Sunset Yellow-Cu(II) Complex: DFT-supported electrochemical investigation and determination of Cu(II) ions in human serum and artificial sweat

A new, low-cost, outstanding, effortless, and disposable platform based on activated pencil graphite electrode and Sunset Yellow-Cu(II) complex (233 % increase in peak height compared to the oxidation of free Cu(II) ions) was applied for the determination of Cu(II) ions in human serum and artificial sweat samples. The complex characteristics were examined for the first time using electrochemical (cyclic voltammetry), spectrophotometric and density-functional theory (DFT) studies. The peaks, which increased with the oxidation of the complex at -40 mV and decreased with the complexation of free Sunset Yellow with Cu(II) ions at 600 mV, were used as the analytical signals for the determination of Cu(II) ions in the presence of pH 10 borate buffer solution. The suggested method has the capability to detect Cu(II) ions at a low concentration of 55 nM, with broad linear ranges from 0.18 to 27 mu M based on the oxidation of free sunset yellow, and from 2.38 to 100 mu M based on the oxidation of the complex. Additionally, the proposed electrochemical system demonstrates exceptional stability, selectivity, and accuracy for detecting Cu(II) ions in biological samples.