Abstract: The present invention relates to a sensor arrangement adapted to evaluate an instant quality related value of a measured liquid sample (“S”) by applying a discontinuous and/or a continuous signal (“V”) to a number of electrodes (2, 3, 4), which are in electrical contact with said liquid sample (“S”), where a current (11, 12, 13), or equivalent quantity, measured at different potentials (voltage levels) between a reference electrode (3) and at least one working electrode (2 or 4), is evaluated at least at such time sequences where said measured current reflects the presence of any redox-active component, that may either be oxidation, reduction or neutral, at said working electrode (2 or 4).