Thin Film Composite Conductive Polymers Chemiresistive Sensor and Sample Holder for Methanol Detection in Adulterated Beverages

Abstract

An inexpensive methanol sensor lid fabricated from a composite conductive polymer comprised of cellulose nanocrystals, carbon nanotubes and polyanilines (PANI@CNC/CNT) has been demonstrated. The sample holder composed of an inexpensive tube with Kanthal resistive heating for preferential methanol headspace sampling. The PANI@CNC/CNT nanoporous aerogel film has inherent ultra-high surface area, with the CNT/PANI free valence electrons affording a high electrical conductive material. The PANI@CNC/CNT methanol sensor performance was tested for its response to methanol, ethanol standards and methanol/ethanol mixtures. The sensor was 46 times more sensitive and selective to methanol compared to ethanol, and afforded a linear response in the 0-7% methanol concentration range, deviating from linearity above 10%. The sensor was also used to test methanol standards spiked in wine, yielding a linear (R2 = 0.9842) resistance change in response with methanol concentrations in the range, 0-7%. The sensor precision for triplicate standards for different concentrations (0.5-5.0%) averaged ~4.5%, indicating overall reliability of the device. With sample heating and detection time fixed at 10 mins, the sensor demonstrated optimal performance with a limit of detection of 0.30% for methanol. The sensor was tested for over 24 runs over a one-month period without significant loss in performance due to degradation. multiple uses without degradation in performance. The PANI@CNC/CNT has been found effective for as a dosimetric sensor for use in indoor air quality monitoring and beverage adulteration analysis.