Simultaneous Trace Electrochemical Determination of Xanthine Theophylline and Theobromine with a Novel Sensor Based on a Composite Including Metal Oxide Nanoparticle Multi-walled Carbon Nanotube and Nano-Na-montmorillonite Clay

We report the simultaneous determination of purine molecules with biological significance on pencil graphite electrode (PGE) modified with a composite solution including NiO nanoparticles, multi-walled carbon nanotube (MWCNT), and natural nano-Na-montmorillonite clay (NNaM) using DPV technique. The novel sensor, NiO/MWCNT/NNaM/PGE, achieved simultaneous determination of xanthine, theophylline, and theobromine at the detection limits 0.077 mu M, 0.361 mu M, and 0.458 mu M with the linear working ranges 0.5-150 mu M, 5-200 mu M, and 5-250 mu M in Britton-Robinson buffer at pH 2.0, respectively. The sensor revealed excellent performance for the simultaneous determination of XT, TP, and TB in three real-world samples.