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2011 Volume 28 Issue 3
2011, 28(3): 245-253
doi: 10.3724/SP.J.1095.2011.00268
Abstract:
In this paper, we mainly discussed the involved mechanism in single electron transfer living radical polymerization. The types of catalysts, ligands, solvents as well as monomers suitable for such kinds of polymerizations have been also addressed in detail. In addition, the perspectives of this single electron transfer living radical polymerization was highlighted.
In this paper, we mainly discussed the involved mechanism in single electron transfer living radical polymerization. The types of catalysts, ligands, solvents as well as monomers suitable for such kinds of polymerizations have been also addressed in detail. In addition, the perspectives of this single electron transfer living radical polymerization was highlighted.
2011, 28(3): 254-257
doi: 10.3724/SP.J.1095.2011.00151
Abstract:
This paper developed a washing-extraction method to remove the residual Cu-ion from the triblock copolymer of poly(methyl methacrylate) -b-poly(L-lactic acid)-b-poly(methyl methacrylate) (PMMA-b-PLLA-b-PMMA) prepared via atom transfer radical polymerization (ATRP). The result is that, when taking dichloromethane(DCM) as the solvent and water or acid as the extractant, the rate of removing Cu-ion can reach as much as 99% and the yield of the block copolymerization was more than 80% followed by washing and extracting 5 times. Compared with other methods, the washing-extraction method can not only save lots of organic solvent, but is also simple and effective. In addition, the washing-extraction method is a green technology, which might be used in the industry.
This paper developed a washing-extraction method to remove the residual Cu-ion from the triblock copolymer of poly(methyl methacrylate) -b-poly(L-lactic acid)-b-poly(methyl methacrylate) (PMMA-b-PLLA-b-PMMA) prepared via atom transfer radical polymerization (ATRP). The result is that, when taking dichloromethane(DCM) as the solvent and water or acid as the extractant, the rate of removing Cu-ion can reach as much as 99% and the yield of the block copolymerization was more than 80% followed by washing and extracting 5 times. Compared with other methods, the washing-extraction method can not only save lots of organic solvent, but is also simple and effective. In addition, the washing-extraction method is a green technology, which might be used in the industry.
2011, 28(3): 258-262
doi: 10.3724/SP.J.1095.2011.00332
Abstract:
We monitored the imidization process of poly(amic acid) synthesized from pyromellitic dianhidride and 4, 4'-oxydianiline, and analyzed the IR bands of the poly(amic acid) and the polyimide after thermal imidization using variable temperature FTIR spectroscopy in transmission mode. We investigated peak assignments of the poly(amic acid) and the polyimide and found——COO- and——NH2+ in the system. The C=O symmetrical and asymmetrical stretching vibrations in——COO- locate at 1607 and 1406 cm-1 respectively, NH2+ stretching vibration locate at 3200, 3133, 2938, 2880, 2820, 2610 cm-1. According to the identified IR absorption peaks of ——COO- and ——NH2+, we proposed the mechanism of the imidization process of poly(amic acid) that during the imidization H+ from COOH of the poly(amic acid) can move to NH of the poly(amic acid) and form ——COO- and NH2+, then the intermediate cyclodehydrates to polyimide at last.
We monitored the imidization process of poly(amic acid) synthesized from pyromellitic dianhidride and 4, 4'-oxydianiline, and analyzed the IR bands of the poly(amic acid) and the polyimide after thermal imidization using variable temperature FTIR spectroscopy in transmission mode. We investigated peak assignments of the poly(amic acid) and the polyimide and found——COO- and——NH2+ in the system. The C=O symmetrical and asymmetrical stretching vibrations in——COO- locate at 1607 and 1406 cm-1 respectively, NH2+ stretching vibration locate at 3200, 3133, 2938, 2880, 2820, 2610 cm-1. According to the identified IR absorption peaks of ——COO- and ——NH2+, we proposed the mechanism of the imidization process of poly(amic acid) that during the imidization H+ from COOH of the poly(amic acid) can move to NH of the poly(amic acid) and form ——COO- and NH2+, then the intermediate cyclodehydrates to polyimide at last.
2011, 28(3): 263-266
doi: 10.3724/SP.J.1095.2011.00327
Abstract:
The N-alkylations of methyl 3-indoleglyoxylate and indole-3-acetonitrile were carried out using alkyl halides or sulfonates as electrophiles in the presence of bases and six new N-alkylation products of indole derivatives were prepared. The influences of the structures of indole derivatives and electrophiles, the solvents and bases on the alkylations have been studied. The N-alkylation of methyl 3-indoleglyoxylate with a strong electron-withdrawing group could be conducted using weak base Cs2CO3 in mild reaction condition and in 93% yields while a strong base such as NaH must be used when indole-3-acetonitrile with a weak electronwithdrawing group was used as reactant in the N-alkylation.
The N-alkylations of methyl 3-indoleglyoxylate and indole-3-acetonitrile were carried out using alkyl halides or sulfonates as electrophiles in the presence of bases and six new N-alkylation products of indole derivatives were prepared. The influences of the structures of indole derivatives and electrophiles, the solvents and bases on the alkylations have been studied. The N-alkylation of methyl 3-indoleglyoxylate with a strong electron-withdrawing group could be conducted using weak base Cs2CO3 in mild reaction condition and in 93% yields while a strong base such as NaH must be used when indole-3-acetonitrile with a weak electronwithdrawing group was used as reactant in the N-alkylation.
2011, 28(3): 267-271
doi: 10.3724/SP.J.1095.2011.00271
Abstract:
CaO-ZrO2 nanoparticles with CaO molar fraction ranging from 10% to 50% were prepared by the sol-gel method and their catalytic performances were evaluated in biodiesel production from flaxseed oil; XRD, CO2-TPD, and TEM were employed for the catalyst characterization. The results indicate that when CaO molar fraction was lower than 30%, the samples form CaO-ZrO2 homogeneous solid solution, which possesses good thermal stability and the grain diameter is 10~20 nm. The experimental results show that the highest catalytic activity can be achieved when CaO molar fraction was 30%. The yield of conversion could reach 93.2% when the reaction conditions were optimized for the transesterification of flaxseed oil. The dosage (mass ratio) of catalyst to oil was 2.5%, the reaction temperature and time were 65℃ and 2 h respectively, and the molar ratio of methanol to oil is 12:1.
CaO-ZrO2 nanoparticles with CaO molar fraction ranging from 10% to 50% were prepared by the sol-gel method and their catalytic performances were evaluated in biodiesel production from flaxseed oil; XRD, CO2-TPD, and TEM were employed for the catalyst characterization. The results indicate that when CaO molar fraction was lower than 30%, the samples form CaO-ZrO2 homogeneous solid solution, which possesses good thermal stability and the grain diameter is 10~20 nm. The experimental results show that the highest catalytic activity can be achieved when CaO molar fraction was 30%. The yield of conversion could reach 93.2% when the reaction conditions were optimized for the transesterification of flaxseed oil. The dosage (mass ratio) of catalyst to oil was 2.5%, the reaction temperature and time were 65℃ and 2 h respectively, and the molar ratio of methanol to oil is 12:1.
2011, 28(3): 272-277
doi: 10.3724/SP.J.1095.2011.00380
Abstract:
A fullerene-phosphine metal complex C60Pt(dpppe) was synthesized by ligand substitution method with bis (diphenylphosphino) pentane and C60 as ligand and platinum as central metal. The product was completely characterized by MS, elemental analysis, UV-Vis, IR and XPS. At the same time, the redox properties of the product were studied by cyclic voltammetry. The results showed that the reduction potential was negatively shifted after C60 coordination with platinum. In addition, the energy level structure of the compound was determined by electronic spectrum, and energies of the highest occupied orbital and the lowest unoccupied orbital were 5.635 eV and 3.815 eV. In the meantime, the photovoltaic effect of the complex was determined in the photochemistry cell. The results showed that the fullerene-phosphine metal complex exhibited high photoelectric conversion property, especially under the conditions of BQ/H2Q redox couples, and a maximum value of 358 mV was obtained for the photovoltage when the film thickness was 1~2 μm.
A fullerene-phosphine metal complex C60Pt(dpppe) was synthesized by ligand substitution method with bis (diphenylphosphino) pentane and C60 as ligand and platinum as central metal. The product was completely characterized by MS, elemental analysis, UV-Vis, IR and XPS. At the same time, the redox properties of the product were studied by cyclic voltammetry. The results showed that the reduction potential was negatively shifted after C60 coordination with platinum. In addition, the energy level structure of the compound was determined by electronic spectrum, and energies of the highest occupied orbital and the lowest unoccupied orbital were 5.635 eV and 3.815 eV. In the meantime, the photovoltaic effect of the complex was determined in the photochemistry cell. The results showed that the fullerene-phosphine metal complex exhibited high photoelectric conversion property, especially under the conditions of BQ/H2Q redox couples, and a maximum value of 358 mV was obtained for the photovoltage when the film thickness was 1~2 μm.
2011, 28(3): 278-283
doi: 10.3724/SP.J.1095.2011.00313
Abstract:
Chlorine-doped titanium pillared montmorillonite(Cl-TM) was prepared by the sol-gel technique in order to improve the photocatalytic activity. X-ray diffraction(XRD), scanning electron microscope(SEM), energy dispersive spectroscopy (EDS), UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), photoluminescence spectrometer(PLS), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared spectroscopy(FT-IR), N2 adsorption-desorption (BET) were used to characterize the products. The results show that the products had typical anatase phase while keeping the pillared structure of montmorillonite. The presence of montmorillonite can inhibite the phase transformation of titania from anatase to rutile. In addition, Chlorine-doped sample can reduce the band gap energy of TiO2 from 3.19 eV to 3.14 eV and therefore extend the light response of TiO2 to visible light region. XPS data imply that chlorine existed in the TiO2 crystal lattice as an anion. Furthermore, the photocatalytic degradation of PNA by Cl-TM indicates that the activity was significantly affected by chlorine-doped amount, and the optimized content is 6% (molar ratio of Cl to Ti).
Chlorine-doped titanium pillared montmorillonite(Cl-TM) was prepared by the sol-gel technique in order to improve the photocatalytic activity. X-ray diffraction(XRD), scanning electron microscope(SEM), energy dispersive spectroscopy (EDS), UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), photoluminescence spectrometer(PLS), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared spectroscopy(FT-IR), N2 adsorption-desorption (BET) were used to characterize the products. The results show that the products had typical anatase phase while keeping the pillared structure of montmorillonite. The presence of montmorillonite can inhibite the phase transformation of titania from anatase to rutile. In addition, Chlorine-doped sample can reduce the band gap energy of TiO2 from 3.19 eV to 3.14 eV and therefore extend the light response of TiO2 to visible light region. XPS data imply that chlorine existed in the TiO2 crystal lattice as an anion. Furthermore, the photocatalytic degradation of PNA by Cl-TM indicates that the activity was significantly affected by chlorine-doped amount, and the optimized content is 6% (molar ratio of Cl to Ti).
2011, 28(3): 284-289
doi: 10.3724/SP.J.1095.2011.00345
Abstract:
A novel compound, (C5H7N2) 3 (AsMo12O40) ·3C5H6N2·2H2O, has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, IR, UV/Vis and TG-DTA. Using catalytic elimination reaction of acetone as a model reaction, the catalytic performance of the title compound has been tested. The results indicate that the structure of the title compound consists of[AsMo12O40]3- heteropolyoxoanion,[C5H7N2]+ cations,[C5H6N2] molecules and water molecules. The compound crystallizes in the monoclinic, space group P21/n, a=1.33820(12) nm, b=2.2542(2) nm, c=1.9848(2) nm, β=100.27(3) °, V=5.8912(10) nm3, Z=4, Rgt(F)=0.0590, wRref(F2)=0.1882. The compound has a good catalytic activity for the elimination of acetone. When the initial concentration of acetone is 1.3 g/m3 in the air with a flow velocity of 4.5 mL/min, the acetone is completely eliminated at 160℃ over 0.20 g of the title compound.
A novel compound, (C5H7N2) 3 (AsMo12O40) ·3C5H6N2·2H2O, has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, IR, UV/Vis and TG-DTA. Using catalytic elimination reaction of acetone as a model reaction, the catalytic performance of the title compound has been tested. The results indicate that the structure of the title compound consists of[AsMo12O40]3- heteropolyoxoanion,[C5H7N2]+ cations,[C5H6N2] molecules and water molecules. The compound crystallizes in the monoclinic, space group P21/n, a=1.33820(12) nm, b=2.2542(2) nm, c=1.9848(2) nm, β=100.27(3) °, V=5.8912(10) nm3, Z=4, Rgt(F)=0.0590, wRref(F2)=0.1882. The compound has a good catalytic activity for the elimination of acetone. When the initial concentration of acetone is 1.3 g/m3 in the air with a flow velocity of 4.5 mL/min, the acetone is completely eliminated at 160℃ over 0.20 g of the title compound.
2011, 28(3): 290-296
doi: 10.3724/SP.J.1095.2011.00282
Abstract:
A tetranuclear cluster crystal[Cu4 (Pyims) 4] ·4H2O·4CH3OH was synthesized from the reaction between cupric perchlorate and 4-(3-pyridyl) -2-mercapto imidazole(PyimsH) in methanol medium at room temperature, and characterized by elemental analysis, IR and single-crystal X-ray diffraction. The results reveal that the compound belongs to tetragonal system with space group I41/a. The cell parameters are a=1.44432(12) nm, b=1.44432(12) nm, c=2.2119(3) nm, α=90°, β=90°, γ=90°, V=4.6142(8) nm3, Z=4, Dc=1.669 Mg/m3, Mr=1159.26, R1=0.0761, wR2=0.1839(I >2σ). In the cluster molecule, the Cu44+ core takes a distorted tetrahedron configuration. Four Pyims- ligands coordinate with cuprous ions by N atom of imidazole and S atom of sulfhydryl, and two cuprous ions are linked by one S atom t. The cluster molecules are held together via the N(3)----H(7)——C(7) hydrogen-bondings, which result in a three-dimensional network geometry. The electrochemical behavior of the title cluster was studied by cyclic voltammetry. Through simple dropcoating method, the title cluster was used to modify the surface of glassy carbon electrode(GCE) to fabricate an amperometric sensor. It has been found that the peak potential of the oxygen reduction at the modified electrode is positively shifted from -0.55 V to -0.247 V in pH=5.9 phosphate buffer solution. The obvious decrease of the over potential indicates that the sensor has high electrocatalytic activity to oxygen reduction, which suggests that the title cluster complex can be used as the anode material for fuel cells.
A tetranuclear cluster crystal[Cu4 (Pyims) 4] ·4H2O·4CH3OH was synthesized from the reaction between cupric perchlorate and 4-(3-pyridyl) -2-mercapto imidazole(PyimsH) in methanol medium at room temperature, and characterized by elemental analysis, IR and single-crystal X-ray diffraction. The results reveal that the compound belongs to tetragonal system with space group I41/a. The cell parameters are a=1.44432(12) nm, b=1.44432(12) nm, c=2.2119(3) nm, α=90°, β=90°, γ=90°, V=4.6142(8) nm3, Z=4, Dc=1.669 Mg/m3, Mr=1159.26, R1=0.0761, wR2=0.1839(I >2σ). In the cluster molecule, the Cu44+ core takes a distorted tetrahedron configuration. Four Pyims- ligands coordinate with cuprous ions by N atom of imidazole and S atom of sulfhydryl, and two cuprous ions are linked by one S atom t. The cluster molecules are held together via the N(3)----H(7)——C(7) hydrogen-bondings, which result in a three-dimensional network geometry. The electrochemical behavior of the title cluster was studied by cyclic voltammetry. Through simple dropcoating method, the title cluster was used to modify the surface of glassy carbon electrode(GCE) to fabricate an amperometric sensor. It has been found that the peak potential of the oxygen reduction at the modified electrode is positively shifted from -0.55 V to -0.247 V in pH=5.9 phosphate buffer solution. The obvious decrease of the over potential indicates that the sensor has high electrocatalytic activity to oxygen reduction, which suggests that the title cluster complex can be used as the anode material for fuel cells.
2011, 28(3): 297-301
doi: 10.3724/SP.J.1095.2011.00288
Abstract:
One-dimensional nanotubular MnO2/PPy/PANI ternary composites were prepared by in-situ chemical oxidative polymerization of pyrrole in the host of MnO2 and PANI, using methyl orange/FeCl3 as a reactive self-degraded soft-template. Their morphologies and microstructures were characterized by X-ray diffraction(XRD) analysis, infrared analysis, transmission electron microscopy(TEM). The electrochemical properties of the ternary composites for electrochemical capacitors were investigated by cyclic voltammogram (CV), galvanostatic charge/discharge tests. The results indicated that the ternary composites were characterized with greater specific capacitance than the binary composite of MnO2/PPy due to the synergy effect of PPy, PANI, and MnO2. Hollow tube-like structure of PPy with high surface area might enhance the specific capacitance. The materials had also given a good charge-discharge cycle performance and a maximum specific capacitance of 458.4 F/g was obtained.
One-dimensional nanotubular MnO2/PPy/PANI ternary composites were prepared by in-situ chemical oxidative polymerization of pyrrole in the host of MnO2 and PANI, using methyl orange/FeCl3 as a reactive self-degraded soft-template. Their morphologies and microstructures were characterized by X-ray diffraction(XRD) analysis, infrared analysis, transmission electron microscopy(TEM). The electrochemical properties of the ternary composites for electrochemical capacitors were investigated by cyclic voltammogram (CV), galvanostatic charge/discharge tests. The results indicated that the ternary composites were characterized with greater specific capacitance than the binary composite of MnO2/PPy due to the synergy effect of PPy, PANI, and MnO2. Hollow tube-like structure of PPy with high surface area might enhance the specific capacitance. The materials had also given a good charge-discharge cycle performance and a maximum specific capacitance of 458.4 F/g was obtained.
2011, 28(3): 302-307
doi: 10.3724/SP.J.1095.2011.00311
Abstract:
The polyaniline/polysulfone (PAN/PSF) composite film modified electrodes doped with cerium oxide were prepared by electropolymerization, and then Pt particles were deposited into this composite film to obtain the Pt modified cerium oxide/polyaniline/polysulfone (Pt-CeO2/PAN/PSF) electrodes. Their morphology and chemical component were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS), respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were applied to investigate the electrocatalytic activity of the electrode for methanol oxidation. The results show that the composite film has a bi-layer structure with asymmetrical pores, and platinum and cerium oxide particles are uniformly dispersed in the modified film electrodes. The average size of particles is about 80 nm. The electrode holds higher electrocatalytic activity and better stability for methanol oxidation on the condition of mass ratio between CeO2 and Pt is equal to 7%.
The polyaniline/polysulfone (PAN/PSF) composite film modified electrodes doped with cerium oxide were prepared by electropolymerization, and then Pt particles were deposited into this composite film to obtain the Pt modified cerium oxide/polyaniline/polysulfone (Pt-CeO2/PAN/PSF) electrodes. Their morphology and chemical component were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS), respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were applied to investigate the electrocatalytic activity of the electrode for methanol oxidation. The results show that the composite film has a bi-layer structure with asymmetrical pores, and platinum and cerium oxide particles are uniformly dispersed in the modified film electrodes. The average size of particles is about 80 nm. The electrode holds higher electrocatalytic activity and better stability for methanol oxidation on the condition of mass ratio between CeO2 and Pt is equal to 7%.
2011, 28(3): 308-313
doi: 10.3724/SP.J.1095.2011.00387
Abstract:
Electrodeposited Pb-polyacrylonitrile (PAN) -tungsten carbide (WC) composite coatings on Ti anode were prepared by adding PAN, WC and PbO solid particles in potassium sodium tartrate system. The influences of process conditions such as current density and temperature on the depositing rate and oxygen evolution kinetic parameters of composite coated electrodes were studied. The anodic polarization curves in ZnSO4-H2SO4 system show that the optimal process conditions are:current density of 1.5 A/cm2, temperature of 35℃, 15 g/L of PAN in bath and 40 g/L of WC. Comparing oxygen evolution kinetic parameters of composite coated electrodes with anodic polarization curves of pure lead coated electrode, it can be concluded that the electrochemical properties of Pb-PAN-WC composite coating is better.
Electrodeposited Pb-polyacrylonitrile (PAN) -tungsten carbide (WC) composite coatings on Ti anode were prepared by adding PAN, WC and PbO solid particles in potassium sodium tartrate system. The influences of process conditions such as current density and temperature on the depositing rate and oxygen evolution kinetic parameters of composite coated electrodes were studied. The anodic polarization curves in ZnSO4-H2SO4 system show that the optimal process conditions are:current density of 1.5 A/cm2, temperature of 35℃, 15 g/L of PAN in bath and 40 g/L of WC. Comparing oxygen evolution kinetic parameters of composite coated electrodes with anodic polarization curves of pure lead coated electrode, it can be concluded that the electrochemical properties of Pb-PAN-WC composite coating is better.
2011, 28(3): 314-319
doi: 10.3724/SP.J.1095.2011.00270
Abstract:
2-Undecyl-N-carboxymethyl-N-hydroxyethyl imidazoline was investigated as a corrosion inhibitor for carbon steel in 2% mass fracton of citric acid solution by means of mass loss test, polarization and AC impedance. The mass loss test results showed that the inhibitor was an excellent inhibitor for carbon steel in acid media with an inhibition efficiency of 86.4% at the mass concentration of 0.4%. The polarization curves indicated that the inhibitor behaved as a mixed type inhibitor while the single capacitive loop in the Nyquist plots revealed that the corrosion was a charge transfer controlled process. The adsorption of the inhibitor was found to follow the Langmuir adsorption isotherm and the involved mechanism consisted of a mixed adsorption between chemisorption and physisorption.
2-Undecyl-N-carboxymethyl-N-hydroxyethyl imidazoline was investigated as a corrosion inhibitor for carbon steel in 2% mass fracton of citric acid solution by means of mass loss test, polarization and AC impedance. The mass loss test results showed that the inhibitor was an excellent inhibitor for carbon steel in acid media with an inhibition efficiency of 86.4% at the mass concentration of 0.4%. The polarization curves indicated that the inhibitor behaved as a mixed type inhibitor while the single capacitive loop in the Nyquist plots revealed that the corrosion was a charge transfer controlled process. The adsorption of the inhibitor was found to follow the Langmuir adsorption isotherm and the involved mechanism consisted of a mixed adsorption between chemisorption and physisorption.
2011, 28(3): 320-325
doi: 10.3724/SP.J.1095.2011.00227
Abstract:
Hydrothermally prepared zinc oxide nanorods were characterized by scanning electron microscopy and infrared spectroscopy. The zinc oxide nanorod modified graphite electrode was prepared by intercalation for dopamine determination. Voltammetric behavior and reaction mechanism of dopamine at the modified graphite electrode were investigated with cyclic voltammetry and differential pulse voltammetry. The results showed that there were good voltammetric responses for dopamine at the modified electrode under optimal conditions, with peak currents greatly enhanced and an negative shift of anodic peak potential by 68 mV. Kinetic properties of the electrochemical process were also obtained:the number of transfer electrons(n) is 2 and the electron transfer coefficient (α) is 0.48. The peak currents of differential pulse voltammetry of dopamine are linear in the ranges of 5.0×10-7~1.0×10-4 mol/L with a detection limit of 1.0×10-7 mol/L at the signal-to-noise of 3. Relative standard deviation(RSD) is 3.42% for eight parallel detections of 1.0×10-5 mol/L dopamine. The recoveries of this proposed method for determination of dopamine hydrochloride injection solutions are in the range of 94.83%~104.5%.
Hydrothermally prepared zinc oxide nanorods were characterized by scanning electron microscopy and infrared spectroscopy. The zinc oxide nanorod modified graphite electrode was prepared by intercalation for dopamine determination. Voltammetric behavior and reaction mechanism of dopamine at the modified graphite electrode were investigated with cyclic voltammetry and differential pulse voltammetry. The results showed that there were good voltammetric responses for dopamine at the modified electrode under optimal conditions, with peak currents greatly enhanced and an negative shift of anodic peak potential by 68 mV. Kinetic properties of the electrochemical process were also obtained:the number of transfer electrons(n) is 2 and the electron transfer coefficient (α) is 0.48. The peak currents of differential pulse voltammetry of dopamine are linear in the ranges of 5.0×10-7~1.0×10-4 mol/L with a detection limit of 1.0×10-7 mol/L at the signal-to-noise of 3. Relative standard deviation(RSD) is 3.42% for eight parallel detections of 1.0×10-5 mol/L dopamine. The recoveries of this proposed method for determination of dopamine hydrochloride injection solutions are in the range of 94.83%~104.5%.
2011, 28(3): 326-332
doi: 10.3724/SP.J.1095.2011.00304
Abstract:
Chitosan-g-N-carboxymethyl-bi(2-benzoimidazole)-1, 2-ethandiol(CTS-g-N-CBBIE) was synthesized through grafting on the side chain of chitosan with 2-bromoacetic acid, chitosan, bi(2-benzoimidazole)-1, 2-ethandiol, chloroauric acid and sodium citrate as raw materials. Compsosite of CTS-g-N-CBBIE-NGS was obtained by means of intermixing purified nanogold sol (NGS) and CTS-g-N-CBBIE. The composite was adopted to act as the carrier of immobilized laccase from Trametes versicolor mainly by means of physical entrapment. The laccase-entrapped CTS-g-N-CBBIE-NGS composite with superiority of high laccase-loading (31.10 mg/g) and specific activity of immobilized enzyme(1.43 U/mg) was used to modify the glassy carbon electrode(GCE). Results from experiments conducted on this laccase modified glassy carbon electrode showed mediatorless direct electron transfer occurred between active site of laccase and laccase modified electrode in deaerated phosphate-citrate buffer solution (pH=5.0) (formal potential of quasi-reversible redox peaks corresponding to the T1 site copper ion in the laccase:576 mV(vs. AgCl/Ag)). Rate constant of electron transfer:228.3 s-1 was derived from relationship of separation of redox peaks and logarithm of scan rates. Laccase-entrapped matrix modified GCE also displayed bioelectrocatalytic effect on oxygen reduction reaction to some extent under low oxygen concentration(peak potential of laccase modified GCE for oxygen reduction reaction in air-saturated buffer solution at ca. 320 mV (vs. AgCl/Ag)). Oxygen reduction reaction was depressed when oxygen concentration increased. This laccase modified electrode was sensitive to variation of pH and its inferiority originated from undesirable usability and long-term stability. It is essential for higher bioelectrocatalytic function on oxygen reduction reaction of laccse modified electrode that constituent of composite to immobilize enzyme which was used to modify electrode must be optimized.
Chitosan-g-N-carboxymethyl-bi(2-benzoimidazole)-1, 2-ethandiol(CTS-g-N-CBBIE) was synthesized through grafting on the side chain of chitosan with 2-bromoacetic acid, chitosan, bi(2-benzoimidazole)-1, 2-ethandiol, chloroauric acid and sodium citrate as raw materials. Compsosite of CTS-g-N-CBBIE-NGS was obtained by means of intermixing purified nanogold sol (NGS) and CTS-g-N-CBBIE. The composite was adopted to act as the carrier of immobilized laccase from Trametes versicolor mainly by means of physical entrapment. The laccase-entrapped CTS-g-N-CBBIE-NGS composite with superiority of high laccase-loading (31.10 mg/g) and specific activity of immobilized enzyme(1.43 U/mg) was used to modify the glassy carbon electrode(GCE). Results from experiments conducted on this laccase modified glassy carbon electrode showed mediatorless direct electron transfer occurred between active site of laccase and laccase modified electrode in deaerated phosphate-citrate buffer solution (pH=5.0) (formal potential of quasi-reversible redox peaks corresponding to the T1 site copper ion in the laccase:576 mV(vs. AgCl/Ag)). Rate constant of electron transfer:228.3 s-1 was derived from relationship of separation of redox peaks and logarithm of scan rates. Laccase-entrapped matrix modified GCE also displayed bioelectrocatalytic effect on oxygen reduction reaction to some extent under low oxygen concentration(peak potential of laccase modified GCE for oxygen reduction reaction in air-saturated buffer solution at ca. 320 mV (vs. AgCl/Ag)). Oxygen reduction reaction was depressed when oxygen concentration increased. This laccase modified electrode was sensitive to variation of pH and its inferiority originated from undesirable usability and long-term stability. It is essential for higher bioelectrocatalytic function on oxygen reduction reaction of laccse modified electrode that constituent of composite to immobilize enzyme which was used to modify electrode must be optimized.
2011, 28(3): 333-337
doi: 10.3724/SP.J.1095.2011.00291
Abstract:
A modified electrode was developed by immobilizing horseradish peroxidase (HRP) onto a biocompatible glassy carbon electrode (GCE) modified with a DNA/poly (ferrocenylsilane) (PFS)/room temperature ionic liquid(RTIL) film and the as-prepared GCE/DNA/PFS/RTIL/HRP electrode provides both a biocompatible microenvironment for HRP to keep its good bioactivity and an effective pathway of electron transfer between the redox center of HRP and the electrode surface. The modified electrode showed a good electrocatalytic behavior toward the reduction of H2O2. The electrocatalytic behaviors of GCE/DNA/PFS/RTIL/HRP to the reduction of H2O2 were investigated by cyclic voltammograms and amperometric technique in detail. Under the optimized conditions, the modified electrode shows fast response to the electrocatalytic oxidation of H2O2 and the steady current was observed within 2 s. The catalytic current is linear to the H2O2 concentration in the range of 3.25 μmol/L to 1.47 mmol/L and 1.86 mmol/L to 5.35 mmol/L. The detection limit was 0.86 μmol/L based on the criterion of a signal-to-noise ratio of 3. The biosensor showed high sensitivity, good reproducibility and stability. Furthermore, the modified electrode also showed a good electrocatalytic behavior toward the reduction of O2.
A modified electrode was developed by immobilizing horseradish peroxidase (HRP) onto a biocompatible glassy carbon electrode (GCE) modified with a DNA/poly (ferrocenylsilane) (PFS)/room temperature ionic liquid(RTIL) film and the as-prepared GCE/DNA/PFS/RTIL/HRP electrode provides both a biocompatible microenvironment for HRP to keep its good bioactivity and an effective pathway of electron transfer between the redox center of HRP and the electrode surface. The modified electrode showed a good electrocatalytic behavior toward the reduction of H2O2. The electrocatalytic behaviors of GCE/DNA/PFS/RTIL/HRP to the reduction of H2O2 were investigated by cyclic voltammograms and amperometric technique in detail. Under the optimized conditions, the modified electrode shows fast response to the electrocatalytic oxidation of H2O2 and the steady current was observed within 2 s. The catalytic current is linear to the H2O2 concentration in the range of 3.25 μmol/L to 1.47 mmol/L and 1.86 mmol/L to 5.35 mmol/L. The detection limit was 0.86 μmol/L based on the criterion of a signal-to-noise ratio of 3. The biosensor showed high sensitivity, good reproducibility and stability. Furthermore, the modified electrode also showed a good electrocatalytic behavior toward the reduction of O2.
2011, 28(3): 338-342
doi: 10.3724/SP.J.1095.2011.00295
Abstract:
The chloramphenicol(CAP) molecule-imprinted polymer(MIP) of o-aminophenol(OAP) on Pt (CAP-MIP-OAP/Pt) electrode was prepared via an electrochemical polymerization method using OAP as the functional monomer and CAP as the template molecule. This preparation method is simple. The as-prepared membrane is uniform and stable. The performances and configurations of the CAP-MIP-OAP/Pt and MIPOAP/Pt electrodes were investigated using scanning electron microscope (SEM) and electrochemical techniques. The results illustrated that the MIP-OAP/Pt electrode exhibited improved selectivity and sensitivity for the CAP detection. A linear region of the CAP detection is in the range of 4.33×10-8~3.09×10-6 mol/L. The detection limit is 2.5×10-8 mol/L. Therefore, the MIP-OAP/Pt electrode shows potential application for the enrichment and detection of CAP in the environmental water sample.
The chloramphenicol(CAP) molecule-imprinted polymer(MIP) of o-aminophenol(OAP) on Pt (CAP-MIP-OAP/Pt) electrode was prepared via an electrochemical polymerization method using OAP as the functional monomer and CAP as the template molecule. This preparation method is simple. The as-prepared membrane is uniform and stable. The performances and configurations of the CAP-MIP-OAP/Pt and MIPOAP/Pt electrodes were investigated using scanning electron microscope (SEM) and electrochemical techniques. The results illustrated that the MIP-OAP/Pt electrode exhibited improved selectivity and sensitivity for the CAP detection. A linear region of the CAP detection is in the range of 4.33×10-8~3.09×10-6 mol/L. The detection limit is 2.5×10-8 mol/L. Therefore, the MIP-OAP/Pt electrode shows potential application for the enrichment and detection of CAP in the environmental water sample.
2011, 28(3): 343-348
doi: 10.3724/SP.J.1095.2011.00207
Abstract:
The fluorescence spectroscopic technique has been used to demonstrate the formation of the inclusion complex of adriamycin (ADM) and β-cyclodextrin (β-CD). The effects of the reaction time, concentration and temperature on the inclusion reaction are investigated. The chemical stoichiometric ratio for the formation of the inclusion complexes is determined. The inclusion constant and thermodynamic parameters of the inclusion reactions at different temperatures are calculated. At 33℃ and pH=7.0, the inclusion constant, K is 2.98×106 L/mol. The K value diminishes with the increase of temperature. Thus, the inclusion reaction is an enthalpy driving and spontaneous exothermic reaction. After ADM and β-CD form the inclusion complex, the fluorescence intensity is increased because β-CD can increase the natural fluorescence of ADM. Therefore, the fluorescence spectroscopic technique is an excellent technique for the investigation of the inclusion reaction of ADM and β-CD. The linear regression equation of the quantitative determination of ADM by β-CD sensitized fluorescence method is F=5.64×108c+47.26, with a correlation coefficient of 0.9985. The detection limit is 6.30×10-8 mol/L.
The fluorescence spectroscopic technique has been used to demonstrate the formation of the inclusion complex of adriamycin (ADM) and β-cyclodextrin (β-CD). The effects of the reaction time, concentration and temperature on the inclusion reaction are investigated. The chemical stoichiometric ratio for the formation of the inclusion complexes is determined. The inclusion constant and thermodynamic parameters of the inclusion reactions at different temperatures are calculated. At 33℃ and pH=7.0, the inclusion constant, K is 2.98×106 L/mol. The K value diminishes with the increase of temperature. Thus, the inclusion reaction is an enthalpy driving and spontaneous exothermic reaction. After ADM and β-CD form the inclusion complex, the fluorescence intensity is increased because β-CD can increase the natural fluorescence of ADM. Therefore, the fluorescence spectroscopic technique is an excellent technique for the investigation of the inclusion reaction of ADM and β-CD. The linear regression equation of the quantitative determination of ADM by β-CD sensitized fluorescence method is F=5.64×108c+47.26, with a correlation coefficient of 0.9985. The detection limit is 6.30×10-8 mol/L.
2011, 28(3): 349-354
doi: 10.3724/SP.J.1095.2011.00210
Abstract:
A new approach to measure with hemoglobin (Hb)/nano-Au/chitosan (CS) -ZrO2/Au modified electrode was established. Zirconium dioxide(ZrO2) was dispersed in the chitosan(CS) to form a stable CSZrO2 composite. This composite was first coated on the surface of gold electrode to provide an amino group interface for assembling nano-Au, followed by the adsorption of Hb to form a bilayer of Hb/nano-Au. The Hb/nano-Au/CS-ZrO2/gold electrode was used as hydrogen peroxide (H2O2) sensor. Cycling voltammetric and chronoamperometric characterizations reveal that the modified electrode exhibit electrocatalytic behavior to H2O2. The results confirmed that the electrode exhibited high sensitivity, fast response, and linear response in the range of 3.9×10-6~1.8×10-3 mol/L(R=0.9956) with the lowest detection limit of 5.6×10-7 mol/L (S/N=3).
A new approach to measure with hemoglobin (Hb)/nano-Au/chitosan (CS) -ZrO2/Au modified electrode was established. Zirconium dioxide(ZrO2) was dispersed in the chitosan(CS) to form a stable CSZrO2 composite. This composite was first coated on the surface of gold electrode to provide an amino group interface for assembling nano-Au, followed by the adsorption of Hb to form a bilayer of Hb/nano-Au. The Hb/nano-Au/CS-ZrO2/gold electrode was used as hydrogen peroxide (H2O2) sensor. Cycling voltammetric and chronoamperometric characterizations reveal that the modified electrode exhibit electrocatalytic behavior to H2O2. The results confirmed that the electrode exhibited high sensitivity, fast response, and linear response in the range of 3.9×10-6~1.8×10-3 mol/L(R=0.9956) with the lowest detection limit of 5.6×10-7 mol/L (S/N=3).
2011, 28(3): 355-360
doi: 10.3724/SP.J.1095.2011.00328
Abstract:
In sodium hydroxide solution, oxacillin(OXA) can be bound to some basic triphenylmethane dyes such as methyl violet(MV), ethyl violet(EV) or malachite green(MG) to form a new product, resulting in a great enhancement of resonance Rayleigh scattering(RRS) and the appearance of a new RRS spectrum. The maximum RRS peak locates at 333 nm for MV system, 342 nm for EV system and 343 nm for MG system, respectively. The RRS intensity was directly proportional to the OXA concentration in the range of 0.080~0.60 mg/L for MV system, 0.040~0.40 mg/L for EV and MG systems, respectively. The lowest detection limits(3σ) of OXA were 0.064 mg/L for MV system, 0.024 mg/L for EV system, and 0.013 mg/L for MG system, respectively. Among these three systems, the MG system has the highest sensitivity, and the effects of the coexisting substances were investigated for this system. The results indicate that this assay has a good selectivity. The system is applied to the determination of oxacillin in human urine liquid, serum and commercial pharmaceuticals with satisfactory results.
In sodium hydroxide solution, oxacillin(OXA) can be bound to some basic triphenylmethane dyes such as methyl violet(MV), ethyl violet(EV) or malachite green(MG) to form a new product, resulting in a great enhancement of resonance Rayleigh scattering(RRS) and the appearance of a new RRS spectrum. The maximum RRS peak locates at 333 nm for MV system, 342 nm for EV system and 343 nm for MG system, respectively. The RRS intensity was directly proportional to the OXA concentration in the range of 0.080~0.60 mg/L for MV system, 0.040~0.40 mg/L for EV and MG systems, respectively. The lowest detection limits(3σ) of OXA were 0.064 mg/L for MV system, 0.024 mg/L for EV system, and 0.013 mg/L for MG system, respectively. Among these three systems, the MG system has the highest sensitivity, and the effects of the coexisting substances were investigated for this system. The results indicate that this assay has a good selectivity. The system is applied to the determination of oxacillin in human urine liquid, serum and commercial pharmaceuticals with satisfactory results.
2011, 28(3): 361-363
doi: 10.3724/SP.J.1095.2011.00355
Abstract:
Lactide was synthesized under high vacuum using ZnO as catalyst with the addition of stannous octanoate(Sn(Oct) 2) at different intervals. The highest temperature of lactide distillation was decreased to 197℃. Lactide crystal was characterized by means of IR spectrum and its melting point was measured. The surface tensions of L-lactic acids after dehydration, after dehydration followed with the addition of zinc oxide or addition of both zinc oxide and stannous octanoate were 38.8, 47.0 and 40.3 N/m, respectively. Their viscosities were 43.1049, 59.6774 and 48.9376 mPa·s, respectively. These experimental results showed stannous octanoate can help the cracking of the bond between acyl and oxide in the intermediate and the decrease of surface tension of reaction system.
Lactide was synthesized under high vacuum using ZnO as catalyst with the addition of stannous octanoate(Sn(Oct) 2) at different intervals. The highest temperature of lactide distillation was decreased to 197℃. Lactide crystal was characterized by means of IR spectrum and its melting point was measured. The surface tensions of L-lactic acids after dehydration, after dehydration followed with the addition of zinc oxide or addition of both zinc oxide and stannous octanoate were 38.8, 47.0 and 40.3 N/m, respectively. Their viscosities were 43.1049, 59.6774 and 48.9376 mPa·s, respectively. These experimental results showed stannous octanoate can help the cracking of the bond between acyl and oxide in the intermediate and the decrease of surface tension of reaction system.
2011, 28(3): 364-366
doi: 10.3724/SP.J.1095.2011.00351
Abstract:
The contents of polynuclear aromatic hydrocarbons (PAHs) in tar and smog of burned coal produced in 7 different areas have been measured using three-dimensional fluorescent method. The range of PAHs in coal tar is from 0.201~0.419 mg/g and in coal smog is from 1.1~3.2 μg/g. Scavenging capacity for PAHs in coal smog by β-CD solution was determined to be 65.6%. The results showed that:PAHs contents of coal smog is different as the origin of coal varies. The PAHs content in coal tar is in the order of 10-5 mol/L, and more than that in the order of (10-7 mol/L) in coal smog. As the producing area varies, the scavenging rates of PAHs in coal smog by β-CD solution is also different, the average scavenging rate of 7 kinds of selected coals was 38.4%. Hence, it is hopeful that the β-CD solution can be used as an effective removal agent for PAHs in coal smog.
The contents of polynuclear aromatic hydrocarbons (PAHs) in tar and smog of burned coal produced in 7 different areas have been measured using three-dimensional fluorescent method. The range of PAHs in coal tar is from 0.201~0.419 mg/g and in coal smog is from 1.1~3.2 μg/g. Scavenging capacity for PAHs in coal smog by β-CD solution was determined to be 65.6%. The results showed that:PAHs contents of coal smog is different as the origin of coal varies. The PAHs content in coal tar is in the order of 10-5 mol/L, and more than that in the order of (10-7 mol/L) in coal smog. As the producing area varies, the scavenging rates of PAHs in coal smog by β-CD solution is also different, the average scavenging rate of 7 kinds of selected coals was 38.4%. Hence, it is hopeful that the β-CD solution can be used as an effective removal agent for PAHs in coal smog.
