ION-SELECTIVE ELECTRODES FOR THE DETERMINATION OF SALICYLIC-ACID - THEIR OPERATIONAL FEATURES AND APPLICATION TO ANALYSIS

It is shown that the super-Nernstian slope of the electrode function a nd minima in the potential-pH curves observed for salicylate-selective electrodes based on liquid ion exchangers can be explained to a first approximation by taking into account the extraction of salicylic acid in the molecular form into the membrane, in which it acts as a solvat ing additive with respect to ion associates and free salicylate ions. The selectivity of such electrodes for salicylate ions essentially dep ends on pH. A procedure is proposed for the rapid evaluation of the co ncentration of salicylic acid impurities in sulfosalicylic acid.