A NOVEL ENZYME BIOSENSOR SPECIFIC FOR FORMALDEHYDE BASED ON PH-SENSITIVE FIELD-EFFECT TRANSISTORS

An enzyme biosensor specific for formaldehyde has been developed using pH-sensitive field effect transistors (FET) as a transducer and alcoh ol oxidase (AOX) from Hansenula polymorpha as a sensitive element. The steady-state response time of the developed biosensor was 10-60 s. Th e linear dynamic range (in semi-logarithmic scale) of the sensor outpu t signal corresponded to 10-300 mmol dm(-3) formaldehyde concentration . The operational stability of the biosensor was not less than 7 h and the relative standard deviation approximately 1-3%. When stored at +4 degrees C, the response was stable for more than 30 days. The biosens or demonstrated high specificity to formaldehyde with no potentiometri c response to primary alcohols. The influence of buffer concentration and enzyme concentration in the biomembrane on the sensor signal was i nvestigated. The specific biosensor could also be successfully used fo r highly selective, quantitative estimation of mercury ion in an aqueo us solution.