Sensitive determination of iodide at graphitic carbon nitride-chitosan composite modified screen-printed electrode in urine and salt using cathodic stripping voltammetry

Abstract

Iodide is an important constituent in various biological processes; hence its determination is important. A simple voltammetric method has been investigated for iodide determination using disposable screen-printed electrode modified with graphitic carbon nitride-chitosan composite (gCN-Chit/SPE). The sensor presented excellent electrocatalytic response towards iodide sensing. The SEM analysis of the modified electrode showed a rough and sheet like morphology. The EDX analysis showed the high content of nitrogen elements in the composite layer of the modified electrode which is crucial for iodide ion sensing. Various parameters such as electrolyte concentration, deposition potential, deposition time etc. were optimized for iodide sensing. The use of low concentration of electrolyte favored the electro-oxidation of iodide. Under the suitable experimental conditions, the gCN-Chit/SPE exhibited good linear performance for iodide in the concentration range from 0.075 to 200 µM with a regression coefficient (R2) of 0.9946 and the limit of detection (LOD) of 0.01 µM. The electrode presented interference free effect for iodide in the presence of relatively high concentration of other substances. The sensor was applied to determine iodide in real samples such as urine, tap water and table salt. In real sample analysis good recoveries in percent was achieved using the developed electrode. Further, the composite layer at the electrode surface provided good mechanical stability and thus could be reused for several determinations. The results confirmed that the design electrochemical sensor could be successfully employed for real sample applications with highly sensitive iodide determination.