Incorporating a Novel Hexaazatriphenylene Derivative to a Flexible Screen-Printed Electrochemical Sensor for Copper Ion Detection in Water Samples

A novel hexaazatriphenylene derivative, 6,7,16, 17,26,27-hexahydronaphtho[2,3-h]naphtho[2',3':7,8] quinoxalino[2,3-a]naphtho[2',3':7,8] quinoxalino[2,3-c]phenazine-5, 10,15,20,25,30-hexaone (HNQP), was successfully synthesized to selectively detect copper (Cu ²⁺ ) ions over other metal ions in aqueous solutions. A flexible and planar electrochemical sensor with silver, carbon and silver/silver chloride as counter, working and reference electrodes, respectively was fabricated on a polyimide substrate using an additive screen printing process. The HNQP was drop casted on the electrochemical sensor and its capability to selectively detect Cu ²⁺ ions was investigated by performing differential pulse voltammetry (DPV). A wide peak domain with average currents increasing from 0.16 μA to 17.97 μA was observed as the concentration of Cu ²⁺ ions was increased from 0 μM to 100 μM, respectively, at reduction potential ~0.05V. A sensitivity of 135 μA/mM and a correlation coefficient of 0.99 was calculated for the HNQP drop casted electrochemical sensor. Further tests revealed selective detection of Cu ²⁺ ions over other interfering metal ions including Co ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ²⁺ , Li ¹⁺ , Pb ²⁺ , Hg ²⁺ and Ag ¹⁺ using the HNQP drop casted electrochemical sensor. In addition, a limit of detection (LOD) and limit of quantification (LOQ) of 142 nM and 430 nM, respectively, was calculated for the sensor which is lower than the specified toxicity levels of Cu ²⁺ ions in drinking water (20 - 30 μM) set by the U.S. environmental protection agency (EPA) and world health organization (WHO).