Development of a novel electrochemical sensor for the detection of U6+ ion with polyaniline, N-phenylglycine and graphene oxide based electrode using 2-(5-bromo-2-pyridylazo)-5-(diethylamino) phenol as ligand

Low limit of detection (LOD), high sensitivity and selectivity are essential performance criteria of a sensor. As the naturally occurring uranyl ion (U⁶⁺) is toxic, a sensor with suitable performance parameters for measuring U⁶⁺ in drinking water is of interest. In this work, four aspects of the detection of U⁶⁺ are presented. First, a composite synthesized from aniline, N-phenylglycine and graphene oxide (GO) was used for the first time to detect the uranyl ion. Second, the ligand 2-(5-bromo-2-pyridylazo)-5-(diethylamino) phenol (BromoPADAP) was used as a ligand, attached at the composite surface, functionalized with diamine (Design I) and also as a complexing agent in the electrolyte (Design II), and a comparative study for both the cases was conducted. The parameters for comparison were the sensitivity, LOD and interference from several test ions. It was found that for Design I, the LOD was 50 ppt, while for Design II the LOD was 8 ppb. Next, the interference phenomena were explained by the conventional peak reduction (PR) technique and the barrier width (BW) technique. The BW technique was used for the first time to scale the interference of test ions toward the target analyte Cd²⁺, as in our previous works. PR technique requires a higher number of tests, while the BW technique employs a couple of tests, thus minimizing the effort. In this work, the BW technique supported the PR technique results in predicting the interference behavior. Finally, the BW technique was used to explain the difference in Design I and II results.

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