Development of a novel hand-held formaldehyde gas sensor for the rapid detection of sick building syndrome

• Published in: Sensors and actuators. B, Chemical Vol. 105; no. 2; pp. 495 - 501
• Main Authors: Kawamura, Koji, Kerman, Kagan, Fujihara, Mikiro, Nagatani, Naoki, Hashiba, Tomohiko, Tamiya, Eiichi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 28-03-2005
• Subjects: 4-Amino hydrazine-5-mercapto-1,2,4-triazole (AHMT); Formaldehyde; Hand-held gas sensor; Sick building syndrome; Sick building syndrome; Formaldehyde; Hand-held gas sensor; 4-Amino hydrazine-5-mercapto-1,2,4-triazole (AHMT)
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2004.07.010

The majority of conventional sensors for monitoring formaldehyde (HCHO) in air have several drawbacks, in terms of sensitivity, selectivity, and sampling time. In this report, a novel hand-held HCHO gas sensor for the sick building syndrome (SBS) prevention and control is developed with a significantly short sampling time.
A well-described reagent, 4-amino hydrazine-5-mercapto-1,2,4-triazole (AHMT) was utilized in the development of the novel gas sensor. AHMT of 100
μl and potassium hydroxide solution were dropped on a circular filter by using a specially developed hanging drop kit. When the filter was exposed to HCHO gas at the rate of 400
ml/min, AHMT reagent on the filter reacted with HCHO to produce a change in its color. The color change was recorded by measuring the intensity of reflected light using a photodiode, which was illuminated by an LED at 540
nm. The response was defined as % of the voltage drop.
The filter color intensity increased with sampling time in a concentration range of 0.04–1
ppm HCHO, and also the filter gave no response in the absence of HCHO. The limit-of-detection (LOD) of 0.04
ppm HCHO within a sampling time of 3
min was achieved. Thus, this method could be used to detect HCHO at the WHO standards (0.08
ppm) within 3
min.
Moreover, our device did not respond to other SBS causing reagents, such as other aldehydes and volatile organic compounds. In conclusion, we have developed a rapid, selective and simple HCHO gas sensor for SBS, which is also a suitable device for on-field operations.