Flow Injection Amperometric Determination of Ascorbic Acid Using a Photoelectrochemical Reaction after Immobilization of Methylene Blue on Muscovite

Authors : Yusuf DİLGİN, Zekerya DURSUN, Gürel NİŞLİ

Pages : 167-180

View : 14 | Download : 8

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The photoelectrochemical determination of ascorbic acid insert ignore into journalissuearticles values(AA); was studied based on the photochemical reduction of methylene blue insert ignore into journalissuearticles values(MB); in 0.1 M phosphate buffer insert ignore into journalissuearticles values(pH 7.0);. MB was used as a redox mediator for the modification of a carbon paste electrode insert ignore into journalissuearticles values(CPE); due to its facile reducible-oxidizible behaviour. Muscovite, which has a layered structure, was found to be a good and stable supporting material for the immobilization of MB by an ion exchange reaction. The dye is strongly retained and not easily leached from the matrix. MB was reduced to nearly quasi-reversible at the modified carbon paste electrode insert ignore into journalissuearticles values(MCPE);. The oxidation peak potential of leuco-methylene blue insert ignore into journalissuearticles values(LMB); shifted from --100 mV to 50 mV in the presence of AA. For photoelectrochemical amperometric studies, the operational potential was kept constant at + 50 mV according to the oxidation of LMB, which was produced from the chemical reaction between AA and MB on the modified electrode surface. A laboratory-built flow cell system was constructed for the direct irradiation of the electrode surface with a 500-W halogen lamp. The optimum conditions for the flow injection insert ignore into journalissuearticles values(FI); amperometric determination of AA were 1.5 mL/min flow rate, 50 m L sample loop and 50 cm transmission tubing length and at a frequency of 60 samples per hour. AA could be determined in the concentration range 1.0 x 10-6 - 1.0 x 10-4 M by using a photoelectrochemical FI method. The detection limit of this method was 1.0 x 10-8 M. The relative standard deviation of five replicate injections of 6.0 x 10-5 M AA was 2.0% in photoelectrochemical FI. The results obtained by the proposed procedure are in good agreement with those established using the triiodide procedure for the AA determination of pharmaceutical products.
Keywords : Photoelectrochemical analysis, flow injection analysis, ascorbic acid, muscovite, methylene blue