Anodic stripping voltammetric determination of copper (II) ions using agraphene quantum dot Modified pencil graphite Electrode

Copper is essential to all living organisms as a trace nutritional mineral because it involves in thesynthesis of hemoglobin, a variety of enzymes, and the metabolism of the body [1-3]. However,copper deficiency or elevated levels of copper can bring about opposite health effects. Due tophysiological importance of copper and widely usage of it in industrial and agricultural sectors,determination of copper in various matrices is very important and numerous analytical techniqueshave been used for the accurate and sensitive determination of trace quantities of copper [4-10].Among these, electrochemical techniques have attracted extra attention because of manyadvantages such as simplicity, cost effectiveness, small instrumentation and etc. Graphenequantum dots (GQDs), a new kind of carbon nanomaterials, with great surface area and quickelectron transfer ability are one of the best electrode modifiers which can increase the rate ofelectrochemical reactions and attracted more attention as electrode modifier [11]. Recently, Wanget. al developed graphene quantum dots as a fluorescent sensing platform for highly efficientdetection of copper (II) ions [12]. In this work, we described a simple and sensitiveelectrochemical approach for the determination of low concentration of Cu2+ ions using GQDmodified pencil graphite electrode by square wave adsorptive stripping voltammetric method.The sensing mechanism could be attributed to the formation of complex between Cu2+ ions andoxygen containing groups in GQDs which result in increased SWV signal compared to bareelectrode. Optimization of various experimental parameters such as pre-concentration time, preconcentrationpotential, pH, and buffer type which influenced the performance of the sensor, wereinvestigated. Under optimized condition, GQD modified electrode was used for the analysis ofCu2+ in the concentration range from 0.05 to 4 nM, and a lower detection limit of 0.012 nM with good stability, repeatability, and selectivity. Finally, the practical applicability of GQD-PGE wasconfirmed via measuring trace amount of Cu (II) in water samples. The GQD-PGE surface couldbe regenerated by exerting more positive potential than the stripping potential of the Cu (II) ionand then used for another deposition. This is the first usage of untreated graphene type nanoparticles, GQD, for the simple, cheap, sensitive and selective determination of copper ions withexcellent performance and low detection limit.

کلیدواژه ها:

Graphene quantum dot ، Electrochemical detection ، Cu (II) ions ، Adsorptive strippingvoltammetry