Determination of Chromium(III) and Magnesium(II) Ions in Pharmacological and Real Water Samples using Potentiometric Sensors based on Chitosan Schiff base Derivative as Green and Sensitive Ionophore

In the study, novel and sensitive carbon paste electrodes (CPEs) developed for the potentiometric measurement of Cr(III) and Mg(II) ions in pharmacological and water samples. CPEs as indicator electrodes were prepared from a mixture of four components, including graphite powder, paraffin oil, multi-walled carbon nanotubes (MWCNTs), and a green ionophore (Chitosan Schiff base derivative). Optimization of CPE composites indicated that the critical factor in the preparation of the CPEs was chitosan Schiff base derivative which selectivity proposed sensors highly depended on this factor. Effects of various parameters such as pH, lifetime, response time, and selectivity of the potentiometric sensors to determine Cr(III) and Mg(II) ions were also evaluated. The results indicated that the proposed sensors can be applied in a relatively wide range of pH, long lifetimes, short response times, and excellent selectivity for the analyte determination. The prepared sensors show Nernstian slopes of 19.53 and 29.83 mVdecade−1, and LODs of 5.6×10– 8 and 4.4×10−9 with RSDs lower than 2.3% for Cr(III) and Mg(II) ion determination, respectively. The calibration curves were linear in the concentration ranges of 1.0×10-7-1.0×10-2 and 1.0×10-8-1.0×10-3 M, and R-square of 0.989 and 0.987 for the measurement of Cr(III) and Mg(II) ions, respectively. Besides, the sensors were successfully utilized for the Cr(III) and Mg(II) ion measurement in real samples such as tablet and tap water samples with suitable recovery higher than 97.6%.