The effect of pH on the biosensor platform was investigated between 1 and 13 (Figure4) since real samples could have components changing acidity. There was a slight response between the values of pH 2 to pH 8. Due to a small activity loss or the degradation of the enzyme, at pH 9, slightly less yellow colour formation was obtained. At alkaline values more than 10, the yellow colour formation was instant after pouring the ATChI on to the enzyme-chromophore stabilized part, and the density of the yellow increased immensely. This can be explained by cleavage of either DTNB or the ATChI. Therefore, the sensor would require well buffered treatments especially for strongly alkaline samples.