Micro and semimicro determination of thiols with ion-selective electrodes

Abstract

This paper describes the potentiometric determination of a variety of thiols. Microamounts (0.01 to 0.1 mM) are titrated with 0.01N mercuric perchlorate while semimicroamounts (0.1 to 0.5 mM) are titrated with 0.05N mercuric perchlorate. A bromide selective indicator electrode and a single-junction reference electrode are used with an expanded-scale pH meter to monitor the emf. Other indicator electrodes based on a silver sulfide matrix may also be used. The preferred solvent is acetone while ethanol andp-dioxane have limited applicability. The electrode response is slower in general than for other titrations using ion-selective electrodes, particularly for the more complex thiols and those attached to a heterocyclic ring system.