Great attention has been paid to the impact of heavy metals due to their abundance and presence in biological and environmental systems. Cr3+, among the heavy metals, employed for catalysts, leather tanning, glass, and paints is almost harmless. It is worth mentioning, Cr3+ has the major role in some metabolic processes. Therefore, there is a fundamental need to introduce a novel, efcient, selective, simple, and low-cost techniques for the determination of Cr3+. Herein, the poly (rutin)/carbon black-chitosan nanocomposite-modifed glassy carbon electrode (PRu/CB-Chi/GCE) was employed as a selective sensor for Cr3+ electrochemical determination using diferential pulse anodic stripping voltammetry (DPASV) technique. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), diferential pulse voltammetry (DPV), and feld emission scanning electron microscopy (FESEM) were performed to investigate the electrodes. According to optimal conditions, the linear range was achieved between 0.05 nM and 2000 nM with the detection limit (LOD) (S/N=3) obtained 0.016 nM. The modifed electrode was found to indicate the qualities of repeatability, reproducibility, selectivity, and stability ability. To demonstrate the applicability of the sensor, the modifed GCE was applied to detect chromium (III) ions in tap and river water samples with good recoveries of 91.54–103.17% – revealing that the sensor has suitable practicability toward Cr3+
