On-line gaseous formaldehyde detection by a microfluidic analytical method based on simultaneous uptake and derivatization in a temperature controlled annular flow

Abstract

This paper is focused on the improvement of a microfluidic analytical method for the detection of low airborne formaldehyde concentrations, based on only two distinct steps permitting to reduce the response time and to improve the compactness of the device. First, gaseous formaldehyde is trapped into an acetylacetone solution at 65°C through an annular liquid/gas flow and reacts immediately to form 3,5-Diacetyl-1,4-dihydrolutidine which is then quantified by colorimetry using a liquid core waveguide (LCW). To obtain an annular flow, 3 different hydrophilic silica capillaries of 320, 450 and 530µm ID were tested and the corresponding phase diagrams were obtained in the ranges of liquid and gas flows of 5-35µLmin and 5-35mLmin respectively. Finally, the analytical performances were determined using the lowest flow values of 5µLmin and 5NmLmin, ensuring an annular flow and increasing the microdevice autonomy. If the uptake yield of gaseous formaldehyde into the solution was close to 100%, only the 530µm ID capillary permits to obtain a reaction time long enough for a full conversion of formaldehyde into 3,5-Diacetyl-1,4-dihydrolutidine. With a LCW pathlength of 5cm, the microdevice response was perfectly linear in the range 0-154µgm with a detection limit of 1.8µgm.

Impact of material emissions and sorption of volatile organic compounds on indoor air quality in a low energy building: Field measurements and modeling

“…Similar conclusions were found for formaldehyde measurements with a dedicated analyzer and then modeled. Monoterpenes are overestimated by a factor of 3.5 using the PTR‐ToF‐MS emission measurements, whereas the GC emission rate measurements without the camphene (coeluted with 124 TMB) satisfactorily reproduce the indoor profiles.…”

Near Real-Time Monitoring of Formaldehyde in a Low-Energy School Building

“…The objectives of this study are two-fold: firstly, to provide experimental data on the temporal variations of aldehydes concentrations in a Low-Energy building, and secondly, to test, under real conditions, a new formaldehyde analyzer which has already been validated by previous laboratory studies [17,18]. Therefore, this work reports formaldehyde and aldehydes measurements in indoor air for two weeks during the MERMAID intensive field campaign performed in a junior high school recently built according to the French thermal regulation of 2005.…”

“…The analytical method recently developed in our laboratory was already detailed in our previous studies [17,18]. As shown in Figure 1, this analytical method is also based on three highly coupled steps: (1) the uptake of gaseous formaldehyde into an aqueous acetylacetone solution at room temperature;…”

“…Air is sampled at 20 mL min −1 by a mass flow controller (IQ+Flow, Bronkhorst) combined to a mini air pump (270 EC, Schwarzer) to maintain a stable gas flow injected coaxially into the capillary of 150 cm long and 530 µm ID. At the same time, the aqueous acetylacetone liquid solution prepared according to the same procedure mentioned above is continuously injected at 17 µL min −1 by a micro peristaltic pump through a specific Tee into the same capillary [17,18]. The coinjection of both the gas mixture and the aqueous acetylacetone solution into the capillary (see Figure S3) permits a diphasic flow to be obtained.…”

“…Although the pollution levels in conventional buildings have been largely studied, in particular, in France, with the large-scale investigations by the French indoor air quality observatory (OQAI) [2], not much is known about the indoor air quality of low-energy buildings, be it private dwellings [3] or [26] Acetyl acetone + fluorescence (1st generation of formaldehyde analyser) 0.5 (S/N = 3) 6-10 min None identified 1100 6 8 2 [30] Acetyl acetone + Colorimetric microfluidic device 0.7 (S/N = 3) 1-2 min None identified 35 9 8 [17,18] Acetyl acetone + Fluorimetric microfluidic device 1.2 (S/N = 3) 2 s None identified 20 4 This work N/A: Information not available; 1 DNPH: 2,4-dinitrophenylhydrazine and HPLC/UV-vis: High-Performance Liquid Chromatography coupled to UV-visible detection; 2 It corresponds only to the instrument weight and does not refer to the total weight of the operating system, i.e., it does not include any liquid reagents reservoir or gas cylinder; 3 GC-MS: Gas Chromatography coupled to Mass Spectrometer; 4 FTIR: Fourier-transform infrared spectroscopy; 5 PTR/MS: Proton-transfer-reaction mass spectrometry 6 Two reagents are needed; 7 Three reagents are involved; 8 The deuterium lamp DH-2000 (Ocean Optics) weighs 5.5 kg whereas the microfluidic device is around 3.5 kg including its electronic part.…”