The H-point standard addition method was applied to kinetic data for simultaneous determination of citric and ascorbic acid or selective determination of ascorbic acid in presence of citric acid. The method is based on the difference in the rate of reaction of citric and ascorbic acid with copper(II)-ammonia complex. The linear dynamic ranges for the two analytes of citric and ascorbic acid are...

BACKGROUND Ascorbic acid is one of the most important vitamins to monitor in dietary sources (juices and vitamins) and biological liquids. RESULTS Silica and silica-titania xerogels doped with Mo,P-heteropoly compounds (HPC) have been synthesized varying titanium(IV) and HPC content in sol. Their surface area and porosity have been studied with nitrogen adsorption and scanning electron micros...

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 ...

abstract: Ascorbic acid (Vitamin C) is an essential Vitamin which participates in many different biological processes. The ascorbic acid content in vegetables and fruits is a maturity index and its determination in such samples is of special interest in quality control. In this paper we present a titrimetric method with potassium bromide for the determination of ascorbic acid in walnut, cabbage...

A flow injection method is reported for the determination of ascorbic acid based on amperometric detection, using a cobalt(II) phthalocyanine (CoPc) modified graphite-epoxy electrode. The amperometric respons was evaluated with regard to pH, ionic strength of the electrolyte, flow rate of the carrier solution, injected sample volume and conditioning time of the electrode. The limit of detec...

1. The kinetics of the reaction between HCHO and I-ascorbic acid or chemically related substances have been studied. 2. Indirect evidence is produced for the possible structure of the HCHO-1-ascorbic acid complex. / 3. Lugg's method for determination of I-ascorbic acid has been examined from the point of view of the above experiments, and necessary precautions are stressed. 4. Suggestions for o...

A novel optical method for the determination of thiram has been developed using surface plasmon resonance peak of gold nanoparticles (AuNPs). The stable and dispersed AuNPs were directly synthesized by reduction of HAuCl4 with ascorbic acid in micellar media according to a simple approach. The presence of thiram during formation of AuNPs results in the decrease of the intensity of plasmon reson...

A simple approach based on cyclic voltammetry (CV) was developed for the simultaneous determination of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA) using a modified glassy carbon paste electrode (GCPE). In the present study, analytical parameters were optimized and electrochemical performance of modified electrode was investigated. The calibration curves were obtained ...

Voltammetric techniques have been considered as important methods among the analytical techniques used for the identification and determination of trace concentrations of many biological molecules such as L-ascorbic acid (AA). L-ascorbic acid is an electro-active molecule, though it is difficult to determine its value directly with a majority of electrodes made of carbon and transition metals, ...