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Determination of Trace Amounts of Cr(III) in Presence of Cr(VI) by a Novel Potentiometric Membrane Sensor Based on a New Tridentate S,N,O Schiff's Base

Abstract The construction, performance characteristics, and application of a novel chromium(III) membrane sensor based on a new tridentates S,N,O Schiff's base 4-hydroxysalicylade-2-mercaptoanil (TSNO) are reported. The sensor was prepared by incorporating of TSNO, o-nitrophenyloctyl ether (NPOE), and sodium tetraphenylborate (NaTPB), into a plasticized poly(vinyl chloride) membrane. The sensor exhibits Nernstian response in the concentration range from 3.0 × 10−6 to 1.0 × 10−1 M with a detection limit of 1.5 × 10−6 M. It shows a very short response time (20 s). The electrode displays high selectivity towards chromium ion over several cations and can be used in a pH range 3.0–5.5. It was successfully applied to the determination of Cr(III) in wastewaters of chromium electroplating industries and as an indicator electrode in potentiometric titration of Cr(III) with EDTA and vice versa.