WHY CANT I USE A MATHEMATICAL CORRECTION TECHNIQUE (compensating matrix of interferences) TO CORRECT FOR A SENSORS RESPONSE TO INTERFERING GASES?
Electrochemical sensors do not lend themselves to the use of mathematical correction, a matrix, to correct for cross interfering gases. Although in principle it is possible to carry out a mathematical correction, it is only practical if the sensor’s response to interfering gases is small (typically less than 5%). There are, however, two major technical difficulties in trying to rely on this method to remove the effects of cross sensitivities: • The sensor’s characteristics change continuously with time. This adds a substantial degree of uncertainty. When the interference response of the sensor is large or uncertain, it is impossible to achieve acceptable accuracy by mathematical correction techniques. A better design consists of using a chemical filter or a scavenging electrode to minimize interference. Only when one is assured of the effectiveness of these primary cross interfering barriers, can a limited back-up mathematical correction be used to remove any residual interference. But
