MnO 2 ‐TiO 2 Nanocomposite and 2‐(3,4‐Dihydroxyphenethyl) Isoindoline‐1,3‐Dione as an Electrochemical Platform for the Concurrent Determination of Cysteine, Tryptophan and Uric Acid

A novel modified carbon paste electrode (CPE) based on an MnO 2 ‐TiO 2 nanocomposite and 2‐(3,4 dihydroxyphenethyl) isoindoline‐1,3‐dione (DPID) as the modifier for the simultaneous analysis of cysteine (Cys), tryptophan (Trp) and uric acid (UA), as three key biochemicals present in human body. The MnO 2 /TiO 2 nanocomposite was synthesized through a chemical co‐precipitation approach and the resulting electrode (MnO 2 ‐TiO 2 /DPID/CPE) was used for studying the electrochemical oxidation of cysteine (Cys), tryptophan (Trp) and uric acid. As opposed to conventional CPEs, the oxidation peak potential of cysteine on MnO 2 ‐TiO 2 /DPID/CPE had a 600.0 mV decrease in overpotential and could be observed at 30.0 mV, and the signals were linear from 0.025 to 200.0 μM, and a lower detection limit of 0.013 μM was reached. The MnO 2 ‐TiO 2 /DPID/CPE was satisfactorily used for the concurrent analysis of Cys, Trp and UA in pharmaceutical and biological samples.