Accurate and continuous monitoring of indoor air quality is crucial to understand and prevent airborne diseases, since humans spend most of their routine time indoors. Aldehydes are of particular interest as they are irritants and usually present in indoor air at concentrations from 2 to 10 times higher than in outdoor air. Formaldehyde, the most abundant one, is classified as carcinogenic category 1B under European Regulation (EC) No 1272/2008. In indoor air, aldehydes mainly originate from construction materials such as plywood, insulating materials and paints. Some aldehydes have a pungent and fruity odour at high concentrations but may be undetected at low concentration. To be able to implement preventive measures, there is a need for continuous, fast, accurate and robust techniques for quantification of aldehydes in indoor air.
In this work, two different systems which have been developed for monitoring of formaldehyde and other aldehydes are presented: a portable microdevice based on the derivatization of formaldehyde for continuous fluorometric detection, and an Automatic Gas 2D-chromatograph equipped with a thermodesorption unit and flame ionization detector (auto-TD-GC-FID). These techniques were compared under laboratory-controlled measurements. The portable microdevice specifically quantifies formaldehyde down to ppb levels. It is compact and uses a specific aqueous reagent to convert formaldehyde into a fluorescent product, 100 mL enabling a continuous monitoring for 4 days. The auto-TD-GC-FID is an automatic gas chromatograph permitting formaldehyde and acetaldehyde quantification from ppb to ppm levels. It runs continuously with successive 15-min cycles. This instrument only requires a power supply and gas generators or gas cylinders of hydrogen, air, and nitrogen. Our experimental results demonstrate that both analytical devices quantify formaldehyde accurately.