A Novel Conductometric Methanol Sensor Based on Green-Synthesized Fe3O4-Nanoparticles

Methanol (MeOH) is widely used in industry and is highly toxic when ingested. In this work, a new micro-conductometric transducer is functionalized with magnetic Fe3O4 nanoparticles capped with Artemisia Herba Alba (AHA) extract. The resulting AHA-Fe3O4 nanoparticles, crystallized in the cubic spinel phase, exhibit an average crystallite size of 6 nm. These nanoparticles were homogeneously dispersed within an electrodeposited chitosan film on interdigitated electrodes for conductometric measurements. The gas-sensing behavior of the films was evaluated at room temperature toward methanol, ethanol, and acetone vapors. For methanol, the sensor shows response times (tRes) ranging from 9 to 12 s depending on the analyte concentration, with a detection limit of 600 ppm in the gas phase. The methanol sensor presents a sensitivity 30 times lower for acetone and 3.7 times lower for ethanol. The sensor exhibited stable detection sensitivity over two months, under intermittent storage at 4 °C. Methanol was detected in the headspace of commercial product samples, in good agreement with the producer’s value.