Abstract
A new device (Passive Emission Colorimetric Sensor: PECS) has been developed to easily and precisely measure the emission rates of formaldehyde from various surfaces in residential houses. PECS is a very small device (external diameter: 23mm, thickness: 3.2mm). PECS consists of a polyethylene terephthalate (PET) body and a test paper, which turns red by enzyme reaction in the presence of formaldehyde. At the beginning of measurement, 1 drop of pure water is put into the PECS, the PECS is placed on each of the indoor materials, and 30 minutes later the coloration can be measured by visual observation or absorption photometry.
The response to the color change of PECS in the measurement of reflectance was correlated with the concentration of the solution between 0.4 and 20μg/mL (R2>0.99). In measuring the emission rates from plywood with any order of emission rates using PECS and the desiccator method, both results were nonlinearly correlated (blue LED: y = 0.225x0.444,R2 = 0.995, green LED: y = 0.233x0.529, R2 = 0.992). The precision (N = 7) of the measurement was 4.3% ~ 13 %. The lower limit of quantification (LOQ) of the emission rates measured by PECS were equivalent to 0.06 mg/L measured by the desiccator method. This LOQ is much lower than the emission rates of normal plywood in class F ****(<0.3mg/L).
