA) and the acceptor(ACBK) were calculated to be 2.29 nm and 0.078,respectively.The relationship of fluorescence quenching and the changes of HSA secondary structure induced by ACBK binding was investigated by combining the results of fluorescence and FT-IR.The fluorescence results and FT-IR study suggested that hydrophobic interactions were the predominant intermolecular force and caused the secondary structure of HSA to change from α-helix and β-sheets to β-turns and random coils respectively.Upon HSA-ACBK complexing,the α-helix structure reduced by more than 9%,and the β-sheet reduced by 2%,while the β-turn increased by 6%,and the random coil increased by 5%.
The interactions between human serum albumin(HSA) and acidic chromic blue K(ACBK) was investigated by fluorescence spectroscopy and Fourier transform infrared spectroscopy(FT-IR) under simulative physiological conditions.The quenching constants of HSA by ACBK suggested ACBK could quench the intrinsic fluorescence of HSA by static quenching.According to fluorescence resonance energy transfer(FRET),the distance and energy transfer efficiency(E) between the donor(HSA) and the acceptor(ACBK) were calculated to be 2.29 nm and 0.078,respectively.The relationship of fluorescence quenching and the changes of HSA secondary structure induced by ACBK binding was investigated by combining the results of fluorescence and FT-IR.The fluorescence results and FT-IR study suggested that hydrophobic interactions were the predominant intermolecular force and caused the secondary structure of HSA to change from α-helix and β-sheets to β-turns and random coils respectively.Upon HSA-ACBK complexing,the α-helix structure reduced by more than 9%,and the β-sheet reduced by 2%,while the β-turn increased by 6%,and the random coil increased by 5%.
2008, 25(9): 1037-1041
Abstract:
DNA modified carbon nanotubes electrodes are widely used in various fields and the immobilization step is of vital importance to them.Based on the carbon nanotubes(CNTs)-modified glassy carbon(GC)(CNTs/GC) electrode,two kinds of DNA-modified CNTs/GC(DNA-CNTs/GC) electrodes were fabricated by means of the absorption method and covalent bonding method.The electrochemical characteristics of the DNA-CNTs/GC electrodes were investigated via the cyclic voltammetry,differential pulse voltammetry and electrochemical impedance technique with Th as electrochemically active indicator.The results indicate that the DNA-CNTs/GC electrode prepared with the covalent bonding method possesses advantages of a large immobilization amount of DNA on the electrode surface and good stability,which could be used in the fields of electrochemical gene biosensors.
DNA modified carbon nanotubes electrodes are widely used in various fields and the immobilization step is of vital importance to them.Based on the carbon nanotubes(CNTs)-modified glassy carbon(GC)(CNTs/GC) electrode,two kinds of DNA-modified CNTs/GC(DNA-CNTs/GC) electrodes were fabricated by means of the absorption method and covalent bonding method.The electrochemical characteristics of the DNA-CNTs/GC electrodes were investigated via the cyclic voltammetry,differential pulse voltammetry and electrochemical impedance technique with Th as electrochemically active indicator.The results indicate that the DNA-CNTs/GC electrode prepared with the covalent bonding method possesses advantages of a large immobilization amount of DNA on the electrode surface and good stability,which could be used in the fields of electrochemical gene biosensors.
2008, 25(9): 1042-1046
Abstract:
Novel PA6/epoxy resin(EP)/SiO2 nanocomposites were prepared by mixing caprolactam with hydrolysis solution of modified precursor,which was synthesized by tetraethoxysilane(TEOS) and epoxy resin,via in situ polymerization.The structure and properties of the nanocomposites were investigated by fourier transform infrared spectroscopy(FTIR),mechanical tests,dynamic mechanical analysis(DMTA),scanning electron microscopy(SEM),transmission electron microscopy(TEM),atomic force microscopy(AFM) and thermal gravimetric analysis(TGA),etc.The results show that silica particles were homogeneously dispersed in the material matrix.The diameter of nano-silica is about 30 nm.The mechanical properties show a tendency to increase and then decrease with the increase of the silica content and have maximum values at 3% silica content.Compared with those of pure PA6,the tensile strength,impact strength,flexural strength and elongation at break of PA6/EP/silica nanocomposites were improved by about 28%,360%,43% and 45%,respectively.
Novel PA6/epoxy resin(EP)/SiO2 nanocomposites were prepared by mixing caprolactam with hydrolysis solution of modified precursor,which was synthesized by tetraethoxysilane(TEOS) and epoxy resin,via in situ polymerization.The structure and properties of the nanocomposites were investigated by fourier transform infrared spectroscopy(FTIR),mechanical tests,dynamic mechanical analysis(DMTA),scanning electron microscopy(SEM),transmission electron microscopy(TEM),atomic force microscopy(AFM) and thermal gravimetric analysis(TGA),etc.The results show that silica particles were homogeneously dispersed in the material matrix.The diameter of nano-silica is about 30 nm.The mechanical properties show a tendency to increase and then decrease with the increase of the silica content and have maximum values at 3% silica content.Compared with those of pure PA6,the tensile strength,impact strength,flexural strength and elongation at break of PA6/EP/silica nanocomposites were improved by about 28%,360%,43% and 45%,respectively.
2008, 25(9): 1047-1051
Abstract:
We have prepared waterborne polyurethane(WPU) nano-SiO2 composites by in situ polymerization,during which modified silica sol was first mixed with the N-methyl-pyrolidone(NMP),and then polyme-rization was carried out with the addition of isophorone diiocyanate(IPDI),polycaprolactone(PCL) dimethylol-propionic acid(DMPA) and dibutyltin dilaurate.Effects of nano-silica content on the thermal and mechanical properties of WPU/nano-silica composites were investigated by thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),transmittance electron microscopy(TEM) and dynamic mechanical analysis(DMA).The experiment results show that the nano-silica particles were well dispersed in the WBPU solution when the silica content was lower than 3.0%,a wider Tg gap and higher microphase separation degree between soft and hard segment were observed for WPUNS,and the thermal degradation temperature of the composite was higher than that of a pure WPU at temperature over 50 ℃.Besides,as the nano-silica content was increased from 0 to 0.5%,the elongation at break and water swell were decreased from 550% to 430% and 16.8% to 4.5%,respectively,while,the tensile strength was increased from 3.4 MPa to 5.95 MPa.As the nano-silica content was increased to 2.5%,the elongation at break and water swell decreased to 210% and 2.3%,and the tensile strength increased to 7.58 MPa.
We have prepared waterborne polyurethane(WPU) nano-SiO2 composites by in situ polymerization,during which modified silica sol was first mixed with the N-methyl-pyrolidone(NMP),and then polyme-rization was carried out with the addition of isophorone diiocyanate(IPDI),polycaprolactone(PCL) dimethylol-propionic acid(DMPA) and dibutyltin dilaurate.Effects of nano-silica content on the thermal and mechanical properties of WPU/nano-silica composites were investigated by thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),transmittance electron microscopy(TEM) and dynamic mechanical analysis(DMA).The experiment results show that the nano-silica particles were well dispersed in the WBPU solution when the silica content was lower than 3.0%,a wider Tg gap and higher microphase separation degree between soft and hard segment were observed for WPUNS,and the thermal degradation temperature of the composite was higher than that of a pure WPU at temperature over 50 ℃.Besides,as the nano-silica content was increased from 0 to 0.5%,the elongation at break and water swell were decreased from 550% to 430% and 16.8% to 4.5%,respectively,while,the tensile strength was increased from 3.4 MPa to 5.95 MPa.As the nano-silica content was increased to 2.5%,the elongation at break and water swell decreased to 210% and 2.3%,and the tensile strength increased to 7.58 MPa.
2008, 25(9): 1052-1056
Abstract:
A novel double-hydrophilic block copolymer(DHBC) poly(vinyl pyrrolidone)-block-poly(methacrylic acid)(PVP-b-PMAA),was synthesized via reversible addition fragmentation chain transfer(RAFT) polymerization.The structure of the resulting copolymer was characterized by 1H NMR,and the molecular weight of the copolymer was 28 800 determined by gel permeation chromatography(GPC),and the molecular weight distribution index was 1.42.The morphology of calcium carbonate(CaCO3) in the presence of PVP-b-PMAA block copolymer was studied.It was found that with the increase of the mass concentration of the block copolymer,the morphology of the CaCO3 particles changed from layered to aggregate.When the mass concentration of the block copolymer was 1 g/L,some cavities were observed in the aggregated crystals.
A novel double-hydrophilic block copolymer(DHBC) poly(vinyl pyrrolidone)-block-poly(methacrylic acid)(PVP-b-PMAA),was synthesized via reversible addition fragmentation chain transfer(RAFT) polymerization.The structure of the resulting copolymer was characterized by 1H NMR,and the molecular weight of the copolymer was 28 800 determined by gel permeation chromatography(GPC),and the molecular weight distribution index was 1.42.The morphology of calcium carbonate(CaCO3) in the presence of PVP-b-PMAA block copolymer was studied.It was found that with the increase of the mass concentration of the block copolymer,the morphology of the CaCO3 particles changed from layered to aggregate.When the mass concentration of the block copolymer was 1 g/L,some cavities were observed in the aggregated crystals.
2008, 25(9): 1057-1060
Abstract:
To study the effect of β-cyclodextrin(β-CD) on the adsorptive action of cetyl trimethylammonium bromide(CTAB) in Na-montmorillonite,the inclusion activity between β-CD and CTAB was studied by measuring the surface tension of the solution at 303.15 K.The result shows that the host-guest inclusion complex's stoichiometric ratio is 1.53:1.By comparing the adsorption rate before and after inclusion,the mechanism that the adsorption capacity of CTAB in Na-montmorillonite is decreased by β-CD is studied.The adsorption capacity of CTAB in Na-montmorillonite decreased by about 75% after inclusion by β-CD.Simulated oil displacement experiment confirmed that the utilization ratio of CTAB has been increased significantly after CTAB having been included.
To study the effect of β-cyclodextrin(β-CD) on the adsorptive action of cetyl trimethylammonium bromide(CTAB) in Na-montmorillonite,the inclusion activity between β-CD and CTAB was studied by measuring the surface tension of the solution at 303.15 K.The result shows that the host-guest inclusion complex's stoichiometric ratio is 1.53:1.By comparing the adsorption rate before and after inclusion,the mechanism that the adsorption capacity of CTAB in Na-montmorillonite is decreased by β-CD is studied.The adsorption capacity of CTAB in Na-montmorillonite decreased by about 75% after inclusion by β-CD.Simulated oil displacement experiment confirmed that the utilization ratio of CTAB has been increased significantly after CTAB having been included.
2008, 25(9): 1061-1064
Abstract:
A kind of new thickeners with enhanced resistance ability to electrolyte was prepared.Exfoliated inorganic montmorillonite was used as an effective multifunctional cross-linker.In these composites polymer chains were grafted on the clay surface at one or both ends.The rheology of these thickeners in pure water,NaCl or NaHCO3 solution has been studied.Experimental results reveal that these composites show enhanced resistance ability to electrolyte.The viscosity of 5% bis-cross-linked thickener decreased from 118 Pa·s to 6 Pa·s in the presence of 5 mL of 2 mol/L NaCl solution.The viscosity of montmorillonite cross-linked thickener decreased from 63 Pa·s to 24 Pa·s in the presence of 5 mL of 2 mol/L NaCl solution.When the amount of NaCl solution was 8 mL,the viscosity still maintained 16.5 Pa·s.
A kind of new thickeners with enhanced resistance ability to electrolyte was prepared.Exfoliated inorganic montmorillonite was used as an effective multifunctional cross-linker.In these composites polymer chains were grafted on the clay surface at one or both ends.The rheology of these thickeners in pure water,NaCl or NaHCO3 solution has been studied.Experimental results reveal that these composites show enhanced resistance ability to electrolyte.The viscosity of 5% bis-cross-linked thickener decreased from 118 Pa·s to 6 Pa·s in the presence of 5 mL of 2 mol/L NaCl solution.The viscosity of montmorillonite cross-linked thickener decreased from 63 Pa·s to 24 Pa·s in the presence of 5 mL of 2 mol/L NaCl solution.When the amount of NaCl solution was 8 mL,the viscosity still maintained 16.5 Pa·s.
2008, 25(9): 1065-1068
Abstract:
Tetra-(p-hydroxylphenyl)porphyrin photosensitizer loaded with magnetic nanoparticles were prepared by means of emulsification and chemical co-precipitation.The morphology and size of the nanoparticles were analyzed by transmission electronic microscopy and X-ray diffraction,and their chemical structures were also analyzed by infrared spectroscopy.The magnetic response property was observed on a vibrating samples magnetometer.The content of photosensitizer was measured by UV-Vis spectrum.Their photodynamic activity against human Lovo colonic-carcinoma cell line in vitro was evaluated by MTT assay.The results reveal that the magnetic nanoparticles are regular sphere with a size of smaller than 50 nm,and the Fe3O4 particles were coated by the Dextran-40,the mass magnetic susceptibility was 68.27 emu/g,the content of porphyrin photosensitizer was 8.5%.The growth inhibitory rate of Volo cells was 81.85% after they were treated with magnetic nanoparticles,in which 1×10-6 mol/L of tetra-(p-hydroxylphenyl)porphyrin was loaded,followed by irradiation of visible light for 30 min.
Tetra-(p-hydroxylphenyl)porphyrin photosensitizer loaded with magnetic nanoparticles were prepared by means of emulsification and chemical co-precipitation.The morphology and size of the nanoparticles were analyzed by transmission electronic microscopy and X-ray diffraction,and their chemical structures were also analyzed by infrared spectroscopy.The magnetic response property was observed on a vibrating samples magnetometer.The content of photosensitizer was measured by UV-Vis spectrum.Their photodynamic activity against human Lovo colonic-carcinoma cell line in vitro was evaluated by MTT assay.The results reveal that the magnetic nanoparticles are regular sphere with a size of smaller than 50 nm,and the Fe3O4 particles were coated by the Dextran-40,the mass magnetic susceptibility was 68.27 emu/g,the content of porphyrin photosensitizer was 8.5%.The growth inhibitory rate of Volo cells was 81.85% after they were treated with magnetic nanoparticles,in which 1×10-6 mol/L of tetra-(p-hydroxylphenyl)porphyrin was loaded,followed by irradiation of visible light for 30 min.
2008, 25(9): 1069-1072
Abstract:
A micellar electrokinetic chromatography(MEKC) method based on on-line sweeping technique and ultraviolet spectrophotometry(UV) were compared for a fast determination of paraquat concentration in serum.For MEKC,the blood sample pretreatment required only the precipitation of protein contents by 10% trichloroacetic acid.In the running buffer of 50 mmol/L phosphate and 80 mmol/L sodium dodecyl sulfate(SDS)(pH=2.5),the paraquat in the sample was successfully detected within 600 s,in a uncoated fused-silica capillary column(48.5 cm×50 μm,effective length 40 cm) at a voltage of 22 kV,and a injection pressure of 5 kPa,with UV detection at 260 nm.For UV,the sample was deproteinizated by 20% trichlo-racetic acid,50 μL microcell,the determination wavelength was 257 nm.Through the comparative analysis it shows that although ultraviolet spectrophotometry surpassed Sweeping-MEKC in the linear correlation coefficient and the reproduction of quantity,the limit of detection of UV was inferior to that of Sweeping-MEKC.The determitatiom limit of the former is lower,so it is applicable to the determination of the paraquat concentration in serum before and after hemoperfusion.
A micellar electrokinetic chromatography(MEKC) method based on on-line sweeping technique and ultraviolet spectrophotometry(UV) were compared for a fast determination of paraquat concentration in serum.For MEKC,the blood sample pretreatment required only the precipitation of protein contents by 10% trichloroacetic acid.In the running buffer of 50 mmol/L phosphate and 80 mmol/L sodium dodecyl sulfate(SDS)(pH=2.5),the paraquat in the sample was successfully detected within 600 s,in a uncoated fused-silica capillary column(48.5 cm×50 μm,effective length 40 cm) at a voltage of 22 kV,and a injection pressure of 5 kPa,with UV detection at 260 nm.For UV,the sample was deproteinizated by 20% trichlo-racetic acid,50 μL microcell,the determination wavelength was 257 nm.Through the comparative analysis it shows that although ultraviolet spectrophotometry surpassed Sweeping-MEKC in the linear correlation coefficient and the reproduction of quantity,the limit of detection of UV was inferior to that of Sweeping-MEKC.The determitatiom limit of the former is lower,so it is applicable to the determination of the paraquat concentration in serum before and after hemoperfusion.
2008, 25(9): 1073-1077
Abstract:
MoCl5 was found to activate the aromatic C-H bond,leading to in-situ C-C bond formation with high selectivity.A series of alkoxy-substituted aromatic compounds were coupled in para-position,in which it was not necessary to prepare the precursors:organometallics and ArX species.The present work provides a convenient method for the synthesis of pure symmetrical 4,4'-biaryls(e.g.,4,4'-dimethoxy-biphenyl,4,4'-diphenoxy-biphenyl,4,4'-dimethoxy-3,3'-dimethyl-biphenyl,2,3,2',3'-tetrahydro-[5,5']bibenzofuranyl,3,3'-dihydro-2,2'-dimethyl-[5,5']bibenzofuranyl,etc).Product structures were further verified by NMR and X-ray analysis.
MoCl5 was found to activate the aromatic C-H bond,leading to in-situ C-C bond formation with high selectivity.A series of alkoxy-substituted aromatic compounds were coupled in para-position,in which it was not necessary to prepare the precursors:organometallics and ArX species.The present work provides a convenient method for the synthesis of pure symmetrical 4,4'-biaryls(e.g.,4,4'-dimethoxy-biphenyl,4,4'-diphenoxy-biphenyl,4,4'-dimethoxy-3,3'-dimethyl-biphenyl,2,3,2',3'-tetrahydro-[5,5']bibenzofuranyl,3,3'-dihydro-2,2'-dimethyl-[5,5']bibenzofuranyl,etc).Product structures were further verified by NMR and X-ray analysis.
2008, 25(9): 1078-1081
Abstract:
Many complicated and different dynamic behaviors are accompanied in the synthetic process of mordenite zeolite.The fractal dimensionalities of X-ray diffraction curve during synthesizing mordenite zeolite were computed in the article.Based on the computed result,a nonlinear theoretical analysis was put forward.The analysis elaborated the nonlinear dynamic behavior in terms of order degree in chemical systems.
Many complicated and different dynamic behaviors are accompanied in the synthetic process of mordenite zeolite.The fractal dimensionalities of X-ray diffraction curve during synthesizing mordenite zeolite were computed in the article.Based on the computed result,a nonlinear theoretical analysis was put forward.The analysis elaborated the nonlinear dynamic behavior in terms of order degree in chemical systems.
2008, 25(9): 1082-1085
Abstract:
The effect of acidity on the synthesis of phenylbiguanide from the additive reaction of aniline with dicyandiamide was studied.Under low acidity conditions,the reaction rate was increased with the increase in acidity,and reaches the maximum value at pH=2.5.When the acidity was increased,the reaction rate was gradually decreased.The acid-base equilibration of aniline and dicyandiamide was calculated,it shows that when pH>2.5,the increasing of the concentration of protonated dicyandiamide made the dominant effect and increased the reaction rate.When pH<2.5,the aniline molecule integrated with H+,and the decreasing of nucleophile gave a dominant effect,which decreased the reaction rate.It also shows that dicyandiamide may hydrolyze when pH<3.5,and it is proved by IR,13C NMR and elemental analysis that the by product is guanylurea.
The effect of acidity on the synthesis of phenylbiguanide from the additive reaction of aniline with dicyandiamide was studied.Under low acidity conditions,the reaction rate was increased with the increase in acidity,and reaches the maximum value at pH=2.5.When the acidity was increased,the reaction rate was gradually decreased.The acid-base equilibration of aniline and dicyandiamide was calculated,it shows that when pH>2.5,the increasing of the concentration of protonated dicyandiamide made the dominant effect and increased the reaction rate.When pH<2.5,the aniline molecule integrated with H+,and the decreasing of nucleophile gave a dominant effect,which decreased the reaction rate.It also shows that dicyandiamide may hydrolyze when pH<3.5,and it is proved by IR,13C NMR and elemental analysis that the by product is guanylurea.
2008, 25(9): 1086-1089
Abstract:
The effect of surfactant on the abstersion of bronze in grinding process was studied,and different grinding assistants were tested.Many different surfactants were used in the grinding of the bronze powder and the abstersion effects of these assistants after the grind were analized in order to optimize the best formula of the grinding assistant.The results show that the washing efficiency and the quatity of the brozen powder can be improved effectively when the compound modifier composed of octadecanoic amime and stearic acid and OP-4 and water was used as the wet-grinding assistant;as for the abstersion effect,the OP-4 was better than OP-7 and OP-10 when OP series and octadecanoic amime were used;the effect of octadecanoic amine was better than that of osmotic reagent in ginding process and the grinding effect was better with stearic acid added than that without stearic acid.
The effect of surfactant on the abstersion of bronze in grinding process was studied,and different grinding assistants were tested.Many different surfactants were used in the grinding of the bronze powder and the abstersion effects of these assistants after the grind were analized in order to optimize the best formula of the grinding assistant.The results show that the washing efficiency and the quatity of the brozen powder can be improved effectively when the compound modifier composed of octadecanoic amime and stearic acid and OP-4 and water was used as the wet-grinding assistant;as for the abstersion effect,the OP-4 was better than OP-7 and OP-10 when OP series and octadecanoic amime were used;the effect of octadecanoic amine was better than that of osmotic reagent in ginding process and the grinding effect was better with stearic acid added than that without stearic acid.
2008, 25(9): 1090-1094
Abstract:
TAIC was epoxidized by H2O2 to prepare TGIC in the presence of a manganese salt and as the catalyst the chemical structure of TGIC was characterized with FT-IR and 1H NMR.The influences of the molar ratio of reactants,the amount of the catalyst,pH of the buffer solution and the reaction time on the yield were studied.When the molar ratio of TAIC to H2O2 was 1:15,the molar ratio of TAIC to manganese salt was 1:0.1,the buffer was NH4HCO3 solution in ethyl alcohol,the reaction time was 25 h and the reaction tem-perature was 25 ℃,the efficiency of H2O2 and the selectivity of TGIC were 15% and 69%,respectively.The reaction mechanism was also discussed in detail.Results show that the BAP systerm could provide reactive oxygen species to epoxidize carbon-carbon double bond,and the efficiency of H2O2 and selectivity of TGIC could be improved with the addition of Mn2+.
TAIC was epoxidized by H2O2 to prepare TGIC in the presence of a manganese salt and as the catalyst the chemical structure of TGIC was characterized with FT-IR and 1H NMR.The influences of the molar ratio of reactants,the amount of the catalyst,pH of the buffer solution and the reaction time on the yield were studied.When the molar ratio of TAIC to H2O2 was 1:15,the molar ratio of TAIC to manganese salt was 1:0.1,the buffer was NH4HCO3 solution in ethyl alcohol,the reaction time was 25 h and the reaction tem-perature was 25 ℃,the efficiency of H2O2 and the selectivity of TGIC were 15% and 69%,respectively.The reaction mechanism was also discussed in detail.Results show that the BAP systerm could provide reactive oxygen species to epoxidize carbon-carbon double bond,and the efficiency of H2O2 and selectivity of TGIC could be improved with the addition of Mn2+.
2008, 25(9): 1095-1100
Abstract:
A novel method for indirect determination of cefradine by extraction flotation of CuCSN with potassium nitrate-ammonium thiocyanate-water system was developed.At pH 4.0 to 6.0,in the existence of SCN-,the thiol group(-SH) of the degradation product of cefradine could reduce Cu(Ⅱ) to Cu(Ⅰ),and the resulting Cu(Ⅰ) could react with SCN- to form white emulsion precipitate CuSCN.In the presence of KNO3,this precipitate ascended and floated on the surface of water.The amount of cefradine can be determined by measuring the flotation yield of Cu(Ⅱ).When the amount of added Cu(Ⅱ) is 50 μg,the linear range is maintained in the range 0.3~12.0 mg/L with a correlation coefficient of 0.999 2.The detection limit is 0.25 mg/L.This proposed method was successfully applied to the determination of cefradine in capsules and the recovery of cefradine in urine and human plasma with satisfactory results.
A novel method for indirect determination of cefradine by extraction flotation of CuCSN with potassium nitrate-ammonium thiocyanate-water system was developed.At pH 4.0 to 6.0,in the existence of SCN-,the thiol group(-SH) of the degradation product of cefradine could reduce Cu(Ⅱ) to Cu(Ⅰ),and the resulting Cu(Ⅰ) could react with SCN- to form white emulsion precipitate CuSCN.In the presence of KNO3,this precipitate ascended and floated on the surface of water.The amount of cefradine can be determined by measuring the flotation yield of Cu(Ⅱ).When the amount of added Cu(Ⅱ) is 50 μg,the linear range is maintained in the range 0.3~12.0 mg/L with a correlation coefficient of 0.999 2.The detection limit is 0.25 mg/L.This proposed method was successfully applied to the determination of cefradine in capsules and the recovery of cefradine in urine and human plasma with satisfactory results.
2008, 25(9): 1101-1103
Abstract:
Ternary compounds Cu0.8Ag1.2S and Cu0.5Ag1.5Se with high crystallinity were prepared at room temperature in ethylenediamine solution.The procedure included the reduction of Ag2O and Cu2O by polyformaldehyde,followed by reaction of fresh-produced Ag,Cu with S or Se.The products were characterized with X-ray powder diffraction patterns,transmission electron microscope images and X-ray photoelectron spectra.A possible formation mechanism was proposed.
Ternary compounds Cu0.8Ag1.2S and Cu0.5Ag1.5Se with high crystallinity were prepared at room temperature in ethylenediamine solution.The procedure included the reduction of Ag2O and Cu2O by polyformaldehyde,followed by reaction of fresh-produced Ag,Cu with S or Se.The products were characterized with X-ray powder diffraction patterns,transmission electron microscope images and X-ray photoelectron spectra.A possible formation mechanism was proposed.
2008, 25(9): 1104-1106
Abstract:
Determination of lactic acid residue in L-lactide is necessary in controlling its purity and the quality in applications.In the presence of lactide,the method referred in GB2023-2003 to determine lactic acid content with back-titration by strong acid is improper;meanwhile the lactic acid content in lactide determined by sodium alkoxide titration reported previously appeared to be lower than the exact value.The two titration methods were correlated by a coefficent of P=1.228 and the method of quantitative determination of lactic acid in lactide by "titration-convert" was proposed.The result indicated the lactic acid content in lactide crystals and mother liquid decreased with recrystallization cycle.After 3 recrystallization cycles,the content of lactic acid was constant.The lactide met the requirement of polymerization with a lactic acid content of <1.0%,and polylactic acid with Mη up to 3×105 was obtained when the lactic acid content was <0.4%.
Determination of lactic acid residue in L-lactide is necessary in controlling its purity and the quality in applications.In the presence of lactide,the method referred in GB2023-2003 to determine lactic acid content with back-titration by strong acid is improper;meanwhile the lactic acid content in lactide determined by sodium alkoxide titration reported previously appeared to be lower than the exact value.The two titration methods were correlated by a coefficent of P=1.228 and the method of quantitative determination of lactic acid in lactide by "titration-convert" was proposed.The result indicated the lactic acid content in lactide crystals and mother liquid decreased with recrystallization cycle.After 3 recrystallization cycles,the content of lactic acid was constant.The lactide met the requirement of polymerization with a lactic acid content of <1.0%,and polylactic acid with Mη up to 3×105 was obtained when the lactic acid content was <0.4%.
2008, 25(9): 1107-1109
Abstract:
The critical micelle concentrations(cmc,1×10-4 mol/L) and the surface tension(γcmc,mN/m) of poly-alkylbenzene sulfonates synthesized in the laboratory were measured at 25 ℃.The cmc and γcmc values were(C12-5S) 3.889,32.69;(C14-3S) 1.000,31.40;(C14-5S) 1.173,30.21;(C14-7S) 3.720,28.55;(C16-5S) 1.016,29.96,respectively.The adsorption capacity Γmax,the saturated adsor-ption area Am,and the surfactant concentration needed in order to reduce surface tension by 20 mN/m(pc20) were calculated according to Gibbs adsorption equation.Their characteristics were explained based on molecular structure.
The critical micelle concentrations(cmc,1×10-4 mol/L) and the surface tension(γcmc,mN/m) of poly-alkylbenzene sulfonates synthesized in the laboratory were measured at 25 ℃.The cmc and γcmc values were(C12-5S) 3.889,32.69;(C14-3S) 1.000,31.40;(C14-5S) 1.173,30.21;(C14-7S) 3.720,28.55;(C16-5S) 1.016,29.96,respectively.The adsorption capacity Γmax,the saturated adsor-ption area Am,and the surfactant concentration needed in order to reduce surface tension by 20 mN/m(pc20) were calculated according to Gibbs adsorption equation.Their characteristics were explained based on molecular structure.
2008, 25(9): 1110-1112
Abstract:
The reaction system of Sb(Ⅲ)-KIO4-3-(2'-methylphenyl)-5-(2'-arsenoxyl-phenylazo) rhodanine was studied in the medium of potassium hydrogen phthalate-sodium hydroxide,where a new method of determination trace antimony with catalytic kinetic fluoremetry was established.λex/λem=308 nm/409 nm,the linear range is 1.67×10-11~0.01×10-6 g/mL,and the detection limit is 1.67×10-11 g/mL.The method was applied to determine the real samples with satisfactory results.
The reaction system of Sb(Ⅲ)-KIO4-3-(2'-methylphenyl)-5-(2'-arsenoxyl-phenylazo) rhodanine was studied in the medium of potassium hydrogen phthalate-sodium hydroxide,where a new method of determination trace antimony with catalytic kinetic fluoremetry was established.λex/λem=308 nm/409 nm,the linear range is 1.67×10-11~0.01×10-6 g/mL,and the detection limit is 1.67×10-11 g/mL.The method was applied to determine the real samples with satisfactory results.
2008, 25(9): 1113-1115
Abstract:
1,3-Dimethyl-2-substituted benzimidazolium salts can be easily prepared from phenylacetate or p-methoxybenzoic acid,o-phenylenediamine and methyl iodide via cyclization and quarternarization.Phenylacetaldehyde and p-methoxylbenzaldehyde were respectively prepared through the reduction-hydrolysis reaction of the corresponding 1,3-dimethyl-2-substituted benzimidazolium ioidide with sodium hydrogen telluride.A novel synthetic method for phenylacetaldehyde or p-methoxylbenzaldehyde from phenylacetate or p-methoxybenzoic acid via reduction-hydrolysis of benzimidazolium salt is presented.This synthetic route has mild reaction conditions and high product purities.The reaction mechanism is discussed.
1,3-Dimethyl-2-substituted benzimidazolium salts can be easily prepared from phenylacetate or p-methoxybenzoic acid,o-phenylenediamine and methyl iodide via cyclization and quarternarization.Phenylacetaldehyde and p-methoxylbenzaldehyde were respectively prepared through the reduction-hydrolysis reaction of the corresponding 1,3-dimethyl-2-substituted benzimidazolium ioidide with sodium hydrogen telluride.A novel synthetic method for phenylacetaldehyde or p-methoxylbenzaldehyde from phenylacetate or p-methoxybenzoic acid via reduction-hydrolysis of benzimidazolium salt is presented.This synthetic route has mild reaction conditions and high product purities.The reaction mechanism is discussed.
2008, 25(9): 1116-1118
Abstract:
Under acidic condition,the nitrogen in xanthinol nicotinate was protonated followed by its reaction with Cl4- anion to form an ion-complex,which was carried into a reversed micelle of cetyltrimethyla-mmonium chlorine containing luminol by chloroform,and the dissociated Cl4- reacted with luminol to produce an analytical chemiluminescence signal.In a certain concetration range,the CL intensity was proportional to the concentration of xanthinol nicotinate.Under the optimum conditions,the linear range was 0.01 to 15×10-6 g/mL,and the limit of detection was 0.4×10-9 g/mL with a relative standard deviation(n=11) of ca.1.26% for xanthinol nicotinate of 1.0×10-6 g/mL.The method is simple,sensitive and has been applied to determining the studied drug in injection successfully.
Under acidic condition,the nitrogen in xanthinol nicotinate was protonated followed by its reaction with Cl4- anion to form an ion-complex,which was carried into a reversed micelle of cetyltrimethyla-mmonium chlorine containing luminol by chloroform,and the dissociated Cl4- reacted with luminol to produce an analytical chemiluminescence signal.In a certain concetration range,the CL intensity was proportional to the concentration of xanthinol nicotinate.Under the optimum conditions,the linear range was 0.01 to 15×10-6 g/mL,and the limit of detection was 0.4×10-9 g/mL with a relative standard deviation(n=11) of ca.1.26% for xanthinol nicotinate of 1.0×10-6 g/mL.The method is simple,sensitive and has been applied to determining the studied drug in injection successfully.
2008, 25(9): 1119-1121
Abstract:
The scavenging effect of succinic acid chitosan complex with copper(Ⅱ) for superoxide anion radical and the reaction kinetics were studied by illumination method.The results showed that the scavenging rates of succinic acid chitosan complex with copper(Ⅱ) and natural superoxide dismutase(SOD) for superoxide anion radical were 90.55% and 93% respectively.The reaction rate constants of succinic acid chitosan complex with copper(Ⅱ) and superoxide anion radical were determined to be 1.26×109 L/(mol·s),1.11×109 L/(mol·s) and 4.98×108 L/(mol·s) respectively.
The scavenging effect of succinic acid chitosan complex with copper(Ⅱ) for superoxide anion radical and the reaction kinetics were studied by illumination method.The results showed that the scavenging rates of succinic acid chitosan complex with copper(Ⅱ) and natural superoxide dismutase(SOD) for superoxide anion radical were 90.55% and 93% respectively.The reaction rate constants of succinic acid chitosan complex with copper(Ⅱ) and superoxide anion radical were determined to be 1.26×109 L/(mol·s),1.11×109 L/(mol·s) and 4.98×108 L/(mol·s) respectively.
2008, 25(9): 1122-1124
Abstract:
A novel chiral polydentate ligand(1R,2R)-1,2-diphenyl-2-(2-methoxyethoxy)-ethoxyethyl picolinic acid ester was synthesized from trans-1,2-stilbene,tert-butyldimethylsilyl chloride and 1-(2-methoxy)-2-bromoethane through functional group protection,etherification,deprotction and substitution.The structure of the target product was characterized by NMR and LCMS and elemental analysis.
A novel chiral polydentate ligand(1R,2R)-1,2-diphenyl-2-(2-methoxyethoxy)-ethoxyethyl picolinic acid ester was synthesized from trans-1,2-stilbene,tert-butyldimethylsilyl chloride and 1-(2-methoxy)-2-bromoethane through functional group protection,etherification,deprotction and substitution.The structure of the target product was characterized by NMR and LCMS and elemental analysis.
