Document Type : Original Research Article

Authors

• Maryam Pirozmand
• Azizallah Nezhadali
• Mahmood Payehghadr
• Lotfali Saghatforoush

Department of Chemistry, Payame Noor University, 19395-4697 Tehran, Iran

Abstract

A novel chemically modified carbon paste electrode (CMCPE) impregnated with 4′-(4-chlorophenyl)-2,2′:6′,2′′-terpyridine ligand was prepared and applied for voltammetric determination of Cd²⁺ ion in petrochemical samples. The effects of pH, ligand amount and supporting electrolyte on the selective adsorption properties for the Cd²⁺ ion were explored. The sensor displayed substantially good resistance against interfering agents. In the presence of a large excess of Na⁺, K⁺, Ca²⁺, Mg²⁺ and Pb²⁺, the adsorption capacity for Cd²⁺ was slightly changed, suggesting the high selectivity of CMCPE for Cd²⁺ions. The parameters controlling the response of the electrode were investigated. The limit of detection (LOD) and  relative standard deviation (n = 5) were obtained by 3.77 ng/Land 0.45%, respectively. The preconcentration procedure revealed a linear curve within the concentration range of 4 – 3000 ng/L and a good linearity with squared correlation coefficient of (R²) 0.9988 was achieved. The CV was run starting from –1.5 V to 0.0 V and back (Scan rate: 100 mV/s). The best ratio of the Cd²⁺-Ligand in carbon paste was 8% (w/w) for a good detection of Cd²⁺ ions. Optimum pH for maximum adsorption was 4.0 ±0.2. All the instrumental parameters involved in the analytical procedure were optimized. The study was accomplished in Britton–Robinson (B-R) buffer solution of 2 ng/mL Cd²⁺ ions. The optimal values of scan rate, pulse amplitude, pulse time, voltage step, voltage step time, deposition potential and deposition time were obtained 100 mV/s, 0.20 V, 0.04 s, 0.005 V, 1.2 s, – 0.95 V and 150 s, respectively.

Graphical Abstract

Keywords

• Sensor
• carbon paste electrode
• ion selective electrode
• cadmium
• voltammetry

Main Subjects

• Analytical chemistry