On-Line Gaseous Formaldehyde Detection Based on a Closed-Microfluidic-Circuit Analysis

Abstract

This paper describes a compact microfluidic analytical device in a closed-circuit developed for the detection of low airborne formaldehyde levels. The detection is based on the passive trapping of gaseous formaldehyde through a microporous tube into the acetylacetone solution, the derivative reaction of formaldehyde with acetylacetone to form 3,5-Diacetyl-1,4-dihydrolutidine (DDL) and the detection of DDL by fluorescence. The recirculation mode of the analytical device means that the concentration measurement is carried out by quantification of the signal increase in the liquid mixture over time, the instantaneous signal increase rate being proportional to the surrounding gaseous formaldehyde concentration. The response of this novel microdevice is found to be linear in the range 0–278 µg m−3. The reagent volume needed is flexible and depends on the desired analytical resolution time and the concentration of gaseous formaldehyde in the environment. Indeed, if either the gaseous concentration of formaldehyde is high or the reagent volume is low, the fluorescence signal of this recirculating liquid solution will increase very rapidly. Consequently, the sensitivity simultaneously depends on both the reagent volume and the temporal resolution. Considering a reagent volume of 6 mL, the hourly and daily detection limits are 2 and 0.08 µg m−3, respectively, while the reagent autonomy is more than 4 days the airborne formaldehyde concentration does not exceed 50 µg m−3 as it is usually the case in domestic or public indoor environments.

Microfluidic integrated gas sensors for smart analyte detection: a comprehensive review

“…The excited electrons then undergo energy loss and generate electromagnetic radiation by which they can be identified. Becker et al developed a microfluidic FL gas detector (20 cm × 25 cm × 15 cm) to detect formaldehyde with a detection limit of 0.08 μg m −3 ( Becker et al, 2020 ). In this device, a porous interface is used to trap formaldehyde in the acetylacetone solution, where the Hantzsch reaction transforms the trapped formaldehyde into a fluorescent molecule 3,5-Diacetyl-1,4-dihydrolutidine (DDL).…”

Development of a Portable and Modular Gas Generator: Application to Formaldehyde Analysis

“…Once the derivatization fully occurred, DDL is detected by fluorescence, the excitation occurring at 415 nm and the fluorescence being collected on a photomultiplier (Hamamatsu, Massy, France) at 530 ± 40 nm [14,39,40]. Then, the fluorescence signal is amplified with a photomultiplier and averaged over two seconds.…”

“…To overcome this drawback for gaseous formaldehyde quantification, the current trend in this analytical field is to develop real-time measurement tools such as sensors [30][31][32][33][34][35], analysers [36][37][38] or even microanalyzers [14,[39][40][41][42]. Chemical sensors are based on various gas detection mechanisms [43], namely resistive/chemoresistive, electrochemical, metaloxide-semiconductor field effect transistors (MOSFET), optical (surface plastic resonance (SPR)) and surface acoustic.…”

Adsorption of gaseous formaldehyde on Y zeolites and on metal-organic frameworks

“…Its ubiquitous nature, its occurrence in indoor environments and its impact on human health make formaldehyde of great societal and scientific interest [8,18,[25][26][27][28]. Scientists are continuing to develop measurement methods for this pollutant and in particular real-time instruments such as analysers [29][30][31][32][33][34][35][36] and sensors [37][38][39][40][41][42] for monitoring indoor air. In addition, low cost indoor air quality measurement devices are now available for individuals willing to improve the quality of the air they breathe [43,44].…”

“…Adsorption techniques are widely used for air pollution control [45][46][47] and sampling of pollutants before desorption and analysis by off-line or on-line methods [29][30][31]33,34,48,49]. However, the efficiency of common adsorbents towards the formaldehyde molecule is limited due to its high polarity and small size.…”