UiO-66/Multiwalled Carbon Nanotube Nanocomposite-Coated Quartz Crystal Microbalance Gas Sensor for Discriminating Amine and Formaldehyde.

Amine gases and formaldehyde (HCHO) have been used as typical indicators to monitor the quality of marine fish products. However, current detection methods are time-consuming and complicated to preprocess and have limitations such as high technicality requirements. Therefore, developing a sensor capable of simultaneously detecting multiple amine gases and HCHO with high performance in a simple way remains a significant challenge. In this paper, trimethylamine (TMA), dimethylamine (DMA), ammonia gas (NH₃), and HCHO were tested by a quartz crystal microbalance (QCM) gas sensor modified with a UiO-66/multi-walled carbon nanotube (MWCNT) nanocomposite. The sensor was operated at room temperature (25 °C) and fixed humidity (35% RH), and the results showed that the limits of detection of the QCM gas sensor for TMA, DMA, NH₃, and HCHO were 0.32, 0.52, 1.02, and 2.4 μmoL L^–1, respectively. At the same time, our sensor could be reused more than ten times without degradation of sensor signals and showed high stability even after a long storage period of up to 2 months. The adsorption mechanism of the UiO-66/MWCNT nanocomposite-based QCM gas sensor toward the target gases was simulated. Ultimately, salmon meat was examined using the sensor that had been prepared, and the detection outcomes were contrasted with the findings from the Kjeldahl nitrogen determination. The results indicated that refrigerated salmon began emitting target gases on the second day and gradually increased thereafter. By the fifth day, the concentration of the target gases reached the point of complete spoilage. Our platform may be a promising platform for basic research and versatile practical applications in food quality assessments. [ABSTRACT FROM AUTHOR]