A. Sharma et Nsm. Quantrill, MEASUREMENT OF ETHANOL USING FLUORESCENCE QUENCHING, Spectrochimica acta. Part A: Molecular spectroscopy, 50(6), 1994, pp. 1161-1177
A new assay procedure for the measurement of ethanol concentrations is
described which is based on fluorescence quenching of an indicator. T
he method makes use of the photo reaction between a fluorophore (thion
ine) and NADH. The latter is generated during an enzymic reaction betw
een ethanol and alcohol dehydrogenase (ADH) in the presence of nicotin
amide adenine dinucleotide (NAD+) cofactor. An empirical relation is u
sed to analyse the quenching, and a quenching constant of 27.2 (+/-2.8
) M-1 is obtained for the substrate induced quenching (SIQ) of thionin
e by ethanol. The reported method is suitable over a range of 0-40 mM
with a detection limit of 0.15 mM. A theoretical model for the overall
ethanol assay is developed, and its validity is shown by comparison w
ith the experimental results. Various applications of the reaction are
discussed, including its use to a fibre optic biosensor for ethanol.