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An automatic reagentless photometric procedure for the determination of ethanol in red wine is described. The procedure was
based on a falling drop system that was implemented by employing a flow injection analysis manifold. The detection system
comprised an infrared LED and a phototransistor. The experimental arrangement was designed to ensure that the wine drop grew
between these devices, thus causing a decrease in the intensity of the radiation beam coming from the LED. Since ethanol content
affected the size of the wine drop this feature was exploited to develop an analytical procedure for the photometric determination
of ethanol in red wine without using a chromogenic reagent. In an attempt to prove the usefulness of the proposed procedure,
a set of red wines were analysed. No significant difference between our results and those obtained with a reference method
was observed at the 95% confidence level. Other advantages of our method were a linear response ranging from 0.17 up to 5.14 mol L−1 (1.0 up to 30.0%) ethanol (R=0.999); a limit of detection of 0.05 mol L−1 (0.3%) ethanol; a relative standard deviation of 2.5% (n=10) using typical wine sample containing 2.14 mol L−1 (12.5%) ethanol; and a sampling rate of 50 determinations per hour. 相似文献