Synthesis and Spectroscopic Characterization of an Unusual Succinylated Starch Applied to Carbon Paste Electrodes

Abstract

This work presents the structural characterization of an unusual modified starch with succinic anhydride (2% w/v). The product characterized by infrared spectroscopy shows the carbonyl group band in 1724 cm−1, while the 13C NMR spectrum shows two signals in 174.71 and 31.61 ppm associated with the carbonyl and methylenic carbons from the symmetric succinyl group (OCOCH2CH2OCO). These analyses indicate a cross‐linked structure for the modified starch (CL starch). This product is used as a chemical modifier in carbon paste electrodes (CPE). Cyclic voltammetry and electrochemical impedance spectroscopy analyses show that the cross‐linked starch improves the electrochemical performance of the electrodes, since higher peak currents, lower charge transfer resistance values. Also, the increase in the CL starch proportion in CPE results in a higher current intensity for all proportions tested. This behavior can be attributed to decrease in hydrophilic character of the electrode material after the CL addition, which results in a lower capacitive behavior and a higher faradaic current. Among all the modified CPE, the one with 5% w/w CL per graphite proportion shows the best electrochemical features, suggesting its potential application as an electrochemical sensor for the detection of different chemical species of environmental and biological relevance.

Starch-Based Electrochemical Sensors and Biosensors: A Review

“…Sayka et al [ 124 ], described the synthesis of an unusually modified starch (CL starch), employing succinic anhydride, and evaluated if the proposed starch influenced the electrochemical response of carbon paste electrodes The mixture was homogenized, and the carbon paste formed (CPE/CL) was packed into the cavity of a Teflon tube provided with a copper electrical contact. More promising electrochemical features were obtained using CL starch than bare CPE or CPE containing unmodified starch, attributed to the lower hydrophilic character presented by CPE/CL, resulting in a lower background current.…”