A simple and sensitive spectroelectrochemistry method for the determination of vitamin K3 was developed by combining electrolysis and fluoremetry. This method was based on that vitamin K3 was reduced at a glassy carbo...A simple and sensitive spectroelectrochemistry method for the determination of vitamin K3 was developed by combining electrolysis and fluoremetry. This method was based on that vitamin K3 was reduced at a glassy carbon electrode, and its product with characteristic fluorescence at 420 nm was determined with excitation wavelength at 309 nm. Under optimized electrochemical reaction conditions and fluorescent experiment parameters, the fluorescence intensity was proportional to the concentration of vitamin K3 in a range from 3.50×10^-7 to 1.05×10^-5 mol/L with a correlation coefficient of 0.9991, and detection limit was estimated to be 7.50× 10^-8 mol/L at a signal/noise ra- tio of 3. The relative standard deviation was less than 4.3%（n=5） and the recovery was in a range of 97%-105% for the determination of vitamin K3 in pharmaceutical preparations. The result is satisfactory for the determination of vitamin K3 as comparison to that from HPLC method.展开更多
Radiation-induced grafting of styrene onto polytetrafluoroethylene (PTFE) membranes was studied by a simultaneous irradiation technique.Grafting was carded out usingγ-radiation from a ^(60)Co source at room temperatu...Radiation-induced grafting of styrene onto polytetrafluoroethylene (PTFE) membranes was studied by a simultaneous irradiation technique.Grafting was carded out usingγ-radiation from a ^(60)Co source at room temperature. Effects of absorbed dose,atmosphere,dose rate,and the concentration of initial monomer on the degree of grafting (DOG) were investigated and the most appropriate grafting condition was obtained.Subsequently,sulphonation of the grafted PTFE membrane (PTFE-g-PS) was carried out and a series of ion exchange membranes (PTFE-g-PSSA) was prepared.Further characterizations of FTIR,TGA,and SEM testified that grafting and sulphonation of the membranes were successfully processed;moreover,grafting of styrene not only occurred in the surface of PTFE membrane,but also in the micropores of the membrane.Ion exchange capacity (IEC) and conductivity were found increase with the grafting yield.The results suggest that at a low dose,such as 17 kGy,the ion exchange membrane (IEM) which will be suitable for vanadium redox battery (VRB) use can be obtained.展开更多
Visible spectroscopic and electrochemical methods were used to study the interactions between DNA and fuchsin basic（FB）. FB has an irreversible electro-oxidation peak in 5 mmol/L Tris-HCl buffer solution at pH = 7.4...Visible spectroscopic and electrochemical methods were used to study the interactions between DNA and fuchsin basic（FB）. FB has an irreversible electro-oxidation peak in 5 mmol/L Tris-HCl buffer solution at pH = 7.4 on a glassy carbon electrode（GCE）. After adding certain concentration of dsDNA, the oxidation peak current of FB decreases, but the peak potential hardly changes. The visible absorption spectroscopic study shows that the binding mode of FB to dsDNA is intercalative binding and electrostatic binding when the ratio of the concentration of dsDNA to FB is smaller than 0. 2, and anew substance, which produces a new absorption peak, is obtained via a covalent binding between dsDNA and FB apart from intercalative binding and electrostatic binding when the ratio of the concentration of dsDNA to FB is larger than 0. 2. The visible absorption spectra varies no longer when the ratio of the concentration of dsDNA＇to FB is larger than 1.5. A mean binding ratio of dsDNA to FB was determined to be 1.4： 1, suggesting that two complexes FB-dsDNA and FB-2dsDNA be formed. The interaction between FB and ssDNA was only electrostatic binding. The more powerful interaction of FB with dsDNA than with ssDNA may be applied for the recognition of dsDNA and ssDNA, and in DNA biosensor as hybridization indicator.展开更多
基金Supported by the National Nature Science Foundation of China(No.20635020)the Open-end Fund of State Key Labo-ratory of Fine Chemicals, China(No.KF0508)
文摘A simple and sensitive spectroelectrochemistry method for the determination of vitamin K3 was developed by combining electrolysis and fluoremetry. This method was based on that vitamin K3 was reduced at a glassy carbon electrode, and its product with characteristic fluorescence at 420 nm was determined with excitation wavelength at 309 nm. Under optimized electrochemical reaction conditions and fluorescent experiment parameters, the fluorescence intensity was proportional to the concentration of vitamin K3 in a range from 3.50×10^-7 to 1.05×10^-5 mol/L with a correlation coefficient of 0.9991, and detection limit was estimated to be 7.50× 10^-8 mol/L at a signal/noise ra- tio of 3. The relative standard deviation was less than 4.3%（n=5） and the recovery was in a range of 97%-105% for the determination of vitamin K3 in pharmaceutical preparations. The result is satisfactory for the determination of vitamin K3 as comparison to that from HPLC method.
基金Supported by The Scientific Research Foundation of State's Education Ministry for the Returned Overseas Chinese Scholars.
文摘Radiation-induced grafting of styrene onto polytetrafluoroethylene (PTFE) membranes was studied by a simultaneous irradiation technique.Grafting was carded out usingγ-radiation from a ^(60)Co source at room temperature. Effects of absorbed dose,atmosphere,dose rate,and the concentration of initial monomer on the degree of grafting (DOG) were investigated and the most appropriate grafting condition was obtained.Subsequently,sulphonation of the grafted PTFE membrane (PTFE-g-PS) was carried out and a series of ion exchange membranes (PTFE-g-PSSA) was prepared.Further characterizations of FTIR,TGA,and SEM testified that grafting and sulphonation of the membranes were successfully processed;moreover,grafting of styrene not only occurred in the surface of PTFE membrane,but also in the micropores of the membrane.Ion exchange capacity (IEC) and conductivity were found increase with the grafting yield.The results suggest that at a low dose,such as 17 kGy,the ion exchange membrane (IEM) which will be suitable for vanadium redox battery (VRB) use can be obtained.
文摘Visible spectroscopic and electrochemical methods were used to study the interactions between DNA and fuchsin basic（FB）. FB has an irreversible electro-oxidation peak in 5 mmol/L Tris-HCl buffer solution at pH = 7.4 on a glassy carbon electrode（GCE）. After adding certain concentration of dsDNA, the oxidation peak current of FB decreases, but the peak potential hardly changes. The visible absorption spectroscopic study shows that the binding mode of FB to dsDNA is intercalative binding and electrostatic binding when the ratio of the concentration of dsDNA to FB is smaller than 0. 2, and anew substance, which produces a new absorption peak, is obtained via a covalent binding between dsDNA and FB apart from intercalative binding and electrostatic binding when the ratio of the concentration of dsDNA to FB is larger than 0. 2. The visible absorption spectra varies no longer when the ratio of the concentration of dsDNA＇to FB is larger than 1.5. A mean binding ratio of dsDNA to FB was determined to be 1.4： 1, suggesting that two complexes FB-dsDNA and FB-2dsDNA be formed. The interaction between FB and ssDNA was only electrostatic binding. The more powerful interaction of FB with dsDNA than with ssDNA may be applied for the recognition of dsDNA and ssDNA, and in DNA biosensor as hybridization indicator.
