Novel Plastic Chromium(III)‐Ion Selective Electrodes Based on Different Ionophoric Species and Plasticizing Solvent Mediators

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Abstract
Different ionophoric species, viz.: 18‐crown‐6 (18C6), dibenzo‐18‐crown‐6 (DB18C6) and calix[6]arene (CAX), as electroactive materials, with 2‐nitrophenyloctylether (2‐NPOE), bis(ethylhexyl)sebacate (DOS), dioctyl phthalate (DOP), and didecyl phthalate (DDP) as plasticizing solvent mediators were used to construct Cr3+ selective electrodes in a PVC matrix in the ratio (w/w) PVC: ionophore: plasticizer (60 : 2 : 120). Seven electrodes out of the fabricated 12 electrodes, gave best results in terms of working concentration range (1.0×10−5−1.0×10−1 M) with a close to Nernstian slope of 18.5 and a Nernstian slope of 20.0 mV/decade of activity. The usable pH range of the sensors is 4.0–7.0. The detection limit of the selected electrodes is ≤1.0×10−7 M. The response time of the sensors is 8–35 s, depending on the concentration of Cr3+ used. The selectivity coefficient values indicate that the electrodes are highly selective for Cr3+ over a number of other cations except Pb2+ and Na+ (for some electrodes). The electrodes have successfully been used to determine Cr3+ in certified and real alloys and in effluents of electroplating shops with a precision as relative standard deviation (RSD)3+‐ion selective electrodes. The results obtained by the proposed ISEs are in good agreement with the results obtained by direct flame AAS method.