Pseudo-graphite from the University of Idaho known as GUITAR (pseudo-graphite from the University of Idaho thermolyzed asphalt reaction), is a nanocrystalline pseudo-graphite, shows morphological features similar to that of graphite, including basal and edge planes. Unlike graphite and other sp2 and sp3 hybridized carbons, GUITAR possesses both fast heterogeneous electron transfer kinetics and high corrosion resistance. In this study basal plane GUITAR electrodes were examined as a sensor for salicylic acid using square wave voltammetry (SWV) in 0.1 M phosphate buffer solution at pH 7.0. Utilizing SWV at a step potential of 10 mV, amplitude 50 mV, and frequency 100 Hz, GUITAR was found to have a limit of detection of 1.0 µM, linear range of 1-4500 µM, sensitivity of 581 µA·mM-1·cm-2 and a signal stability for > 50 measurements. A surface regenerative pulse of +1.0 V for 3 min was applied in 0.1 M phosphate buffer solution, pH = 7.0 after each measurement to clean the salicylic acid passivation layer from the GUITAR surface. The common interfering ions Na+, K+, NO3-, SO42-, Cl-, boric acid, ethanol and ascorbic acid did not affect the response of the GUITAR-based sensor. The combination of limit of detection, linear range, sensitivity, sensor lifetime and its relative lack of interferences indicate that GUITAR is one of the best performers for sensing salicylic acid.
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