Monday, 2 October 2017: 10:40
Chesapeake J (Gaylord National Resort and Convention Center)
A combination of thermal vaporization and solid phase extraction were used with a variety of different electrochemical methods for the analysis of phenolic molecules in plant materials. The direct electrochemical oxidation of the phenols using square wave voltammetry showed good linearity and adequate sensitivity, provided that freshly polished electrodes were used for each measurement. The oxidation of the phenol created a reactive product that quickly fouled the surface of the electrode and limited the method to the use of fresh electrode surfaces. The results obtained with this method are well correlated with GC analysis of the same samples. If fresh electrodes are not easily obtained, then an indirect electrochemical approach seems a realistic alternative. Although some fouling was observed, the indirect method had sufficient sensitivity and linearity to be useful for these measurements. The use of both fresh electrode surfaces, as well as indirect electrochemical detection, produced improved correlations with the spiked concentrations. This is likely due to the improved fidelity of the measurement, since a fresh surface is used each time and a minimum amount of fouling is produced by the measurement. The combination of these approaches will be used to produce a sampling tool and sensor array for the characterization of a variety of commercial agricultural products.