NOVEL-APPROACH TO THE DEVELOPMENT OF ALKALINITY AND ACIDITY DETECTORS

A novel approach to the development of acidity and alkalinity field te sts, based on length of stain detectors, is discussed. The detectors c onsist of glass capillaries filled with sol-gel silica powder doped wi th pH indicators. When water is sampled through the tube detectors the alkaline or acidic species titrate the silanol groups on the glass su rface, in the presence of the immobilized indicator, and colour a sect ion of the capillary. The length of the coloured section depends on th e alkalinity (or acidity) of the sampled solution. The effects of glas s parameters, such as concentration of the silanol groups and the type and concentration of the immobilized pH indicators, are discussed.