(sensors based on injection of the recognition element) Biosensor, which is an amperometric biosensor. The method was simple, fast, accurate,
specific and cost-effective. The recognition element solution used was stable at least for 24 h in room temperature, and at least one month
when lyophilised. The optimal potential versus the silver wire electrode, the optimal pH of the buffer and the optimal temperature of the water
bath was determined to be +950mV, 8.1 and 308 K, respectively. The optimal concentrations of alcohol dehydrogenase, BSA and NAD+ were
determined to be 200 U/ml, 20 mg/ml and 15 mM, respectively. The total analysis time was between 50 s and 4 min per analysis, depending
on the concentration range. The linear range was 0–12.5 mM. The detection limit was less than 0.1 mM. The repeatability (%R.S.D.) was
3–5% (n = 10). The reproducibility was 5–8% (n = 5). Methanol gave no signal at all, but higher alcohols, such as propanol, pentanol and
hexanol, gave significant signals, decreasing with increasing length of the carbon chain. The price for one measurement was calculated to
be 0.052 euro. The results from measurements with the biosensor were compared to those from an established analysis kit for ethanol. The
results correlated well (R2 = 0.9874). The concentration of ethanol in different alcoholic beverages was investigated and correlated well with
the concentrations given by the manufacturers.
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