Application of a Fully 3D Printed Carbon Electrode for the Double Potential Step Chronocoulometric Determination of 2,4dinitrophenol in Environmental Water Samples

This paper demonstrates the application of a fully 3D printed carbon nanofiber–graphite–polystyrene working electrode for the double potential step chronocoulometric determination of 2,4-dinitrophenol in an environmental water sample. Initial cyclic voltammetric investigations were undertaken to characterise the redox behaviour of 2,4-dinitrophenol over the pH range 2 to 8. On the initial negative-going scan, two reduction peaks were recorded and concluded to result from the reduction of the two nitro groups to their corresponding hydroxylamines. On the return positive-going scan, two oxidation peaks were recorded resulting from the oxidation of the hydroxylamine formed on the initial negative scan. All peaks were found to be pH dependent over the range studied. Using a double potential step chronocoulometric approach (step 1 = -1.4 V; step 2 = +0.8 V), a calibration plot was constructed and found to be linear from 50 µM to 1.0 mM (R2= 0.9978) with a detection limit of 7.8 µM (based on a signal-to-noise ratio of 3). The method was evaluated by carrying out 2,4-dinitrophenol determinations on a fortified and unfortified environmental water sample. Using external calibration, a mean recovery of 106 % was obtained with an associated coefficient of variation of 3.6 % calculated for a concentration of 50 µM. The results show that these 3D printed electrodes are a promising alternative to electrodes fabricated using traditional materials and that reliable data may be obtained for 2,4-dinitrophenol in environmental water samples.