Glassy carbon electrode modified with a layer of single-walled carbon nanotube and polypyrrole doped with new coccine: Application to the sensitive electrochemical determination of Salbutamol

Carbon nanotubes (CNTs), discovered by lijima in 1991 [1], have attracted the attention of scientists in many research fields such as chemistry, physics and material science, due to their extraordinary structural, mechanical, chemical and electronic properties. CNTs display high electrical conductivity, high surface area, good mechanical strength, high elasticity and tensile strength and excellent thermal and chemical stability [2]. Conducting polymers (CPs) are conjugated polymers, which have similar electronic properties (magnetic, conductivity and optical) to metals, while retaining properties of conventional organic polymers [3].A promising electrochemical sensor was developed based on a layer by layer process by electropolymerization of pyrrole in the presence of new coccine (NC) as dopant anion on the surface of the single-walled carbon nanotubes (SWCNTs) pre-coated glassy carbon electrode (GCE). The modified electrode was used as a sensitive electrochemical sensor for voltammetric determination of salbutamol (SAL). The electrochemical behavior of SAL was investigated on the surface of the modified electrode using linear sweep voltammetry (LSV). The results showed a remarkable increase (∼60 times) in the anodic peak current of SAL in comparison to the bare GCE for 5 µM SAL. The effect of experimental variables such as, drop size of the casted SWCNTs suspension, pH of the supporting electrolyte, accumulation conditions and the number of cycles in the electro-polymerization process on the electrode response was investigated. Under the optimum conditions, the modified electrode showed a wide linear dynamic range of 0.04-0.1 µ mol L−1 and 0.1-1 µ mol L−1 with a detection limit of 1.3 nmol L−1 for the voltammetric determination of SAL. The prepared electrode showed high sensitivity, stability and good reproducibility in response to SAL. This sensor was successfully applied for the accurate determination of trace amounts of SAL in pharmaceutical and clinical preparations.