Formaldehyde passive sampler using an optical chemical sensor: how to limit the humidity interference

Area of Science:

• Environmental Science
• Analytical Chemistry
• Sensor Technology

Background:

• Formaldehyde is a common indoor air pollutant.
• Conventional passive samplers require laboratory analysis, limiting real-time monitoring.
• High humidity can interfere with the accuracy of air sampling devices.

Purpose of the Study:

• To evaluate the performance of a novel formaldehyde diffusive sampler under high humidity conditions.
• To compare humidity interference across five different prototypes of the radial diffusion sampler.
• To identify a formaldehyde diffusive sampler design least affected by humidity for on-site measurements.

Main Methods:

• Testing five formaldehyde diffusive sampler prototypes with optical chemical sensors in controlled atmospheres.
• Characterizing water vapor trapping efficiency of the chemical sensor with and without reactants (Fluoral-P and formaldehyde).
• Analyzing humidity interference differences among the prototypes.

Main Results:

• Prototype LDE1.4 demonstrated the least humidity interference up to 80% relative humidity at 20°C.
• This prototype features a small diffusion slot, reduced internal volume, and an upward-shifted sensor.
• Humidity significantly impacted formaldehyde measurements in other prototypes.

Conclusions:

• The LDE1.4 formaldehyde diffusive sampler offers reliable on-site direct reading capabilities.
• This innovative sampler is a promising alternative to conventional DNPH-based passive samplers.
• The design effectively mitigates humidity interference in formaldehyde detection.