The utility of carbon as the base material for carbon paste electrodes has been considered for many years. In this work, we were applied MWCNT as a modifier and Schiff base chitosan and 5-nitro isatin as ionophore along with carbon. Prepared CPE shows a Nernstian response of 29.567 mV per decade in a wide linear dynamic range of 1.0 × 10-5 to 1.0 ×10-1 M for Mg2+ ion. The optimization process had performed by Mixture design in design expert software. This present sensor has a short time of response of about 10 s. The applicable pH range was obtained 3.51-9.0 and Detection limit was calculated 1.4 ×10-5 M. Lastly, the prepared sensor was used in the indirect potentiometry (potentiometric titration) as an indicator or working electrode. The data obtained from the experiments showed that the electrode is usable in analytical applications. تفاصيل المقالة