I describe the mechanism whereby ascorbic acid can hamper test systems involving a peroxide-generating system, peroxidase, and a benzidine-type indicator. In test media such as urines, abnormally high concentrations of ascorbic acid may give rise to false negatives in the determination of analytes such as glucose. Absorbance measurements in solution or reflectance measurements on commercially a...

It is well known that the determination of ascorbic acid in urine by titration with 2,6dichlorophenol indophenol in acid solution is not a specific method. Various interfering substances have been reported, such as sulfhydryl compounds (l), thiosulfate (2), and pyridium (medication) (3). The same limitations apply to other oxidation-reduction methods, except when the reducing substance is deter...

It is well known that the determination of ascorbic acid in urine by titration with 2,6dichlorophenol indophenol in acid solution is not a specific method. Various interfering substances have been reported, such as sulfhydryl compounds (l), thiosulfate (2), and pyridium (medication) (3). The same limitations apply to other oxidation-reduction methods, except when the reducing substance is deter...

A new and simple flow injection method followed by atomic absorption spectrometry has been developed for the indirect determination of ascorbic acid. The proposed method is based on oxidation of ascorbic acid to dehydroascorbic acid using a solid-phase manganese dioxide (30% m/m suspended on silica gel beads) reactor. The flow of the sample through the column reduces the MnO2 to Mn(II) in an ac...

In this work, we investigated the immobilization of methylene blue in a methyltrimethoxysilane sol-gel ceramic film on a glassy carbon electrode. Up to a certain saturation level, under our conditions, it was found that the methylene blue was tightly held and did not leach out into aqueous solutions, even with continuous immersion for up to 1 month. The electrochemical behavior of the immobiliz...

This paper describes an investigation of the conditions affecting the determination of phosphate using the reduced phosphoantimonylmolybdic acid method. The aim was to develop a determination method with faster kinetics than the original procedure of Murphy and Riley, for automation using flow-injection analysis. Optimum colour formation was found to occur at [H+ ] / [MOO:-] ratios between SW30...

Compoundswhich interfere in the analytic determination of uric acid are referred to as “non-urate chromogens.”Ascorbic acid, when added to serum, causes a significant increase in apparent uric acid levels as determined by a carbonate-phosphotungstate method. The ratio of apparent urate to ascorbicacid is 1:3, a value in close agreement with that obtained for the ratio of labile non-urate chromo...

The electrochemical behavior of ascorbic acid and rutin using a poly(L-arginine)-graphene oxide modified glassy carbon electrode (PLA-GO/GCE) has been studied by cyclic voltammetry and chronoamperometry. The modified electrode succeeds in distinguishing the electrochemical responses of ascorbic acid and rutin in a mixture solution due to its high electron transfer rate and good catalytic abilit...