Electrochemical study of 5-nitroquinoline using carbon film electrode and its determination in model samples of drinking and river water

This work is focused on the determination of submicromolar concentrations of 5-nitroquinoline (5-NQ) using differential pulse voltammetry (DPV) and direct current voltammetry (DCV) at a novel type of carbon film electrode (CFE). The advantages of CFE are its wide potential window in both cathodic and anodic regions (ca 3 V span), high sensitivity, and low noise of measurements. The other advantages of CFE are the possibility to quickly and easily renew the electrode surface and also non-toxicity for environment compared to mercury electrodes. Calibration dependences in deionized water are linear from 0.4 to 100 μmol dm^-3, with limit of quantification (LOQ) 1 μmol dm^-3 using DCV, and from 0.2 to 100 μmol dm^-3, with LOQ 0.4 μmol dm^-3 using DPV. The DPV method was verified for model samples of drinking and river water. The calibration dependences were linear in the concentration ranges from 0.2 to 10 μmol dm^-3 for both matrices, with LOQ 0.2 μmol dm^-3 for drinking water and LOQ 0.6 μmol dm^-3 for river water, respectively. This work has proved the usability of CFE for submicromolar determination of 5-NQ based on cathodic reduction of the present nitro group.