An electrode of the second kind for aspirin determination in tablet formulations

This paper describes the construction of an electrode of the second kind, P t\Hg\Hg-2(Salic)(2)\Graphite, sensitive to salicylate. This electrode respo nds to the salicylate ion with a sensivity of 58.66 mV/decade over the rang e 6.0x10(-4) - 1.0x10(-1) mol/l at pH 6.0 and an ionic strength of 0.500 - 3.00 mol/l, adjusted with NaClO4. The electrode is easily constructed, show s a fast response time, is low in cost, has excellent response stability, a nd has a lifetime greater than 18 months, which is much longer than those r eported earlier for other systems. The influence of 10 different carboxylat e and inorganic anions on the electrode response showed that there was negl igible interference by most of these ions. It was used to determine aspirin in tablets (after hydrolysis of acetylsalicylic acid to salicylate) by mea ns of the standard additions method. The results obtained using this electr ode for aspirin determination, in three different samples of antithermic dr ugs, compared favorably with the results given by the British Pharmacopoeia method.