Silica Gel Functionalized with 4‐Amino‐5‐(4pyridyl)‐4H‐1,2,4‐triazole‐3‐thiol and their Use as a Copper Sorbent and Electromediator for Voltammetric Detection of Ascorbic Acid

Abstract

Abstract In this work, the 3‐chloropropyl silica gel (SG) was prepared and organofunctionalized with 4‐amino‐5‐(4pyridyl)‐4H‐1,2,4‐triazole‐3‐thiol (SGA), that was characterized by infrared spectroscopy (FTIR) and cyclic voltammetry (CV). The cupric ions (Cu 2+ ) sorption on the silica functionalized surface (CuSGA) were performed in aqueous solution, at room temperature. It was performed a systematic study about voltammetric behavior of CuSGA, where the cyclic voltammogram of graphite paste electrode modified with CuSGA exhibited a single redox pair with formal potential ( E θ ′ )=0.30 V assigned to the process Cu + /Cu 2+ , (KCl 1.0 mol L −1 , v =20 mV s −1 ). The graphite paste electrode modified with CuSGA was sensitive to different concentrations of ascorbic acid and then an analytical curve could be constructed, with a linear response of 6.0×10 −6 to 9.0×10 −5 mol L −1 (R=0.9988) and a relative standard deviation of ±2.5 % ( n =3). The detection limit (3σ) and amperometric sensitivity were 4.78×10 −6 mol L −1 and 115.96 mA/mol L −1 , respectively.