RESUMO
Different very simple single-use alcohol enzyme sensors were developed using alcohol oxidase (AOX) from three different yeast, Hansenula sp., Pichia pastoris and Candida boidinii, and employing three different commercial mediator-based Screen-Printed Carbon Electrodes as transducers. The mediators tested, Prussian Blue, Ferrocyanide and Co-phthalocyanine were included into the ink of the working electrode. The procedure to obtain these sensors consists of the immobilization of the enzyme on the electrode surface by adsorption. For the immobilization, an AOX solution is deposited on the working electrode and left until dried (1h) at room temperature. The best results were obtained with the biosensor using Screen-Printed Co-phthalocyanine/Carbon Electrode and AOX from Hansenula sp. The reduced cobalt-phthalocyanine form is amperometrically detected at +0.4V (vs. Ag pseudo reference electrode). This sensor shows good sensitivity (1211 nA mM(-1)), high precision (2.1% RSD value for the slope value of the calibration plot) and wide linear response (0.05-1.00 mM) for ethanol determination. The sensor provides also accurate results for ethanol quantification in alcoholic drinks.
Assuntos
Bebidas Alcoólicas/análise , Técnicas Biossensoriais/métodos , Candida/enzimologia , Carbono/química , Etanol/análise , Pichia/enzimologia , Oxirredutases do Álcool , Eletrodos , Enzimas Imobilizadas/metabolismo , Etanol/metabolismo , Ferrocianetos/química , Indóis/química , Compostos Organometálicos/química , Oxirredução , Sensibilidade e EspecificidadeRESUMO
The first fructose sensor using a commercial screen-printed ferrocyanide/carbon electrodes (SPFCE) is reported here. The ferrocyanide is included in the carbon ink of the commercial screen-printed carbon electrode. The immobilization of enzyme d-fructose dehydrogenase (FDH) was carried out in an easy way. An aliquot of 10µL FDH was deposited on the electrode surface and left there until dried (approximately 1h) at room temperature. The sensor, so constructed, shows a good sensitivity to fructose (1.25µA/mM) with a slope deviation of ±0.02µA/mM and a linear range comprised between 0.1 and 1mM of fructose, with a limit of detection of 0.05mM. These sensors show good intersensors reproducibility after a previous pretreatment and a high stability. Fructose was determined in real samples as honey, Cola, fruit juices (orange, tomato, apple and pineapple), red wine, red and white grapes, musts and liquor of peach with a good accuracy.
