Development of a portable monitor for a formaldehyde in the workplace environment

A portable formaldehyde gas monitor was developed and applied to measurements of the workplace environment using a sensitive and selective tablet for formaldehyde. It is based on a color change of the tablet by a reaction with formaldehyde. A tablet impregnated with a processing solution containing KD-XA01, phosphate buffer solution in methanol was found to be a highly sensitive and selective for the detection of formaldehyde. When a sample including formaldehyde was exposed to the tablet, the surface color of the tablet changed from white to yellow. The degree of the color change was proportional to the concentration of formaldehyde at a constant sampling time and flow rate, which was recorded by measuring the relative intensity of reflecting light at 400 nm. The tablet was used to detect 0.3 ppm of formaldehyde, which was set by ACGIH, with a sampling time of 3 min and a flow rate of 250 ml/min. Reproducibility tests showed that the relative standard deviation of the response (n = 10) was 2.1% for 0.3 ppm of formaldehyde. This monitoring method is simple, specific, and capable of unattended operation, and is recommended for the workplace environment.