In this contribution, a very simple and reliable strategy based on the easy modification of a glassy carbon electrode (GCE) by pre-electrolyzing GCE in ammonium carbamate aqueous solution was employed for the simultaneous determination of hydroquinone (HQ) and catechol (CC). Compared with bare GCE, the incorporation of nitrogen into the GCE surface structure improved the electrocatalytic properties of GCE towards the electro-oxidation of HQ and CC. The nitrogen-introduced GCE (N-GCE) was evaluated for the simultaneous detection of HQ and CC and the linear ranges for HQ and CC were both from 5 to 260 μM. Their detection limits were both evaluated to be 0.2 μM (S/N = 3). The present method was applied for the determination of HQ and CC in real river water samples with recoveries of 95.0–102.1%. In addition, a possible detection mechanism of HQ and CC was discussed.

In this study, we demonstrate a sensitive nitrite detection method using a simple electrochemically aminated glassy carbon electrode (AGCE). The AGCE exhibits a much enhanced sensitivity and good electrochemical response towards nitrite oxidation over a linear range from 0.08 to 1010 μM with a detection limit of 0.01 μM. The validity of the AGCE for real samples was evaluated by determining nitrite in river water and rain water. The good electrochemical performance, construction simplicity and cost-effective functional process of the glassy carbon electrode make the proposed method promising for sensing applications for environmental monitoring. A possible mechanism for the electrocatalytic oxidation process of nitrite is suggested and the kinetics of the catalytic oxidation of nitrite were investigated.