In this study, incorporation of iron ion-doped natrolite nanozeolite, multi-wall carbon nanotubes into chitosan-coated glassy carbon electrode for the simultaneous determination of ascorbic acid, epinephrine, uric acid and tyrosine is studied. The results show that the combination of multi-wall carbon nanotubes and iron ion-doped natrolite zeolite causes a dramatic enhancement in the sensitivit...

A new method for the determination of ascorbic, dehydroascorbic and 2.3-diketogulonic acids in animal tissues, blood and urine is described. The material for analysis is homogenized in the presence of stannous chloride in trichloracetic acid and the extract is divided into three aliquots: in one part the ascorbic acid is converted into dehydroascorbic acid by oxidation with bromine water, in th...

9/6 10 11 12 13 14 15 16 17 18 van Euler and Klussman (4), van Eekelen et al. (5), and Harris et al. (6). Harris et al. (6), van Eekelen et al. (7), and Johnson and Zilva (8) have shown that following the intake of large amounts of ascorbic acid the urinary excretion of reducing substances increases. Application of the reduction reaction to the quantitative determination of ascorbic acid requir...

Numerous methods have been reported for the determination of vitamin C but most of the methods are tedious., lengthy, time consuming and not free from interference. In the present spectro-photoraetric method, selenium dioxide reacts with ascorbic acid, produces a fine orange colored suspension. This reaction was utilized for the determination of ascorbic acid in blood and urine. The color was r...

A new and simple method followed by atomic absorption spectrometry has been developedfor indirect determination of ascorbic acid (AA). The proposed method was based on the oxidationof AA to dehydroascorbic acid with Cu2+cation(200mgL-1)in an ammonium thiocyanatesolution atpH2.4. AA reduces Cu2+to Cu+followed by the precipitation of Cu+ with SCN-. Then, the excess ofCu2+in the solution was measu...

A novel biosensor for l-ascorbic acid determination in different beverages was elaborated. The ascorbate oxidase enzyme (AAO) from Cucurbita sp., EC 1.10.3.3, was immobilized on a screen-printed carbon electrode with poly(ethylene glycol) (400) diglycidyl ether (PEGDGE) as a crosslinking agent. The standards and samples were measured first with a blank electrode. An inert protein, bovine serum ...