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W. Ritter, B. Lendl, S. Armenta Estrela, G. Quintas:
"Determination of Ethanol in Beverages by Vapour Phase Generation and MIR Photoacoustic Laser Spectroscopy";
in: "Informationstagung Mikroelektronik 08", herausgegeben von: Peter Balog, Bernhard Jakoby, Gottfried Magerl, Erwin Schoitsch, IEEE Austria; Österreichischer Verband für Mikroelektronik, Wien, 2008, S. 151 - 154.

A compact quantum cascade (QC) laser system with photoacoustic (PA) detection has been developed for the determination of ethanol in different kind of beverages. The analysis system was composed by a Fabry-Perot QC laser, a Helmholtz resonator cell and a single-channel assembly comprising a N2 carrier gas and a heated injection cell made of Pyrex.
The infrared absorption at 1080 cm-1 of the vapour phase generated in the injection cell was continuously recorded as a function of time. The obtained limit of detection was 0.095 % v/v with a precision of 0.8 % calculated from the relative standard deviation of 5 independent injections of a standard containing 9.6 % v/v ethanol. 27 commercially available beverages samples were analysed by the developed vapour phase QCL-PA spectroscopy procedure yielding results comparable with those obtained by an enzymatic reference method. Using the developed device a sample throughput of 21 h-1 and minimizes the waste generation can be achieved.