An impedimetric approach for determination of ammonium using silver/poly-1-aminoanthraquinone/carbon paste electrode

Here, we present the electrochemical determination of ammonium in water samples, emphasizing the importance of accurate and precise assessment of its concentration. The modified electrode used in this study was fabricated through the anodic polymerization of 1-aminoanthraquinone (1-AAQ) and deposition of silver particles into a carbon paste electrode. The fabrication process involved cyclic voltammetry in a 0.1 M HCl solution, followed by the application of a potential of 0.2 V for 75 s. The resulting Ag/poly-1-AAQ/CPE exhibited remarkable electrochemical properties, as confirmed by scanning electron spectroscopy (SEM), energy-dispersive X-ray analysis (EDX), and elemental mapping. The successful deposition of silver at percentages of 12.07% on Ag/CPE and 0.75% on Ag/poly-1-AAQ/CPE was observed. The Ag/poly-1-AAQ/CPE was employed for impedimetric determination of ammonium in a solution of 0.1 M Na₂SO₄. The charge transfer resistance) output from the fitting of the experimental impedimetric data of ammonium determination exhibited good linearity over a concentration range of 5 µM to 200 µM NH₄⁺, with a detection limit of 3.3 µM NH₄⁺. The precision of the modified electrode over ten replicate measurements were conducted at three concentration levels (a low of 5 µM NH₄⁺, a medium of 50 µM NH₄⁺, and a high of 200 µM NH₄⁺). The obtained relative standard deviation (RSD) values of 18%, 12% and 7%, respectively, indicating good precision.