A modified hybrid silsesquioxane/histidine composite for copper and zinc adsorption and it behavior in the electro-oxidation of ascorbic acid.

Octa-(3-chloropropryl)silsesquioxane was chemically modified with histidine (SSQ-H) and characterized by spectroscopy in the infrared region (FT-IR), X-ray diffraction (XRD), X-ray Dispersive Energy Spectroscopy (EDX), Scanning Electron Microscopy (SEM). The analytical properties of SSQ-H were tested regarding of Cu and Zn adsorption and as an electrochemical sensor for the detection of ascorbic acid. The metal sorption results indicate that maximum amount of Cu and Zn adsorbed (Nf) were 1.58 × 10 and 5.67 × 10 mol g, respectively. After Cu and Zn ion adsorption and interaction with potassium hexacyanoferrate (III), the investigated materials displayed electroactivity for ascorbic acid detection. The anodic peak currents responses of a graphite paste electrode containing CuHCFSSQ-H presented a linear response in the concentration range of 4.0 × 10 to 4.0 × 10 mol L for ascorbic acid detection. The limit of detection was of 2.99 × 10 mol L, with an amperometric sensitivity of 1.69 μA/mol L. The intensity of the anodic peak currents of the graphite paste electrode containing ZnHCFSSQ-H in the concentration range of 9.0 × 10 to 9.0 × 10 mol L also displayed a linear response. The limit of detection was of 6.76 × 10 mol L, with an amperometric sensitivity of 0.0206 A/mol L.