Gold Nanoparticle Chemiresistor Sensor Array that Differentiates between Hydrocarbon Fuels Dissolved in Artificial Seawater

Gold nanoparticle films (Au-NPF) functionalized with a range of hydrophobic and hydrophilic thiols were assembled in chemiresistor sensor arrays that were used to differentiate between complex mixtures of analytes in the aqueous phase. A chemiresistor array sampled a simple system of linear alcohols (methanol, ethanol, propan-1-ol, and butan-1-ol) dissolved in water over a range of concentrations. Discriminant analysis confirmed that the response patterns of the array could be used to successfully distinguish between the different alcohol solutions at concentrations above 20 mM for all of the alcohols except methanol, which was distinguished at concentrations above 200 mM. Alcohol solutions more dilute than these concentrations had response patterns that were not consistently recognizable and failed cross validation testing. This defined the approximate limit of discrimination for the system, which was close to the limits of detection for the majority of the individual sensors. Another Au-NPF chemiresistor array was exposed to, and successfully identified crude oil, diesel, and three varieties of gasoline dissolved in artificial seawater at a fixed concentration. This work is a demonstration that the pattern of responses from an array of differently functionalized Au-NPF sensors can be used to distinguish analytes in the aqueous phase.