Ethanol is determined by a sensor system using purified,
immobilized mernbrane-bound alcohol dehydrogenase frorn Gluconobacter suboxydans, attached to a
platinum disk electrode (3 mm diameter), and covered with a dialysis membrane.
Hexacyanoferrate (III) is used as the redox acceptor. To
correct for the influence of interfering substances, this alcohol sensor is
compensated by a control electrode which has no immobilized enzyme. The
potential of these platinum electrodes was set at + 350 mV vs. Ag/AgCl.
Linearity was observed in the range 0.1–5 mM ethanol, the response time was
less than 5 min, the maximum sensitivity was obtained at 45°C and the optimum
pH was in the range 4.5–5.5.
The sensitivity decreased to 80% of the initial value after
1 month at 30°C. When the alcohol sensor system was applied to the
determination of ethanol in alcoholic beverages, a good correlation was
obtained between the results and those obtained by gas chromatography.
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