Simplified electrochemical sensor based on sulphuric acid-preactivated glassy carbon electrode for enhanced detection of 2-nitrophenol and 4-aminopyridine

Steadily increasing water pollutants pose significant health risks; hence, environmental contaminants detection is a societal imperative. In response to growing ecological concerns, electrochemical sensors qualify as environmentally relevant tools. This report presents an electrochemical approach of pre-anodizing with H<inf>2</inf>SO<inf>4</inf> to develop a pre-treated glassy carbon electrode sensor (PGCE) to identify eco-toxic organic pollutants 2-nitrophenol and 4-aminopyridine in water bodies. The suggested process enhanced sensitivity after pretreatment with 1 M H<inf>2</inf>SO<inf>4</inf> and cycling from -0.4 V to + 2.0 V over 20 cycles. The electrochemical characteristics of the aforesaid pollutants were analyzed individually through cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods and compared with the data obtained using an unmodified bare glassy carbon electrode (BGCE). An enhancement of the cyclic voltammetric response of well-defined anodic and cathodic peaks at 0.66 V and 0.31 V, respectively, for 2-nitrophenol and only an anodic peak at -0.60 V for 4-aminopyridine was observed. For both the pollutants, the peak current elevated with increasing concentration from 0.25 to 1.00 µM and scan rate varied from 10 to 50 mVs-1, indicating diffusion-controlled electrode activity. Through DPV, the limit of detection (LOD) for 2-nitrophenol was 3.46 µM, and the limit of quantification (LOQ) was reported to be 10.49 µM, whereas LOD and LOQ were 0.89 µM and 2.70 µM, respectively, for 4-aminopyridine. The reported sensor provides excellent stability, selectivity, reproducibility, and good reactivity towards the detection of organic pollutants and hence finds a good number of applications in environmental studies.