A bio-sniffer stick with FALDH (formaldehyde dehydrogenase) for convenient analysis of gaseous formaldehyde

A stick type biochemical gas sensor (bio-sniffer) with formaldehyde dehydrogenase (FALDH) was developed for convenient analysis of gaseous formaldehyde with high gas selectivity. The bio-sniffer for formaldehyde in the gas phase was constructed by immobilizing enzyme to a Pt electrode-coated hydrophilic PTFE membrane. The oxidation current of NADH produced by the FALDH enzymatic reactions was measured by amperometric analysis. The calibration ranges of the bio-sniffer for formaldehyde in the gas phase was from 40 to 3000 ppb, which encountered the maximum permissible concentration of formaldehyde vapor in the residential house (80 ppb) and formaldehyde detection limit for the human sense of smell (410 ppb). The FALDH immobilized sniffer indicated good gas selectivity based on the substrate specificity of FALDH as gas recognition material. As the results of the environmental application, the bio-sniffer was possible to measure the formaldehyde concentration from a building timber as an exterior frame material. The calculated concentration value by a regression analysis was consistent with those of a commercially available gas sensor and a gas detector tube for formaldehyde. (C) 2007 Elsevier B.V. All rights reserved.