Organically nanoporous silica gel based on carbon paste electrode for potentiometric detection of trace Cr(III) Original Research Article

A new ion-selective electrode (ISE) for the detection of trace chromium(III) was designed by using 2-acetylpyridine and nanoporous silica gel (APNSG)-functionalized carbon paste electrode (CPE). The presence of APNSG acted as not only a paste binder, but also a reactive material. With 7.5 wt% APNSG proportions, the developed electrode exhibited wide dynamic range of 1.0 × 10−8 to 1.0 × 10−3 M toward Cr(III) with a detection limit of 8.0 × 10−9 M and a Nernstian slope of 19.8 ± 0.2 mV decade−1. The as-prepared electrode displayed rapid response (∼55 s), long-time stability, and high sensitivity. Moreover, the potentiometric responses could be carried out with wide pH range of 1.5–5.0. In addition, the content of Cr(III) in food samples, e.g. coffee and tea leaves, has been assayed by the developed electrode, atomic absorption spectrophotometer (AAS) and atomic emission spectrometer (ICP-AES), respectively, and consistent results were obtained. Importantly, the response mechanism of the proposed electrode was investigated by using AC impedance and UV–vis spectroscopy.