A Sensitive Micro Conductometric Ethanol Sensor Based on an Alcohol Dehydrogenase-Gold Nanoparticle Chitosan Composite

In this paper, a microconductometric sensor has been designed, based on a chitosan composite including alcohol dehydrogenase—and its cofactor—and gold nanoparticles, and was calibrated by differential measurements in the headspace of aqueous solutions of ethanol. The role of gold nanoparticles (GNPs) was crucial in improving the analytical performance of the ethanol sensor in terms of response time, sensitivity, selectivity, and reproducibility. The response time was reduced to 10 s, compared to 21 s without GNPs. The sensitivity was 416 µS/cm (v/v%)−1 which is 11.3 times higher than without GNPs. The selectivity factor versus methanol was 8.3, three times higher than without GNPs. The relative standard deviation (RSD) obtained with the same sensor was 2%, whereas it was found to be 12% without GNPs. When the air from the operator’s mouth was analyzed just after rinsing with an antiseptic mouthwash, the ethanol content was very high (3.5 v/v%). The background level was reached only after rinsing with water

A novel conductometric sensor for acetone detection prepared through electro-polymerization of pyrrole-tailed ionic liquid

International audiencePoly(ionic liquid)s (PILs), otherwise known as polymerized ionic liquids, are a subclass of polyelectrolytes that comprises an ionic liquid (IL) species as a monomer repeating unit, connected through a polymeric backbone to form a macromolecular architecture. Since their discovery, these polymers have attracted wide attention due to their various and tunable properties. These properties include their ionic conductivity, thermal and chemical stability, and low cost. In this work, a conductometric transducer is proposed for the detection of acetone vapor. This acetone microsensor is prepared by two steps electro-polymerization. First, a thin film of polypyrrole was electrochemically deposed on interdigitated gold electrodes using cyclic voltammetry (CV) electro-polymerization followed by the electropolymerization of our synthesized pyrrole-functionalized Ionic Liquid (PyC8MImBF4). The interdigitated electrodes were fabricated by silicon technology. The polypyrrole PILs electrodeposited onto the interdigitated electrodes were widely characterized using EDX; SEM; XPS; FTIR, profilometry, CV, and Contact angle measurement. The analytical performance of the acetone microsensor was determined in gaseous ethanol, acetone, toluene, chloroform, and methanol samples, collected from the headspace above aqueous solutions of known concentration. Ethanol, acetone, toluene, chloroform, and methanol gas-sensing responses of the films were measured at room temperature, through differential conductometric measurements conducted at 10 kHz. The response time (tRes) of the sensor varies from 6 to 13 s from lower concentrations to higher concentrations. The detection limit is 2.83 v/v % in the gas phase, corresponding to 0.68 M in the liquid phase. The relative standard deviation for the same sensor is 6% for lower concentrations and 2% for higher concentrations. The acetone sensor presents 24 times lower sensitivity for ethanol, 57 times lower sensitivity for toluene, 33 times lower sensitivity for chloroform, and 10 times lower sensitivity for methanol. A detection of acetone in the headspace of a nail varnish remover sample leads to the alcohol content being in good agreement with the value given by the producer

Conductometric Sensor Based on Electropolymerized Pyrrole-Tailed Ionic Liquids for Acetone Detection

International audienceIn the chemical industry and research institutes, acetone serves routinely as a solvent, a reactant, and an extractant. However, due to its high volatility and toxicity, monitoring its vapor concentration is of great necessity for health and industrial safety. Besides this, simple and easy-to-use portable sensors are still lacking. In this work, a conductometric transducer was developed for the detection of acetone vapor. For this, interdigitated electrodes were functionalized by electropolymerization of a series of N-(1-methyl-3-octylimidazolium)pyrrole [PyC8MIm]X monomers that contain different counteranions X–, namely, hexafluorophosphate (PF6–), tetrafluoroborate (BF4–), and bis(trifluoromethylsulfonyl)imide (TFSI–). The functionalized interdigitated electrodes were widely characterized. The analytical performances of the microsensors were determined in the presence of gaseous acetone, chloroform, ethanol, methanol, and toluene, collected from the headspace of the above aqueous solutions of known concentrations. The gas-sensing responses of the films were measured at room temperature through differential conductometric measurements conducted at 10 kHz. Among the different sensors, the one bearing BF4– anions presented the best analytical performances and was able to selectively detect acetone vapors. The sensor’s response time (tres) varied from 6 to 13 s from lower to higher concentrations. The detection limit was 0.76 v/v % (7600 ppm) in the gas phase. The relative standard deviation was 6% for lower concentrations and 2% for higher concentrations. The acetone sensor presented 2 times lower sensitivity for ethanol and 4 times lower sensitivity for methanol. Detection of acetone in the headspace of a nail varnish remover sample led to an acetone content that was in compliance with the value given by the producer

A microconductometric ethanol sensor prepared through encapsulation of alcohol dehydrogenase in chitosan: application to the determination of alcoholic content in headspace above beverages

International audienceA conductometric transducer is proposed for the first time for the detection of ethanol vapor. This ethanol microsensor is prepared by encapsulation of alcohol dehydrogenase (ADH) in chitosan. Interdigitated electrodes fabricated by silicon technology were used. The electrodeposition of chitosan allows the addressing of the chitosan film on the microconductometric devices and to encapsulate ADH and nicotinamide adenine dinucleotide (NAD?), which was monitored by FTIR. The analytical performance of the ethanol microsensor was determined in gaseous methanol, ethanol, and acetone samples, collected from the headspace above aqueous solutions of known concentration. The response time (tRec) of the sensor varies from 7 to 21 s from lower concentrations to higher concentrations. The detection limit is 0.12v/v % in the gas phase, correspondingto 0.22 M in the liquid phase. The relative standard deviation for the same sensor is from 12% for lower concentrations to 2% for higher concentrations. The ethanol sensor presents 2.6 times lower sensitivity for methanol and 28.3 times lower sensitivity for acetone. A detection of ethanol in the headspace of a red wine sample lead to an alcohol content in good agreement with the value given by the producer