Enhanced sensitivity of 4-chlorophenol detection by use of nitrobenzene as a liquid membrane over a carbon nanotube-modified glassy carbon electrode

The analytical utility of nitrobenzene as a liquid membrane for the detection of hydrophobic compounds was examined with a glassy carbon electrode, using 4-chlorophenol as the model analyte. Electrochemical experiments indicated a large partition coefficient for the entry of 4-chlorophenol into the nitrobenzene (7.6 x 10(2) +/- 1.5 x 10(2)). This was combined with an increase in effective electrode area by coating with single-walled nanotubes. Differential pulse voltammetry produced a linear response across the range 0.3 nM to 1.5 nM with a sensitivity of 1.1 x 10(-5) A nM(-1) cm(-2). To the best of our knowledge, this limit of detection for phenol is lower than other nonenzymatic modifications of carbon.