Prof. Nicole JAFFREZIC-RENAULT
Franche-Comte University
Dr Nicole Jaffrezic-Renault received her engineering degree from Chimie ParisTech, Paris, in 1971 and the Doctorat d’Etat és Sciences Physiques from the University of Paris-Saclay in 1976. She is Emeritus Director of Research at CNRS, past president of the chemical micro sensor club (CMC2), president of the Analytical Division of the French Chemical Society. She was decorated as Knight of the National Order of Legion of Honor and Officer of the National Order of Merit. Her research activities in the Institute ISA University of Lyon and now at the Institute UTINAM University of Franche-Comte, include conception and design of (bio)chemical sensors and their integration in microsystems. She coordinates several European and national projects for the development of microsystems for biomedical and environmental monitoring and for food safety. She published more than 655 papers with more than 15300 citations (H index: 65).
VOC biosniffers for food quality control and breath control
Nicole JAFFREZIC-RENAULT
UTINAM Institute, Franche-Comte University, Besancon, France
nicole.jaffrezic-renault@univ-fcomte.fr
Volatile organic compounds (VOCs) are chemicals with a relatively high vapor pressure at room temperature and atmospheric pressure so they vaporize readily. In the environment, Sources of VOC emission are widespread and can be of natural origin or through human activities. VOC can be used in breath to indicate health conditions and in packaging for controlling food quality. The techniques for quantifying VOC are GC-MS, PTR-MS, etc; these devices are bulky, expensive, and time-consuming. Semiconducting metal oxide-based gas sensors are cheap, miniaturized, and very sensitive; their main drawbacks are their high working temperature and rather bad specificity. Taking advantage of the enzyme selectivity, enzyme-based sensors were used as ‘‘bio-sniffer’’ for detecting different types of VOC.
Detection of ethanol in food
Analysing the headspace above the liquid sample, instead of the liquid sample itself, offers the advantage that possible non-volatile interfering substances in the liquid sample (e.g. ascorbic acid) cannot impair the measurement. The relation between the gas phase concentration at room temperature and the liquid concentration was calculated from Henry’s law constants (kH) compiled by Sanders [1]. Fruit juice can contain small amounts of ethanol due to the fermentation of the fruits during storage before juice processing; the maximum permitted level of ethanol is 65 mM. An electrochemical detection of ethanol was carried out, using a 3-electrode configuration with a Pt gas diffusion electrode as the working electrode [2]. The amperometric detection of hydrogen peroxide, produced by the enzymatic reaction of the alcohol oxidase, allowed the detection of ethanol in the gas phase. The response time was 1 min and the detection limit was 10 µM. The concentration of ethanol, in different apple juices, was determined, and overestimated, compared to the HPLC result, due to the low sensitivity to methanol of the AOx. A simple conductometric microsensor, based on interdigitated electrodes and alcohol dehydrogenase immobilized in a chitosan film on top of the sensor, will be presented, for the detection of ethanol in the headspace of commercial wine [3].
Detection of ethanol in breath
An acetaldehyde “biosniffer”, based on the reverse reaction of alcohol dehydrogenase, was composed of an UV-LED as an excitation light source, a photomultiplier tube as a fluorescence detector and an optical fiber. This biosniffer shows a response time of less than 2 min and a dynamic range of 0.02 – 10 ppm, and was applied to measure the concentration of acetaldehyde in exhaled breath from healthy subjects after ingestion of alcohol.
References
[1] R. Sander, Compilation of Henry’s law constants for inorganic and organic species of potential importance in environmental chemistry, version 3, 1999. www.henrys-law.org. Accessed 09 Mar 2021.
[2] M. Hämmerle, K. Hilgert, M.A. Horn, R. Moos. Sensors and Actuators B 2011, 158, 313-318
[3] A. Madaci, N. Jaffrezic-Renault et al. J Mater Sci: Mater Electron 2021, 32, 17752–17763
[4] K. Iitani, P.J. Chien, T. Suzuki, K. Toma, T. Arakawa, Y. Iwasaki, K. Mitsubayshi. ACS Sensors 2018, 3, 425-431.
