Simultaneous determination of theobromine, theophylline, and caffeine using a modified electrode with petal-like MnO₂ nanostructure

This study substantially synthesized the β-type MnO₂ nano-flowers assembled by the hierarchical nano-sheets using a simplified hydro-thermal procedure. According to the FESEM images, MnO₂ nano-flower exhibited diameter of ∼800 nm and fabricated with a lot of irregular sheets as a petal-like structure with thickness of several nano-meters. Therefore, the study focused on the construction of an electro-chemical sensor to simultaneously determine theobromine (ThB), theophylline (ThP), as well as caffeine (CaF) on the basis of the β-type hierarchical structure of the MnO₂ nano-flowers (βH-MnO₂-NF) modified electrode (βH-MnO₂-NF/GCE). Analysis showed an acceptable linear association between the oxidation peak current and ThB, ThP and CaF concentration within the ranges between 0.01 and 320.0 μM with a limit of detection (LOD) equal to 8.7, 5.9, and 10.1 nM (S/N = 3), respectively. Additionally, this study intended to investigate ThB, Thp and CaF bio-availability in the five commercially available brands of the chocolate products and drug.