RESUMO
Screen-printed carbon electrodes (SPCEs) electrochemically platinised (Pt-SPCEs) and screen-printed platinised carbon electrodes (SPC(Pt)Es) have been chronoamperometrically characterized for the determination of formaldehyde (FA). The oxidation current registered at 600 mV in the FA concentration range from 0.99 to 9.09 mmol L(-1), led to higher precision values in terms of repeatability and reproducibility when using SPC(Pt)Es. SPC(Pt)Es have been also used for alcohol oxidase (AOX) cross-linked immobilization in the development of enzymatic biosensors for FA. The enzymatic reaction produces hydrogen peroxide, which has been chronoamperometrically monitored and related to FA concentration in different kinds of samples. Experimental design methodology has been performed to optimize the pH and the applied potential. This method has shown a repeatability and reproducibility of 3% (n=4) and 6% (n=4) respectively, related to the slopes of the calibration curves performed in the range from 60 to 460 µmol L(-1). The use of this kind of biosensor, which has a detection capability of 60 µmol L(-1) for a given probability of false positive and negative equal to 0.05, has been probed in the determination of FA in commercial samples for histology.
