[Talanta] On-line gaseous formaldehyde detection by a microfluidic analytical method based on simult
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 530 µm ID were tested and the corresponding phase diagrams were obtained in the ranges of liquid and gas flows of 5–35 µL min−1 and 5–35 mL min−1 respectively.
Finally, the analytical performances were determined using the lowest flow values of 5 µL min−1 and 5 NmL min−1, 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 530 µm 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 5 cm, the microdevice response was perfectly linear in the range 0–154 µg m−3 with a detection limit of 1.8 µg m−3.
Maud Guglielminoa, b, Pierre Bernhardta, c, Claire Trocqueta, c, Christophe A. Serrab, Stéphane Le Calvéa, c, , a Institut de Chimie et Procédé pour l’Energie, l’Environnement et la Santé (ICPEES, UMR 7515 CNRS/UdS), Group of Atmospheric Physical Chemistry, 25 rue Becquerel, 67087 Strasbourg Cedex 02, France b Université de Strasbourg, CNRS, ICS UPR 22, F-67000 Strasbourg, France c In’Air Solutions, 1 rue Blessig, 67000 Strasbourg, France Received 26 January 2017, Revised 9 May 2017, Accepted 12 May 2017, Available online 13 May 2017