Conductometric formaldehyde sensitive biosensor with specifically adapted analytical characteristics

A conductometric enzyme biosensor for determination of formaldehyde in aque ous solutions has been developed using interdigitated thin-film planar elec trodes and immobilised alcohol oxidase from Hansenula polymorpha. The biose nsor steady-state response was reached after about I min. Its dynamic range can vary from 0.05 to 500 mM formaldehyde and depends on the time of enzym atic membrane cross-linking by glutaraldehyde and on the buffer concentrati on used. The biosensor developed was not completely specific and selective. It demonstrated no response to primary alcohols and other substrates alone . Unfortunately, the response of this biosensor in a mixture of formaldehyd e and methanol was decreased in comparison to the one observed for pure for maldehyde, even if no response was obtained with the interfering specie alo ne. The operational stability was not <20 h and the relative standard devia tion appeared to be about 3%. Moreover, the storage stability was more than 1 month. (C) 2001 Elsevier Science B.V. All rights reserved.