Sensitive voltannnetric response of p-nitroaniline on single-wall carbon nanotube-lonic liquid gel modified glassy carbon electrodes

An ionic liquid (i.e., 1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6)-single-walled carbon nanotube (SWNT) gel modified glassy carbon electrode (BMIMPF6-SWNT/GCE) is fabricated. At it the voltammetric behavior and determination of p-nitroaniline (PNA) is explored. PNA can exhibit a sensitive cathodic peak at -0.70 V (vs. SCE) in pH 7.0 phosphate buffer solution on the electrode, resulting from the irreversible reduction of PNA. Under the optimized conditions, the peak current is linear to PNA concentration over the range of 1.0 X 10(-8) -7.0 x 10(-6) M, and the detection limit is 8.0 x 10(-9) M. The electrode can be regenerated by successive potential scan in a blank solution for about 5 times and exhibits good reproducibility. Meanwhile, the feasibility to determine other nitroaromatic compounds (NACs) with the modified electrode is also tested. It is found that the NACs studied (i.e., p-nitroaniline, p-nitrophenol, o-nitrophenol, m-nitrophenol, p-nitrobenzoic acid, and nitrobenzene) can all cause sensitive cathodic peaks under the conditions, but their peak potentials and peak currents are different to some extent. Their peak currents and concentrations show linear relationships in concentration ranges with about 3 orders of magnitude. The detection limits are 8.0 x 10(-9) M for p-nitroaniline, 2.0 x 10(-9) M for p-nitrophenol, 5.0 x 10(-9) M for o-nitrophenol, 5.0 x 10(-9) M for in-nitrophenol, 2.0 x 10(-8) M for p-nitrobenzoic acid and 8.0 x 10(-9) M for nitrobenzene respectively. The BMIMPF6-SWNT/GCE is applied to the determination of NACs in lake water.