A Comparison Between Pulsed Sonovoltammetry and Low Power Laser Activated Voltammetry for the Electroanalysis of Ascorbic Acid in a Commercial Fruit Drink

Abstract

A comparison is made between two 'dual activation' electroanalytical techniques for the detection and measurement of vitamin C (L-ascorbic acid) in a commercially available fruit drink via its two electron oxidation at platinum electrodes. Glucose is found not to interfere with the analytical response. First in sonovoltammetry pulses of 25 Wcm ¹2 are applied and the current response characterized in the 'pulse off' period where a current plateau is attained. Second in laser activated voltammetry a 10 Hz pulsed laser (532 nm, ca. 240 Wcm ¹2 average intensity) is used to 'burn' surface adsorbed passivating species off the electrode. Both methods cause agitation of the solution in the bulk phase or at the electrode-solution interface and lead to regular renewal of the diffusion layer. The mass transport limited oxidation currents so obtained are found to scale with ascorbic acid concentration in media where electroanalysis without simultaneous ultrasonic or laser stimulation may be precluded due to electrode passivation. Application to the quantitative electroanalysis of ascorbic acid in the fruit drinks Ribena and 'No added sugar' Ribena is reported. The results obtained are in excellent agreement with those yielded by independent chemical and electrochemical methods.

Electrochemical Detection of Nitrate at a Copper Modified Electrode Under the Influence of Ultrasound

“…Electrochemical measurements were conducted using a mAutolab computer controlled potentiostat (Eco-Chemie, Utrecht, The Netherlands) with a standard three electrode con®guration. The dimensions and electrode arrangement within the cell have been previously described [3]. Copper wire (2 mm diameter) mounted ush in a PTFE coating or wound into a short coil (0.25 mm diameter, 3 cm length) served as the working electrode with spiral wound platinum wire as the counter electrode and a saturated calomel (Radiometer, Copenhagen) reference electrode.…”

An Introduction to Sonoelectrochemistry

“…Limiting currents increase due to increased mass transport and electrode surface passivation is prevented Vitamin C analysis [54] Determination of manganese [55] Electrodeposition and electroless…”

Aplicação do ultra-som em sistemas eletroquímicos: considerações teóricas e experimentais

“…Um outro trabalho de Akkermans et al 97 mostrou a comparação de técnicas eletroanalí-ticas (sonovoltametria pulsada e voltametria de remoção por laser) para a detecção da vitamina C em sucos de frutas. Compton e Matysik 98 analisaram o comportamento sonovoltamétrico do ácido ascórbico e do ácido deidroascórbico sobre eletrodos de carbono vítreo usando a sonovoltametria pulsada.…”