A new device for formaldehyde and total aldehydes real-time monitoring.

A new sensitive technique for the quantification of formaldehyde (HCHO) and total aldehydes has been developed in order to monitor these compounds, which are known to be involved in air quality issues and to have health impacts. Our approach is based on a colorimetric method where aldehydes are initially stripped from the air into a scrubbing solution by means of a turning coil sampler tube and then derivatised with 3-methylbenzothiazolinone-2-hydrazone in acid media (pH = -0.5). Hence, colourless aldehydes are transformed into blue dyes that are detected by UV-visible spectroscopy at 630 nm. Liquid core waveguide LCW Teflon® AF-2400 tube was used as innovative optical cells providing a HCHO detection limit of 4 pptv for 100 cm optical path with a time resolution of 15 min. This instrument showed good correlation with commonly used techniques for aldehydes analysis such as DNPH derivatisation chromatographic techniques with off-line and on-line samplers, and DOAS techniques (with deviation below 6%) for both indoor and outdoor conditions. This instrument is associated with simplicity and low cost, which is a prerequisite for indoor monitoring.

Multi-tool formaldehyde measurement in simulated and real atmospheres for indoor air survey and concentration change monitoring.

Formaldehyde is of particular health concern since it is carcinogenic for human and ubiquitous in indoor air where people spend most of their time. Therefore, it is important to have suitable methods and techniques to measure its content in indoor air. In the present work, four different techniques have been tested in the INERIS exposure chamber and in indoor environments in comparison to a standard active method: passive sampling method based on the reaction of 2,4-dinitrophenylhydrazine with formaldehyde, two on-line continuous monitoring systems based on fluorescence and UV measurements and a portable commercialised analyser based on electrochemical titration. Two formaldehyde concentrations, about 10 and 25 µg m(-3) were generated in an exposure chamber under controlled conditions of temperature, relative humidity, and wind speed to simulate real conditions and assess potential influence on passive sampling and continuous systems response. Influence of sampling periods on passive sampling has also been evaluated. The real atmosphere experiments have been performed in four different indoor environments: an office, a furniture shop, a shopping mall, and residential dwellings in which several potential formaldehyde sources linked to household activities have been tested. The analytical and sampling problems associated with each measurement method have been identified and discussed. An overall agreement between each technique has been observed and continuous analyzers allowed for formaldehyde concentrations change monitoring and secondary formation of that pollutant observation.