An enzymatic-fluorimetric method for monitoring of ethanol in ambient air

A method is described for the continuous monitoring of ethanol in ambient a ir. The system consists of a scrubber coil for enrichment of the analyte fr om air in an aqueous solution and a directly connected, fluorescence detect or. Because of using a reagent solution containing alcohol dehydrogenase (A DH) and nicotinamide adenine dinucleotide (NAD(+)) for absorption, ethanol can react directly with ADH and NAD(+) during air sampling, producing NADH, which can be measured by fluorescence detection. The influence of reagent concentrations, gas flow rate and scrubber solution flow rate on the perfor mance of the. instrument was tested. Possible ozone interferences can be av oided by placing a KI coated filter in front of the scrubber inlet. The res ponse time of the,system was found to be 2.3 min and the detection limit ab out 1 ppb(V). The applicability of the developed method was demonstrated du ring a field campaign in Brazil.