Electrochemical sensing of caffeine in real-life samples and its interaction with calf thymus DNA

This paper presents a bare pencil graphite electrode (bPGE) utilized for the electrochemical determination of caffeine (CAF). The electrochemical behavior of CAF was examined with the cyclic voltammetry technique. The oxidation of CAF is an irreversible and diffusion-controlled mechanism on the bPGE surface. The 0.1 M H 2 SO 4 solution produced the highest oxidation peak currents of CAF using differential pulse (DPV) and square wave (SWV) voltammetry techniques. The pH of the H 2 SO 4 solution was examined to determine its optimum value. The pH 1.0 value obtained the highest peak currents with both techniques. DPV and SWV methods achieved electrochemical determination of CAF with 30.0–1000.0 µM, and 10–1000 µM linear working ranges, respectively. LOD values for DPV and SWV techniques are 8.84 µM, and 9.36 µM, respectively. The developed methods were tested with real samples (cola and energy drink) and interference studies. DPV and SWV methods achieved real sample analysis with recovery values of between %95.6 and %103.8. Besides, the DNA binding constant of CAF was scanned via the in-solution method with both techniques. The calculated binding constants for DPV and SWV are 4.52 × 10 3 M −1 and 8.64 × 10 3 M −1 , respectively, indicating that the interaction between DNA and CAF is facilitated by weak electrostatic forces. Graphical abstract