Chemically modified copper potentiometric sensors based on curcumin and amino acid

Abstract

Modified carbon paste electrodes based on amino acid (l-ornithine) or curcumin (turmeric) as ionophores and o-nitrophenyl octyl ether (o-NPOE) as solvent mediator were prepared and investigated as Cu(II) ion-selective electrodes. The reaction mechanism between Cu(II) and l-ornithine (electrode I) or turmeric (electrode II) ionophores at the sensor surface were studied using energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM) and IR spectra measurement. These electrodes showed potentiometric response with a divalent cationic Nernstian slopes of 29.0 ± 0.04 and 30.4 ± 0.01 mV decade−1, within a working concentration ranging from 1.0 × 10−6 to 1.0 × 10−2 mol L−1 with a short response time of 10 and 7 s for electrodes I and II, respectively. The electrodes exhibited constant potentiometric response in pH range 2-6 and 3-6 for electrodes I and II, respectively. The proposed sensors exhibited adequate sensitivity to Cu(II) ions over the other metal ions. The sensors were used for estimation of Cu(II) ion concentration in real water samples with satisfactory and good reproducibility results.