Photochemical reactions of 4-nitroquinoline 1-oxide(4NQO) with methionine-containing dipeptides Met-Met, Ala-Met, Met-Lue and Met-Gly have been studies by using 248 nm laser flash photolysis. The formation of α-alkyl...Photochemical reactions of 4-nitroquinoline 1-oxide(4NQO) with methionine-containing dipeptides Met-Met, Ala-Met, Met-Lue and Met-Gly have been studies by using 248 nm laser flash photolysis. The formation of α-alkyl radicals was observed, and their rate constants of formation were obtained. The reaction mechanism that the α-alkyl radicals produced via an electron transfer process between triplet 4NQO and methionine-containing dipeptide was proposed.展开更多
In this study,simple and sensitive spectrophotometric method for the determination of folic acid(VB9)in pharmaceutical formulations was reported.The proposed method was based on the reaction between folic acid and 1,2...In this study,simple and sensitive spectrophotometric method for the determination of folic acid(VB9)in pharmaceutical formulations was reported.The proposed method was based on the reaction between folic acid and 1,2-naphthoquine-4-sulphonate(NQS)at alkaline medium(pH 11)to form deep yellow product.Beer’s law was obeyed in the range of 0.75-10.5μg/mL of folic acid at maximum wavelength of 436 nm.Under optimized reaction conditions,linear regression equation of the calibration curve was y=0.048 x+0.038(μg/mL)with a linear correlation coefficient of 0.9988.The limit of detection(LOD)and limit of quantification(LOQ)were found to be 0.159μg/mL and 0.531μg/mL,respectively.The method was successfully applied to the determination of folic acid in pharmaceutical formulations.展开更多
文摘Photochemical reactions of 4-nitroquinoline 1-oxide(4NQO) with methionine-containing dipeptides Met-Met, Ala-Met, Met-Lue and Met-Gly have been studies by using 248 nm laser flash photolysis. The formation of α-alkyl radicals was observed, and their rate constants of formation were obtained. The reaction mechanism that the α-alkyl radicals produced via an electron transfer process between triplet 4NQO and methionine-containing dipeptide was proposed.
文摘In this study,simple and sensitive spectrophotometric method for the determination of folic acid(VB9)in pharmaceutical formulations was reported.The proposed method was based on the reaction between folic acid and 1,2-naphthoquine-4-sulphonate(NQS)at alkaline medium(pH 11)to form deep yellow product.Beer’s law was obeyed in the range of 0.75-10.5μg/mL of folic acid at maximum wavelength of 436 nm.Under optimized reaction conditions,linear regression equation of the calibration curve was y=0.048 x+0.038(μg/mL)with a linear correlation coefficient of 0.9988.The limit of detection(LOD)and limit of quantification(LOQ)were found to be 0.159μg/mL and 0.531μg/mL,respectively.The method was successfully applied to the determination of folic acid in pharmaceutical formulations.
