A durable solid contact sulfide sensor based on a ceric acrylohydrazide ionophore attached to polyacrylamide with a nanomolar detection limit

Abstract

A durable sulfide selective solid-contact sensor based on a newly synthesized ceric complex of N′-acetyl-2-(benzothiazol-2yl)-3-(3-chloro-5-methyl-4H-pyrazol-4-yl)acrylo hydrazide (ABPAH) covalently attached to polyacrylamide (PAA) as the ionophore has been developed and potentiometrically evaluated. The all solid-contact sensor was constructed by the application of a thin film of the selective membrane cocktail onto the surface of a gold electrode, which was pre-coated with conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) as an ion and electron transducer. The cocktail was composed of poly(butyl methacrylate-co-dodecyl methacrylate) (PBDA) copolymer as a plasticizer-free matrix and the covalently attached acrylohydrazide ionophore. The sensor containing 12.5% of the Ce–ABPAH–PAA (ionophore II) showed a Nernstian slope of −29.42 mV per conc. decade with a linear range of 1.0 × 10⁻⁸–1.0 × 10⁻² mol L⁻¹ and a detection limit of 2.0 × 10⁻⁹ mol L⁻¹ in a sulfide anti-oxidant buffer (SAOB) solution with a pH value 13.0. The fast response time of >10 seconds for the proposed sulfide sensor allowed its utilization as a detector for the flow injection potentiometric (FIP) determination of sulfide ions in various water samples.