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2007 Volume 24 Issue 12
2007, 24(12): 1349-1353
Abstract:
The interactions of four indolizine-naphthoquinone(INQ) compounds with calf thymus DNA(CT-DNA) were studied by means of cyclic voltammetry and UV-Vis absorption spectroscopy techniques.A couple of strong redox peaks were observed in the cyclic voltammograms of the INQ compounds.Upon addition of CT-DNA,both the peak currents and the UV-Vis absorbance of the INQ compounds decreased and the peaks shifted to the positive direction with the increase of the CT-DNA concentration.The experimental results suggest that the interaction of the INQ with the CT-DNA belongs to the intercalative mode.In addition,the intercalative binding between the INQ and the CT-DNA is influenced by the conjugated system in the INQ.With longer conjugation,the π-π stack interaction between the INQ and the CT-DNA bases was strengthened and then the intercalative binding of the INQ with the CT-DNA was also strengthened.
The interactions of four indolizine-naphthoquinone(INQ) compounds with calf thymus DNA(CT-DNA) were studied by means of cyclic voltammetry and UV-Vis absorption spectroscopy techniques.A couple of strong redox peaks were observed in the cyclic voltammograms of the INQ compounds.Upon addition of CT-DNA,both the peak currents and the UV-Vis absorbance of the INQ compounds decreased and the peaks shifted to the positive direction with the increase of the CT-DNA concentration.The experimental results suggest that the interaction of the INQ with the CT-DNA belongs to the intercalative mode.In addition,the intercalative binding between the INQ and the CT-DNA is influenced by the conjugated system in the INQ.With longer conjugation,the π-π stack interaction between the INQ and the CT-DNA bases was strengthened and then the intercalative binding of the INQ with the CT-DNA was also strengthened.
2007, 24(12): 1354-1358
Abstract:
Cefamezin-sodium(CEZ) alginate microcapsules were prepared by emulsifying Cefamezin sodium alginate PBS buffer solution into hexane/Span-85 phase and then single-coacervated by calcium chloride.The in vitro drug-release tests of the microcapsules were studied and the inhibition toward Staphylococcus,Hay Bacillus and Escherichia coli by their extravasates respectively were also performed via pervasion method.The results show that the microcapsules were flaxen clathrate,anomalistic granules with diameters 1~15 μm observed by means of Scan Electronic Microscopy(SEM).The entrapment efficiency and drug loading capacity for CEZ reached(80.42±0.26)% and(35.68±2.03)% respectively.In artificial gastric and intestinal fluid,the cyst wall made of sodium alginate displays palliative effect.Extravasates from the microcapsules show good antibacterial effect on Staphylococcus and Hay Bacillus,but weak effect on Escherichia coli.It is disclosed that the microcapsules made of sodium alginate is a good candidate as clinical sustained delivery system for CEZ.
Cefamezin-sodium(CEZ) alginate microcapsules were prepared by emulsifying Cefamezin sodium alginate PBS buffer solution into hexane/Span-85 phase and then single-coacervated by calcium chloride.The in vitro drug-release tests of the microcapsules were studied and the inhibition toward Staphylococcus,Hay Bacillus and Escherichia coli by their extravasates respectively were also performed via pervasion method.The results show that the microcapsules were flaxen clathrate,anomalistic granules with diameters 1~15 μm observed by means of Scan Electronic Microscopy(SEM).The entrapment efficiency and drug loading capacity for CEZ reached(80.42±0.26)% and(35.68±2.03)% respectively.In artificial gastric and intestinal fluid,the cyst wall made of sodium alginate displays palliative effect.Extravasates from the microcapsules show good antibacterial effect on Staphylococcus and Hay Bacillus,but weak effect on Escherichia coli.It is disclosed that the microcapsules made of sodium alginate is a good candidate as clinical sustained delivery system for CEZ.
2007, 24(12): 1359-1363
Abstract:
A series of m-phenylene based copolymers containing a small fraction of thiophene derivative moieties poly[5-(2-ethylhexyloxy)-1,3-phenylene-co-(2,5-diphenylene-4-yl-thiophene)](PmP-DPT) was synthesized by means of Yamamoto coupling reaction.These copolymers were characterized by UV-Vis absorption spectra and photoluminescent spectra.Polymer light-emitting diodes(PLED) were fabricated to investigate the electroluminescent properties.It was found that the thiophene derivative moieties became the new emitter via efficient energy transfer from the poly(m-phenylene) segments.With the increase of its feed ratio,the photoluminescence spectra showed red-shift.CIE(0.17,0.13) can be obtained for PmP-DPT1 devices with a quantum efficiency of 0.47%,while CIE(0.21,0.36) can be obtained for PmP-DPT10 devices with a quantum efficiency of 2.59%.
A series of m-phenylene based copolymers containing a small fraction of thiophene derivative moieties poly[5-(2-ethylhexyloxy)-1,3-phenylene-co-(2,5-diphenylene-4-yl-thiophene)](PmP-DPT) was synthesized by means of Yamamoto coupling reaction.These copolymers were characterized by UV-Vis absorption spectra and photoluminescent spectra.Polymer light-emitting diodes(PLED) were fabricated to investigate the electroluminescent properties.It was found that the thiophene derivative moieties became the new emitter via efficient energy transfer from the poly(m-phenylene) segments.With the increase of its feed ratio,the photoluminescence spectra showed red-shift.CIE(0.17,0.13) can be obtained for PmP-DPT1 devices with a quantum efficiency of 0.47%,while CIE(0.21,0.36) can be obtained for PmP-DPT10 devices with a quantum efficiency of 2.59%.
2007, 24(12): 1364-1367
Abstract:
Principle component analysis(PCA),in combination with learning vector quantization(LVQ) neural network,was applied to extract information features from remote sensing Fourier transform infrared spectroscopic(RS-FTIR) data,and rapid qualitative analysis of eight components in atmosphere was demonstrated using this PCA-LVQ approach.Compared with LVQ neural network and BP-ANN,PCA-LVQ can process data more efficiently,with a much faster computation speed and a higher prediction accuracy.The classification precision was as high as 91.7%.The high prediction accuracy and fast computation speed of PCA-LVQ can meet the needs of real-time and on-line monitoring of atmospheric toxic species via FTIR.
Principle component analysis(PCA),in combination with learning vector quantization(LVQ) neural network,was applied to extract information features from remote sensing Fourier transform infrared spectroscopic(RS-FTIR) data,and rapid qualitative analysis of eight components in atmosphere was demonstrated using this PCA-LVQ approach.Compared with LVQ neural network and BP-ANN,PCA-LVQ can process data more efficiently,with a much faster computation speed and a higher prediction accuracy.The classification precision was as high as 91.7%.The high prediction accuracy and fast computation speed of PCA-LVQ can meet the needs of real-time and on-line monitoring of atmospheric toxic species via FTIR.
2007, 24(12): 1368-1373
Abstract:
A new organotin oxo cluster compound was synthesized from the reaction of 6-hydroxyl-2-phenyl-3-pyridazinone and di-n-butyltin oxide.The compound was characterized by elemental analysis,IR and X-ray single crystal diffraction. The compound shows a centro-symmetric dimer structure mode belonging to the triclinic space group P1 with a=1.221 75(13) nm,b=1.267 90(13) nm,c=1.345 33(14) nm,α=87.168 0(10)°,β=672.265 0(10)°,γ=87.261 0(10)°,V=1.981 4(4) nm3,Z=1,Dc=1.435 g/cm3,μ(MoKα)=0.870 0,F(000)=868.The identification results show that it has a ladder structure with centric symmetry,in which the tin atom is five-coordinated,forming a distorted trigonal bipyramid.The compound can catalyze the transesterification between acetoacetic ester and methanol with a yield of 88%;it also catalyzes the transesterification between methylmalonate and ethanol with a yield of 90%.However,it is less effective to catalyze the acetalation between cyclohexanone and propanetriol with a yield of no more than 22%.
A new organotin oxo cluster compound was synthesized from the reaction of 6-hydroxyl-2-phenyl-3-pyridazinone and di-n-butyltin oxide.The compound was characterized by elemental analysis,IR and X-ray single crystal diffraction. The compound shows a centro-symmetric dimer structure mode belonging to the triclinic space group P1 with a=1.221 75(13) nm,b=1.267 90(13) nm,c=1.345 33(14) nm,α=87.168 0(10)°,β=672.265 0(10)°,γ=87.261 0(10)°,V=1.981 4(4) nm3,Z=1,Dc=1.435 g/cm3,μ(MoKα)=0.870 0,F(000)=868.The identification results show that it has a ladder structure with centric symmetry,in which the tin atom is five-coordinated,forming a distorted trigonal bipyramid.The compound can catalyze the transesterification between acetoacetic ester and methanol with a yield of 88%;it also catalyzes the transesterification between methylmalonate and ethanol with a yield of 90%.However,it is less effective to catalyze the acetalation between cyclohexanone and propanetriol with a yield of no more than 22%.
2007, 24(12): 1374-1377
Abstract:
A series of niobic acids at different calcination temperatures was prepared.BET,acid amount and distribution of acidity of niobic acid catalysts were investigated.The effects of all kinds of factors,just like calcination temperature of niobic acid catalysts,nitration reaction time,nitration reaction temperature,recovered catalyst,acetic anhydride and concentration of nitric acid were studied by gas chromatography(GC).The nitration of toluene was carried out in the presence of acetic anhydride with CCl4 as solvent,95% nitric acid as nitrating reagent,and niobic acid calcinated at 300℃ for 3 h as catalyst for 60 min at 40℃.A yield of 99.3% of mononitoluene with an ortho-para-isomer ratio of 1.26 was obtained,which is greatly below 1.67 with sulfonitric acid as catalyst.The catalyst could be re-utilized up to five times with little decrease in activity.It is a clean nitrated reaction catalyst in vast prospects of application.
A series of niobic acids at different calcination temperatures was prepared.BET,acid amount and distribution of acidity of niobic acid catalysts were investigated.The effects of all kinds of factors,just like calcination temperature of niobic acid catalysts,nitration reaction time,nitration reaction temperature,recovered catalyst,acetic anhydride and concentration of nitric acid were studied by gas chromatography(GC).The nitration of toluene was carried out in the presence of acetic anhydride with CCl4 as solvent,95% nitric acid as nitrating reagent,and niobic acid calcinated at 300℃ for 3 h as catalyst for 60 min at 40℃.A yield of 99.3% of mononitoluene with an ortho-para-isomer ratio of 1.26 was obtained,which is greatly below 1.67 with sulfonitric acid as catalyst.The catalyst could be re-utilized up to five times with little decrease in activity.It is a clean nitrated reaction catalyst in vast prospects of application.
2007, 24(12): 1378-1382
Abstract:
Highly dispersed Pt-CeO2/C electrode was prepared by mixing ceria sol with Pt/C powder,and electro-oxidation of methanol was studied in sulfuric acid electrolyte at room temperature on Pt-CeO2/C catalyst.It was found that the Pt-CeO2/C catalyst exhibited a higher catalytic activity towards methanol electro-oxidation than Pt /C catalyst.Transmission electron microscopy(TEM) and X-ray diffraction(XRD) analyses indicated the formation of homogenous mixtures of ceria and Pt nanometer particles with size of around 3~4 nm on carbon support.Electro-oxidation of methanol was studied on the Pt-CeO2/C electrodes employing various amounts of CeO2 in sulfuric acid electrolyte at room temperature.The electrochemical characterization by cyclic voltammetry(CV) and chronoamperometry demonstrated that the catalytic activity of the Pt-CeO2/C was highest when the mass ratio of Pt:CeO2 was 1:1,where the current density for electro-oxidation of methanol was 0.112 A/cm2.
Highly dispersed Pt-CeO2/C electrode was prepared by mixing ceria sol with Pt/C powder,and electro-oxidation of methanol was studied in sulfuric acid electrolyte at room temperature on Pt-CeO2/C catalyst.It was found that the Pt-CeO2/C catalyst exhibited a higher catalytic activity towards methanol electro-oxidation than Pt /C catalyst.Transmission electron microscopy(TEM) and X-ray diffraction(XRD) analyses indicated the formation of homogenous mixtures of ceria and Pt nanometer particles with size of around 3~4 nm on carbon support.Electro-oxidation of methanol was studied on the Pt-CeO2/C electrodes employing various amounts of CeO2 in sulfuric acid electrolyte at room temperature.The electrochemical characterization by cyclic voltammetry(CV) and chronoamperometry demonstrated that the catalytic activity of the Pt-CeO2/C was highest when the mass ratio of Pt:CeO2 was 1:1,where the current density for electro-oxidation of methanol was 0.112 A/cm2.
2007, 24(12): 1383-1387
Abstract:
This paper reports the absorption-release properties of sodium polyacrylate(PAANa).The results show that urea had no effect on the ratio of absor ption(WAR),while NH4Cl greatly reduced the WAR,and the higher the NH4Cl concentration,the smaller the WAR.PAANa has the for urea of different concentrations,the WAR of the PAANa was 370 g/g.When the NH4Cl concentration was 5,10,15,and 20 g/L,the WAR was 82,62,56,and 55,respectively.The distribution coefficent(mkd) of urea was about 1,while mkd was 1 in NH4Cl,and decreased when the NH4Cl concentration increased.PAANa showed enrichment effect for NH4+ but not for urea.The absorption capacity for urea was about 10 times of that for NH4+.PAANa exhi-bited slow-release property for the absorbed urea and NH4+.When the PAANa was dipped in water 4 times(24 h each),the accumulative release rate of urea and NH4+ was about 80%and 60% respectively.FT-IR spectroscopy indicated that there was an ion-exchange reaction between the NH4+ and the cation in PAANa.
This paper reports the absorption-release properties of sodium polyacrylate(PAANa).The results show that urea had no effect on the ratio of absor ption(WAR),while NH4Cl greatly reduced the WAR,and the higher the NH4Cl concentration,the smaller the WAR.PAANa has the for urea of different concentrations,the WAR of the PAANa was 370 g/g.When the NH4Cl concentration was 5,10,15,and 20 g/L,the WAR was 82,62,56,and 55,respectively.The distribution coefficent(mkd) of urea was about 1,while mkd was 1 in NH4Cl,and decreased when the NH4Cl concentration increased.PAANa showed enrichment effect for NH4+ but not for urea.The absorption capacity for urea was about 10 times of that for NH4+.PAANa exhi-bited slow-release property for the absorbed urea and NH4+.When the PAANa was dipped in water 4 times(24 h each),the accumulative release rate of urea and NH4+ was about 80%and 60% respectively.FT-IR spectroscopy indicated that there was an ion-exchange reaction between the NH4+ and the cation in PAANa.
2007, 24(12): 1388-1391
Abstract:
Hybrid peroxotungsten and peroxomolybdenum with 1,10-phenanthroline(Phen) H2M2O3(O2)4·2Phen(M=W,Mo) were synthesized and characterized by elemental analysis,gravimetry,titration,TG/DSC,IR and UV-Vis spectroscopy,which supplied new catalysts for the green synthesis of adipic acid.Their catalytic activities for the oxidation of cyclohexene,cyclohexanol and cyclohexanone by H2O2 to adipic acid were evaluated in the absence of organic solvent and phase-transfer agent.It was found that peroxotungsten catalyst exhibited a high activity,while peroxomolybdenum was not active.In the case of H2M2O3(O2)4·2Phen·H2O,the isolated yield of adipic acid could reach 89.9%,53.5% and 64.8% using cyclohexene,cyclohexanol or cyclohexanone as the substrate respectively when the reaction was carried out at 90℃ for 12 h and the ratio of substrate:catalyst:H2O2 was 100:1.2:440.
Hybrid peroxotungsten and peroxomolybdenum with 1,10-phenanthroline(Phen) H2M2O3(O2)4·2Phen(M=W,Mo) were synthesized and characterized by elemental analysis,gravimetry,titration,TG/DSC,IR and UV-Vis spectroscopy,which supplied new catalysts for the green synthesis of adipic acid.Their catalytic activities for the oxidation of cyclohexene,cyclohexanol and cyclohexanone by H2O2 to adipic acid were evaluated in the absence of organic solvent and phase-transfer agent.It was found that peroxotungsten catalyst exhibited a high activity,while peroxomolybdenum was not active.In the case of H2M2O3(O2)4·2Phen·H2O,the isolated yield of adipic acid could reach 89.9%,53.5% and 64.8% using cyclohexene,cyclohexanol or cyclohexanone as the substrate respectively when the reaction was carried out at 90℃ for 12 h and the ratio of substrate:catalyst:H2O2 was 100:1.2:440.
2007, 24(12): 1392-1395
Abstract:
To prepare starch-based polyanion or to incorporate carboxyl groups onto the backbone of starch,radical copolymerization of starch and maleic acid in an aqueous medium was performed with Fenton's reagent as the redox initiator.The effect of reaction conditions such as the initiator concentration,reaction temperature and reaction time on the percent content of carboxyl groups(PCCG) of the derivative was investigated.It was found that the PCCG of the derivative could be 31.32% when 3 g starch and 3 g maleic acid were initiated by both 0.009 85 mol/L Fe2+ and 4.412 mol/L H2O2 and copolymerized at 60℃ for 5 h.In addition,PCCG of the derivative could be controlled between 2.7%~31.5% by adjusting the initiator concentration or the reaction temperature.The structure of the derivative was verified by FTIR.X-ray diffraction and TGA results showed that both the crystallinity and 20%-decomposed temperature of the carboxylic derivative decreased with the increase of PCCG.
To prepare starch-based polyanion or to incorporate carboxyl groups onto the backbone of starch,radical copolymerization of starch and maleic acid in an aqueous medium was performed with Fenton's reagent as the redox initiator.The effect of reaction conditions such as the initiator concentration,reaction temperature and reaction time on the percent content of carboxyl groups(PCCG) of the derivative was investigated.It was found that the PCCG of the derivative could be 31.32% when 3 g starch and 3 g maleic acid were initiated by both 0.009 85 mol/L Fe2+ and 4.412 mol/L H2O2 and copolymerized at 60℃ for 5 h.In addition,PCCG of the derivative could be controlled between 2.7%~31.5% by adjusting the initiator concentration or the reaction temperature.The structure of the derivative was verified by FTIR.X-ray diffraction and TGA results showed that both the crystallinity and 20%-decomposed temperature of the carboxylic derivative decreased with the increase of PCCG.
2007, 24(12): 1396-1400
Abstract:
An organic-inorganic complex [Co(phen)3]4[VW12O40](OH)5 was synthesized from NH4VO3,NH2VO4·2H2O,CoCl2 2H2O,C12H8N12 H2O(phenanthroline) by hydrothermal method and characterized by elemental analysis,IR and X-ray diffraction.The X-ray crystallography indicates that the title compound crystallized in a triclinic lattice,P1 space group,with a=1.638 9(3) nm,b=1.774 4(4) nm,c=18.275(4) nm,α=61.04(3)°,β=78.49(3)°,γ=64.64(3)°,V=4.201 8(15) nm3,Z=1,R1=0.083 6,wR2=0.222 8.Structural analysis reveals that the molecule of the title compound is composed of four chiral [Co(phen)3]2+ coordination cations,one independent [VW12O40]3- anion and five dissociative OH-anions.The four coordination cations are located around the anion parallelogram-symmetrically by interaction of electrostatic force and the [VW12O40]3- anion is located in the center of the parallelogram.The molecules form a 3D network structure through π-π stacking interaction.
An organic-inorganic complex [Co(phen)3]4[VW12O40](OH)5 was synthesized from NH4VO3,NH2VO4·2H2O,CoCl2 2H2O,C12H8N12 H2O(phenanthroline) by hydrothermal method and characterized by elemental analysis,IR and X-ray diffraction.The X-ray crystallography indicates that the title compound crystallized in a triclinic lattice,P1 space group,with a=1.638 9(3) nm,b=1.774 4(4) nm,c=18.275(4) nm,α=61.04(3)°,β=78.49(3)°,γ=64.64(3)°,V=4.201 8(15) nm3,Z=1,R1=0.083 6,wR2=0.222 8.Structural analysis reveals that the molecule of the title compound is composed of four chiral [Co(phen)3]2+ coordination cations,one independent [VW12O40]3- anion and five dissociative OH-anions.The four coordination cations are located around the anion parallelogram-symmetrically by interaction of electrostatic force and the [VW12O40]3- anion is located in the center of the parallelogram.The molecules form a 3D network structure through π-π stacking interaction.
2007, 24(12): 1401-1404
Abstract:
With TiCl4,ammonia and surfactant as the raw material,the dispersion emulsion of mix-crystal nanometric TiO2 was obtained by 2-step hydrolyzation method under constant pressure.Morphologies,compositions and structures of the samples were characterized.The results show that the dispersity of emulsion is good and the average diameter of particles is about 15 nm.Its bactericidal properties to some bacteria and epiphytes are strong under daylight lamp irradiation.The killing rate to Gram negative bacterium(Staphylo-coccus aureus and Bacillus subtilis) is 100%,in addition,killing activity of it to Gram positive bacterium(Escherichia coli) is very high.It has a clear antibacterial circle of about 20 mm in diameter toward epiphytes such as Aspergillus niger,Aspergillus flavus and Candida albicans etc.
With TiCl4,ammonia and surfactant as the raw material,the dispersion emulsion of mix-crystal nanometric TiO2 was obtained by 2-step hydrolyzation method under constant pressure.Morphologies,compositions and structures of the samples were characterized.The results show that the dispersity of emulsion is good and the average diameter of particles is about 15 nm.Its bactericidal properties to some bacteria and epiphytes are strong under daylight lamp irradiation.The killing rate to Gram negative bacterium(Staphylo-coccus aureus and Bacillus subtilis) is 100%,in addition,killing activity of it to Gram positive bacterium(Escherichia coli) is very high.It has a clear antibacterial circle of about 20 mm in diameter toward epiphytes such as Aspergillus niger,Aspergillus flavus and Candida albicans etc.
2007, 24(12): 1405-1408
Abstract:
Kinetic studies were carried out on the CaWO4 thin films prepared by the chemical bath deposition(CBD).Kinetic data based on Avrami-Erofeev equation were founded at different deposing temperatures(40~80℃) and pH values(8~12).It indicated that the experimental temperature and the pH value of solution could significantly affect the reaction velocity constant k.With the temperature rising,the reaction rate constant k increased,and the film growth was prone to spontaneous nucleation.Meanwhile,the higher the solution pH value was,the slower the film growed.The pH value controls the reaction process by influencing the stability of complex Ca-EDTA.From these kinetic studies we can clarify the dependence of the growth of thin films on experimental parameters,providing a theoretical view to control the process of the deposition.
Kinetic studies were carried out on the CaWO4 thin films prepared by the chemical bath deposition(CBD).Kinetic data based on Avrami-Erofeev equation were founded at different deposing temperatures(40~80℃) and pH values(8~12).It indicated that the experimental temperature and the pH value of solution could significantly affect the reaction velocity constant k.With the temperature rising,the reaction rate constant k increased,and the film growth was prone to spontaneous nucleation.Meanwhile,the higher the solution pH value was,the slower the film growed.The pH value controls the reaction process by influencing the stability of complex Ca-EDTA.From these kinetic studies we can clarify the dependence of the growth of thin films on experimental parameters,providing a theoretical view to control the process of the deposition.
2007, 24(12): 1409-1413
Abstract:
Perovskite-type oxide La2CuO4 was synthesized by the glycine-nitrate process(GNP).The thick film type oxygen-sensing element was fabricated and its oxygen-sensing properties were investigated.The sensitivity of the thick-film La2CuO4 decreased with the increase of the measurement temperature because the oxygen-sensing properties of La2CuO4 was mainly determined by the surface carrier concentration.Oxygen adsorbed on the surface of the La2CuO4 thick films desorbed rapidly with the increase of the measurement temperature,which resulted in decrease of the surface carrier concentration.The highest sensitivity of the thick-film La2CuO4 obtained at 400℃ was 29.6,much higher than that of the sintered bulk ones.The corresponding response time of the thick-film sensors to the change of oxygen partial pressure was about 4 seconds at 400℃.
Perovskite-type oxide La2CuO4 was synthesized by the glycine-nitrate process(GNP).The thick film type oxygen-sensing element was fabricated and its oxygen-sensing properties were investigated.The sensitivity of the thick-film La2CuO4 decreased with the increase of the measurement temperature because the oxygen-sensing properties of La2CuO4 was mainly determined by the surface carrier concentration.Oxygen adsorbed on the surface of the La2CuO4 thick films desorbed rapidly with the increase of the measurement temperature,which resulted in decrease of the surface carrier concentration.The highest sensitivity of the thick-film La2CuO4 obtained at 400℃ was 29.6,much higher than that of the sintered bulk ones.The corresponding response time of the thick-film sensors to the change of oxygen partial pressure was about 4 seconds at 400℃.
Improvement of Antibacterial Activity of Activated Carbon Supported Silver Modified with Citric Acid
2007, 24(12): 1414-1417
Abstract:
Specific surface area of activated carbon(AC) treated with citric acid solution was determined by N2 adsorption technique,and the adsorption and distribution of silver on the AC were investigated by AAS,SEM,XRD.The antibacterial activities of the AC supported silver(AC/Ag) against Staphylococcus aureus(S.aureus) and Escherichia coli(E.coli) were investigated.The results show that the citric acid modification reduced the number of cracks and cavities on the activated carbon,reducing the specific surface area of AC by about 24%,but the surface area increased after silver was leaded.The citric acid modification created more surface groups that improved the adsorption of silver ion by 25%. Silver granules became denser and smaller and more uniform after the modification.This modified AC/Ag catalyst possesses a stronger antibacterial activity for the growing of E.coli and S.aureus than the unmodified AC/Ag catalyst,and it has a stronger inhibitory effect on the growing of S.aureus than E.coli.Additionally,the citric acid modification is advantageous to the preparation of effective AC/Ag catalysts and the extraction of silver from solutions.
Specific surface area of activated carbon(AC) treated with citric acid solution was determined by N2 adsorption technique,and the adsorption and distribution of silver on the AC were investigated by AAS,SEM,XRD.The antibacterial activities of the AC supported silver(AC/Ag) against Staphylococcus aureus(S.aureus) and Escherichia coli(E.coli) were investigated.The results show that the citric acid modification reduced the number of cracks and cavities on the activated carbon,reducing the specific surface area of AC by about 24%,but the surface area increased after silver was leaded.The citric acid modification created more surface groups that improved the adsorption of silver ion by 25%. Silver granules became denser and smaller and more uniform after the modification.This modified AC/Ag catalyst possesses a stronger antibacterial activity for the growing of E.coli and S.aureus than the unmodified AC/Ag catalyst,and it has a stronger inhibitory effect on the growing of S.aureus than E.coli.Additionally,the citric acid modification is advantageous to the preparation of effective AC/Ag catalysts and the extraction of silver from solutions.
2007, 24(12): 1418-1423
Abstract:
Nanometer-size iron oxides were respectively prepared by homogeneous precipitation,sol-gel phase transfer,and sol-gel evaporation processes,and the preparation conditions were studied and the powders were characterized.Scanning electron microscopy showed that the average grain size was between 100~ 300 nm.The adsorption of As(Ⅴ) on the nanometer-size iron oxides prepared by the different processes under different conditions was compared experimentally.The results indicated that the nanometer-size iron oxides can lower the arsenic concentration to below 0.01 mg/L from 2 mg/L in solution at pH between 4.0 and 6.0.The maximal adsorption capacity of the iron oxides prepared by sol-gel evaporation process was 30.96,30.58 and 17.06 mg/g when the pH was 3,7,and 10,respectively,and the adsorption capacity of the nanometer-size iron oxide thus prepared was greater than that of the other nanometer-size oxides and common block iron oxides.Its adsorption isotherm can be fitted by Langmuir adsorption equation with a correlation coefficient R2 of >0.95.
Nanometer-size iron oxides were respectively prepared by homogeneous precipitation,sol-gel phase transfer,and sol-gel evaporation processes,and the preparation conditions were studied and the powders were characterized.Scanning electron microscopy showed that the average grain size was between 100~ 300 nm.The adsorption of As(Ⅴ) on the nanometer-size iron oxides prepared by the different processes under different conditions was compared experimentally.The results indicated that the nanometer-size iron oxides can lower the arsenic concentration to below 0.01 mg/L from 2 mg/L in solution at pH between 4.0 and 6.0.The maximal adsorption capacity of the iron oxides prepared by sol-gel evaporation process was 30.96,30.58 and 17.06 mg/g when the pH was 3,7,and 10,respectively,and the adsorption capacity of the nanometer-size iron oxide thus prepared was greater than that of the other nanometer-size oxides and common block iron oxides.Its adsorption isotherm can be fitted by Langmuir adsorption equation with a correlation coefficient R2 of >0.95.
2007, 24(12): 1424-1427
Abstract:
SPE water electrolysis was applied to H/D isotope separation.The separation factors(α) of H/D isotopes at IrRu/Nafion117/PbAg,IrRu/Nafion117/TiNi3,IrRu/Nafion117/Ni,and C/Nafion112/Pt-TiO2 MEA electrodes at 40℃ and 90×10-3 A/cm2 were about 4.49,3.48,3.14,and 4.53,respectively.Further study using IrRu/Nafion117/PbAg electrode was carried out.The separation factors using this electrode at 40℃ and current density i of 90×10-3,150×10-3,and 300×10-3 A/cm2 were 4.49,4.65,and 5.46,respectively,and were 3.76,4.11 and 4.38 at 60℃ with these current densities.When the temperature was 70℃ and i=90×10-3 A/cm-2,the separation factor was 3.53.The temperature dependence of α was found to follow the equation of lnα=0.816×(10-3/T)-1.112,and the calculated activation energy-ΔHa was about 6 778 J/mol in the temperature range of 40~70℃.The results show that the separation factor increased with the increase of current density,but decreased with the increase of temperature.The isotopic effect on the H/D transport in Nafion membrane was also discussed.
SPE water electrolysis was applied to H/D isotope separation.The separation factors(α) of H/D isotopes at IrRu/Nafion117/PbAg,IrRu/Nafion117/TiNi3,IrRu/Nafion117/Ni,and C/Nafion112/Pt-TiO2 MEA electrodes at 40℃ and 90×10-3 A/cm2 were about 4.49,3.48,3.14,and 4.53,respectively.Further study using IrRu/Nafion117/PbAg electrode was carried out.The separation factors using this electrode at 40℃ and current density i of 90×10-3,150×10-3,and 300×10-3 A/cm2 were 4.49,4.65,and 5.46,respectively,and were 3.76,4.11 and 4.38 at 60℃ with these current densities.When the temperature was 70℃ and i=90×10-3 A/cm-2,the separation factor was 3.53.The temperature dependence of α was found to follow the equation of lnα=0.816×(10-3/T)-1.112,and the calculated activation energy-ΔHa was about 6 778 J/mol in the temperature range of 40~70℃.The results show that the separation factor increased with the increase of current density,but decreased with the increase of temperature.The isotopic effect on the H/D transport in Nafion membrane was also discussed.
2007, 24(12): 1428-1432
Abstract:
CdSe/CdS nanocrystals(NCs) was prepared and modified with 11-mercaptoundecanoic acid [HS-(CH2)10-COOH] in aqueous solution.The functionalized NCs were characterized via transmission electron microscopy(TEM),ultraviolet-visible(UV-Vis) spectroscopy,and photoluminescence(PL) spectroscopy.The results demonstrate that CdSe/CdS NCs are dispersed homogeneously in aqueous solution and well protected from the environmental oxygen.They can be used as a new fluorescence probe for lysozyme,which is simple,rapid and specific.Under the optimum conditions,linear relationship is found between the relative fluorescence intensity and the lysozyme concentration in a range of 0~44×10-6 g/mL for CdSe/CdS NCs,the linear equation is ΔF=73+41.9c(106c(lys)/(g·mL-1).The detection limit of CdSe/CdS NCs is 2.33×10-7 g/mL.The proposed method has been applied to the determination of lysozyme in egg white.
CdSe/CdS nanocrystals(NCs) was prepared and modified with 11-mercaptoundecanoic acid [HS-(CH2)10-COOH] in aqueous solution.The functionalized NCs were characterized via transmission electron microscopy(TEM),ultraviolet-visible(UV-Vis) spectroscopy,and photoluminescence(PL) spectroscopy.The results demonstrate that CdSe/CdS NCs are dispersed homogeneously in aqueous solution and well protected from the environmental oxygen.They can be used as a new fluorescence probe for lysozyme,which is simple,rapid and specific.Under the optimum conditions,linear relationship is found between the relative fluorescence intensity and the lysozyme concentration in a range of 0~44×10-6 g/mL for CdSe/CdS NCs,the linear equation is ΔF=73+41.9c(106c(lys)/(g·mL-1).The detection limit of CdSe/CdS NCs is 2.33×10-7 g/mL.The proposed method has been applied to the determination of lysozyme in egg white.
2007, 24(12): 1433-1438
Abstract:
Electrochemical behavior of tryptophan at MWNTs modified glassy carbon electrode(MWNTs/GC) was studied.It was demonstrated that MWNTs/GC electrode could effectively catalyze Trp oxidation,where the anodic peak potential shifted to negative by 128 mV,and the oxidation peak current greatly increased to 32 times that of glassy carbon electrode.Scanned in 1.0 mol/L H2SO4,the electrodes can be renovated to eliminate the influence of oxidation product adsorbed on the electrode surface.The current of the MWNTs/GC electrode was stabilized by closed-circuit way in the buffer solution(pH=2.2) including 1.0×10-4 mol/L Trp in 2 min.The effects of pH on the potential and the current were studied,which revealed that equal number of protons and electrons were involved in the oxidation process,and the current reached the maximum at pH=2.2.The linear relationship between the current and the scan rate revealed that the electrode process was surface-controlled.In the environment below 45℃, the current increased gradually with increasing temperature.In the range of 16 to 35℃,linear dependence of the current on the temperature was observed with a temperature coefficient of 0.695 μA/℃,which indicated that the detection result was weakly interfered by the temperature of the surroundings.The relationship between the current and the concentration was studied by LSV.The peak current was linearly proportional to the concentration of Trp in the range of 1.00×10-6 mol/L to 1.00×10-4 mol/L.The detection limit was 1.82×10-7 mol/L(S/N=3).The MWNTs/GC electrode showed good sensitivity,selectivity and stability.After exposure in atmosphere for 7 days,the oxidation current of Trp at MWNTs/GC electrode still retained 98% of the original value.
Electrochemical behavior of tryptophan at MWNTs modified glassy carbon electrode(MWNTs/GC) was studied.It was demonstrated that MWNTs/GC electrode could effectively catalyze Trp oxidation,where the anodic peak potential shifted to negative by 128 mV,and the oxidation peak current greatly increased to 32 times that of glassy carbon electrode.Scanned in 1.0 mol/L H2SO4,the electrodes can be renovated to eliminate the influence of oxidation product adsorbed on the electrode surface.The current of the MWNTs/GC electrode was stabilized by closed-circuit way in the buffer solution(pH=2.2) including 1.0×10-4 mol/L Trp in 2 min.The effects of pH on the potential and the current were studied,which revealed that equal number of protons and electrons were involved in the oxidation process,and the current reached the maximum at pH=2.2.The linear relationship between the current and the scan rate revealed that the electrode process was surface-controlled.In the environment below 45℃, the current increased gradually with increasing temperature.In the range of 16 to 35℃,linear dependence of the current on the temperature was observed with a temperature coefficient of 0.695 μA/℃,which indicated that the detection result was weakly interfered by the temperature of the surroundings.The relationship between the current and the concentration was studied by LSV.The peak current was linearly proportional to the concentration of Trp in the range of 1.00×10-6 mol/L to 1.00×10-4 mol/L.The detection limit was 1.82×10-7 mol/L(S/N=3).The MWNTs/GC electrode showed good sensitivity,selectivity and stability.After exposure in atmosphere for 7 days,the oxidation current of Trp at MWNTs/GC electrode still retained 98% of the original value.
2007, 24(12): 1439-1442
Abstract:
To study the relationship between the "tail" structure and the characteristics of Gemini surfactants,a new gemini surfactant CsH2s-α,ω-bis(dehydroabietylhydroxypropyltetramethylethyldiammonium Chloride),here s=2,has been synthesized.Dehydrogenated rosin as hydrophobic "tails" in the structure.The affections of reacttants ratio,reaction temperature and time on the yield of aimed compound have been discussed.The structure of aimed gemini surfactant was confirmed by IR,MS and elemental analysis.Properties of the surfactant were investigated via surface tension.The critical micell concentration(cmc) of the synthesized surfactant was 1.0×10-4 mol/L and the minimum surface tension was 34.9 mN/m.The results show that the two big "tail" make the synthesized surfactant form micelle more easily.
To study the relationship between the "tail" structure and the characteristics of Gemini surfactants,a new gemini surfactant CsH2s-α,ω-bis(dehydroabietylhydroxypropyltetramethylethyldiammonium Chloride),here s=2,has been synthesized.Dehydrogenated rosin as hydrophobic "tails" in the structure.The affections of reacttants ratio,reaction temperature and time on the yield of aimed compound have been discussed.The structure of aimed gemini surfactant was confirmed by IR,MS and elemental analysis.Properties of the surfactant were investigated via surface tension.The critical micell concentration(cmc) of the synthesized surfactant was 1.0×10-4 mol/L and the minimum surface tension was 34.9 mN/m.The results show that the two big "tail" make the synthesized surfactant form micelle more easily.
2007, 24(12): 1443-1447
Abstract:
A series of Cu catalysts supported on MgO/Sepiolite composite carriers were prepared by precipitation method combined with impregnation method and used for dehydrogenation of cyclohexanol.The catalysts were characterized by means of N2 adsorption,X-ray diffraction(XRD),Infrared spectroscopy(IR),NH3 temperature programmed desorption(NH3-TPD),and temperature programmed reduction(TPR),respec-tively.The results show that the addition of sepiolite facilitated the increase of the specific surface area of the catalysts,but when the fraction of the sepiolite in the carrier was too high,the acidity of the catalyst and the form of the Cu species would be influenced,which lead to decrease of the activity and selectivity of the catalysts.When the mass ratio of Sepiolite in the composite carrier was up to 40%,the catalyst exhibit an excellent catalytic activity and selectivity.
A series of Cu catalysts supported on MgO/Sepiolite composite carriers were prepared by precipitation method combined with impregnation method and used for dehydrogenation of cyclohexanol.The catalysts were characterized by means of N2 adsorption,X-ray diffraction(XRD),Infrared spectroscopy(IR),NH3 temperature programmed desorption(NH3-TPD),and temperature programmed reduction(TPR),respec-tively.The results show that the addition of sepiolite facilitated the increase of the specific surface area of the catalysts,but when the fraction of the sepiolite in the carrier was too high,the acidity of the catalyst and the form of the Cu species would be influenced,which lead to decrease of the activity and selectivity of the catalysts.When the mass ratio of Sepiolite in the composite carrier was up to 40%,the catalyst exhibit an excellent catalytic activity and selectivity.
2007, 24(12): 1448-1451
Abstract:
Physicochemical properties of Fucoidan extracted by different ways were determined and compared.For the Fucoidan from alcohol precipitation,the total sugar content was(76.00±9.00)%,the Fucoidan content was(35.60±4.20)%,the vitriolic radical was(11.33±0.47)%,and the weight averaged molecular mass(Mw) and the number averaged molecular mass(Mn) were 3.42×104 and 1.21×104.For the Fucoidan from macromolecule electrolyte precipitation,the total sugar content was(70.00±11.00)%,the Fucoidan was (35.15±2.85)%,the vitriolic radical was(10.80±0.58)%,and the Mw and Mn were 1.15×105 and 5.88×104.The content of macromolecule electrolyte residue was(0.12±0.038)% in the crude Fucoidan,and(0.022±0.022)% in the purified Fucoidan.So it has been proved that alcohol precipitation method is better than the other.But the macromolecule electrolyte precipitation method has its advantages.For example,it is a simple process with lower cost and more suitable for industrialization.
Physicochemical properties of Fucoidan extracted by different ways were determined and compared.For the Fucoidan from alcohol precipitation,the total sugar content was(76.00±9.00)%,the Fucoidan content was(35.60±4.20)%,the vitriolic radical was(11.33±0.47)%,and the weight averaged molecular mass(Mw) and the number averaged molecular mass(Mn) were 3.42×104 and 1.21×104.For the Fucoidan from macromolecule electrolyte precipitation,the total sugar content was(70.00±11.00)%,the Fucoidan was (35.15±2.85)%,the vitriolic radical was(10.80±0.58)%,and the Mw and Mn were 1.15×105 and 5.88×104.The content of macromolecule electrolyte residue was(0.12±0.038)% in the crude Fucoidan,and(0.022±0.022)% in the purified Fucoidan.So it has been proved that alcohol precipitation method is better than the other.But the macromolecule electrolyte precipitation method has its advantages.For example,it is a simple process with lower cost and more suitable for industrialization.
2007, 24(12): 1452-1454
Abstract:
The contents of luteolin,quercetin and kaempferol in Eupatorium Odoratum Linn were determined with RP-HPLC/PAD method.The chromatographic conditions were chromatographic column HiQ sil C18W,detection wavelength 254 nm for quercetin, 360 nm for luteolin and kaempferol,temperature 30℃,mobile phase CH3OH-H2O-H3PO4(50:49.8:0.2,volume ratio), 1 mL/min flow rate,10 μL injection volume.Analysis sample was prepared by ultrasonic extraction from Eupatorium Odoratum Linn with the following conditions:85% ethanol solution as solvent,ratio of liquid to solid 10:1(mL/g),extraction time 1 h.The results showed good linearity(R2>0.999 0) for the three flavonoids over a range of 0.01×10-3~0.10×10-3 g/mL,and the average recovery yields were 99.601 7%,99.032 6%,and 99.450 8%,respectively.The relative standard deviation(RSD) was less than 2%.The method is simple and efficient for the determination of luteolin,quercetin and kaempferol from Eupatorium odortum Linn with high accuracy.
The contents of luteolin,quercetin and kaempferol in Eupatorium Odoratum Linn were determined with RP-HPLC/PAD method.The chromatographic conditions were chromatographic column HiQ sil C18W,detection wavelength 254 nm for quercetin, 360 nm for luteolin and kaempferol,temperature 30℃,mobile phase CH3OH-H2O-H3PO4(50:49.8:0.2,volume ratio), 1 mL/min flow rate,10 μL injection volume.Analysis sample was prepared by ultrasonic extraction from Eupatorium Odoratum Linn with the following conditions:85% ethanol solution as solvent,ratio of liquid to solid 10:1(mL/g),extraction time 1 h.The results showed good linearity(R2>0.999 0) for the three flavonoids over a range of 0.01×10-3~0.10×10-3 g/mL,and the average recovery yields were 99.601 7%,99.032 6%,and 99.450 8%,respectively.The relative standard deviation(RSD) was less than 2%.The method is simple and efficient for the determination of luteolin,quercetin and kaempferol from Eupatorium odortum Linn with high accuracy.
2007, 24(12): 1455-1457
Abstract:
A convenient,efficient pinacol coupling of carbonyl compounds mediated by zinc in good yields was carried out in water in the presence of NH4Cl and tiny Bu4NCl or Bu4PBr.It was highly effective to enhance yields of pinacol by adding a small amount of Bu4NCl or Bu4PBr,the yield of pinacol was increased from 53% to 87%,and it was strongly affected by the steric environment surrounding the carbonyl group.The pinacol coupling of aromatic aldehydes was also completed with high yields under above conditions.However,the diastereoselectivities of pinacols were not effective,and the ketones and most aliphatic aldehydes appeared to be inert under the same reaction conditions.
A convenient,efficient pinacol coupling of carbonyl compounds mediated by zinc in good yields was carried out in water in the presence of NH4Cl and tiny Bu4NCl or Bu4PBr.It was highly effective to enhance yields of pinacol by adding a small amount of Bu4NCl or Bu4PBr,the yield of pinacol was increased from 53% to 87%,and it was strongly affected by the steric environment surrounding the carbonyl group.The pinacol coupling of aromatic aldehydes was also completed with high yields under above conditions.However,the diastereoselectivities of pinacols were not effective,and the ketones and most aliphatic aldehydes appeared to be inert under the same reaction conditions.
2007, 24(12): 1458-1460
Abstract:
Via direct polycondensation method,a thermotropic liquid crystalline polyamide with a high moleculor weight(ηinh=1.063 dL/g) was prepared from the novel diacid PEG3 and a commercial aromatic diamine.The thermal and the deliquescent properties of the polyamide were studied.The result shows that the melting point(Tm=307.8℃) of the polyamide was reduced effectively because of the introduction of flexible chain,which also favored the formation of liquid crystalline phase.Moreover,the phenyl rings introduced distributed evenly the rigidity of the polyamide,which maintained the heat-resistant characteristic of the polyamide,and increased the stability of the liquid crystalline phase(ΔT=Ti-Tm=66.1℃),and favored the application of the liquid crystalline polymer.TGA showed good thermal stability of the poliamide,where the temperature for a mass loss of 5% was above 400℃.The solvent-resistance of the polyamide was good.It was not solvable in nonpolar solvents,and was soluble partly in strong polar,pure solvents,and soluble in saliferous complex solvents(LiCl or CaCl2).
Via direct polycondensation method,a thermotropic liquid crystalline polyamide with a high moleculor weight(ηinh=1.063 dL/g) was prepared from the novel diacid PEG3 and a commercial aromatic diamine.The thermal and the deliquescent properties of the polyamide were studied.The result shows that the melting point(Tm=307.8℃) of the polyamide was reduced effectively because of the introduction of flexible chain,which also favored the formation of liquid crystalline phase.Moreover,the phenyl rings introduced distributed evenly the rigidity of the polyamide,which maintained the heat-resistant characteristic of the polyamide,and increased the stability of the liquid crystalline phase(ΔT=Ti-Tm=66.1℃),and favored the application of the liquid crystalline polymer.TGA showed good thermal stability of the poliamide,where the temperature for a mass loss of 5% was above 400℃.The solvent-resistance of the polyamide was good.It was not solvable in nonpolar solvents,and was soluble partly in strong polar,pure solvents,and soluble in saliferous complex solvents(LiCl or CaCl2).
2007, 24(12): 1461-1463
Abstract:
Furoin was synthesized from furol with VB1 as the catalyst,which was then reacted with acetyl chloride,lauroyl chloride,benzoyl chloride,α-furoyl chloride and 3-α-furyl acryloyl chloride,respectively;corresponding monoester compounds of furoin were synthesized in THF in the presence of sodium hydroxide under reflux.The yields of compounds 1,2,3,4,and 5 based on furoin were 99.3%,96.5%,98.0%,99.4% and 98.7%,respectively.By characterization with elementary analysis,Mass spectrum and 1H NMR,the structures of the target products were characterized by elemental analysis,MS and 1H NMR.
Furoin was synthesized from furol with VB1 as the catalyst,which was then reacted with acetyl chloride,lauroyl chloride,benzoyl chloride,α-furoyl chloride and 3-α-furyl acryloyl chloride,respectively;corresponding monoester compounds of furoin were synthesized in THF in the presence of sodium hydroxide under reflux.The yields of compounds 1,2,3,4,and 5 based on furoin were 99.3%,96.5%,98.0%,99.4% and 98.7%,respectively.By characterization with elementary analysis,Mass spectrum and 1H NMR,the structures of the target products were characterized by elemental analysis,MS and 1H NMR.
2007, 24(12): 1464-1466
Abstract:
The equilibrium concentration of Ca2+ and Mg2+ in a calcium and magnesium silicate(CaO·mSiO2,MgO·mSiO2,m is the modulus) saturated solution was determined with an ICPS-1000IV high frequency plasma emission spectrograph at a certain temperature.The solubility product of calcium and magnesium silicate was calculated,and the effects of temperature and water glass modulus on the solubility product were also studied in this article.The results indicate that the solubility product of calcium silicate is smaller than that of the magnesium silicate.When the temperature is 30℃ and the water glass modulus is 3.29,the solubility product of calcium silicate is 1.14×10-8,while the solubility product of magnesium silicate is 2.29×10-5.At the same temperature,the solubility product of the corresponding calcium and magnesium silicate decreases with the increase in the water class modulus.Since the increase in the modulus causes the silicate ionic diameter to become bigger,the calcium and magnesium silicate crystal is easier to precipitate,which makes the solubility product of both calcium and magnesium silicate decrease.
The equilibrium concentration of Ca2+ and Mg2+ in a calcium and magnesium silicate(CaO·mSiO2,MgO·mSiO2,m is the modulus) saturated solution was determined with an ICPS-1000IV high frequency plasma emission spectrograph at a certain temperature.The solubility product of calcium and magnesium silicate was calculated,and the effects of temperature and water glass modulus on the solubility product were also studied in this article.The results indicate that the solubility product of calcium silicate is smaller than that of the magnesium silicate.When the temperature is 30℃ and the water glass modulus is 3.29,the solubility product of calcium silicate is 1.14×10-8,while the solubility product of magnesium silicate is 2.29×10-5.At the same temperature,the solubility product of the corresponding calcium and magnesium silicate decreases with the increase in the water class modulus.Since the increase in the modulus causes the silicate ionic diameter to become bigger,the calcium and magnesium silicate crystal is easier to precipitate,which makes the solubility product of both calcium and magnesium silicate decrease.
2007, 24(12): 1467-1469
Abstract:
The RRS intensity was enhanced greatly when Co(Ⅱ) reacted with PAN to form cation chelate complex which further reacted with SDBS to form an ion-association complex in a pH=9.0 Tris-HCl buffer solution,and the RRS intensity was linearly related to the concentration of Co(Ⅱ) in a range of 0~5.0×10-7 g/mL(r=0.998 0).Based on this fact,a sensitive and simple RRS method for the determination of Cobalt(Ⅱ) was proposed with a detection limit of 2.68×10-9 g/mL.This method was applied to the determination of cobalt in human hair,tea leaves and vitamin B12 with a recovery of 97.83%~105.4%.This method has the advantages of high sensitivity and simplicity,and it was applied to the determination of Co(Ⅱ) in same biological samples with satisfactory results.
The RRS intensity was enhanced greatly when Co(Ⅱ) reacted with PAN to form cation chelate complex which further reacted with SDBS to form an ion-association complex in a pH=9.0 Tris-HCl buffer solution,and the RRS intensity was linearly related to the concentration of Co(Ⅱ) in a range of 0~5.0×10-7 g/mL(r=0.998 0).Based on this fact,a sensitive and simple RRS method for the determination of Cobalt(Ⅱ) was proposed with a detection limit of 2.68×10-9 g/mL.This method was applied to the determination of cobalt in human hair,tea leaves and vitamin B12 with a recovery of 97.83%~105.4%.This method has the advantages of high sensitivity and simplicity,and it was applied to the determination of Co(Ⅱ) in same biological samples with satisfactory results.
2007, 24(12): 1470-1472
Abstract:
5-Hydroxy-1,4-naphthoquinone was synthesized in one pot by dropping methanol solution of 1,5-dihydroxy naphthalene to peroxyacetic acid formed from acetic anhydride and hydrogen peroxide without H2SO4 with a yield of 68%.The product was purified by recrystallization from benzene,and its structure was confirmed by HPLC,UV,FTIR,1H NMR and 13C NMR.The reaction conditions,such as the ratio of the reactants,reaction temperature and reaction time,were optimized.The optimum molar ratio was 1:4:8 of 1,5-dihydroxy naphthalene,acetic anhydride and hydrogen peroxide.The reaction temperature was 40~60℃ and the reaction time 5.5 h.The results suggest that the one-pot-method is an efficient and convenient synthesis approach of juglone without using H2SO4 and purification of peroxyacetic acid by vacuum distillation.
5-Hydroxy-1,4-naphthoquinone was synthesized in one pot by dropping methanol solution of 1,5-dihydroxy naphthalene to peroxyacetic acid formed from acetic anhydride and hydrogen peroxide without H2SO4 with a yield of 68%.The product was purified by recrystallization from benzene,and its structure was confirmed by HPLC,UV,FTIR,1H NMR and 13C NMR.The reaction conditions,such as the ratio of the reactants,reaction temperature and reaction time,were optimized.The optimum molar ratio was 1:4:8 of 1,5-dihydroxy naphthalene,acetic anhydride and hydrogen peroxide.The reaction temperature was 40~60℃ and the reaction time 5.5 h.The results suggest that the one-pot-method is an efficient and convenient synthesis approach of juglone without using H2SO4 and purification of peroxyacetic acid by vacuum distillation.
