A FIELD-PORTABLE GAS ANALYZER WITH AN ARRAY OF 6 SEMICONDUCTOR SENSORS - PART 1 - QUANTITATIVE-DETERMINATION OF ETHANOL

A portable, battery-powered, flow-through analyzer incorporating six T aguchi semiconductor gas sensors was evaluated for use in food technol ogy, where portability can be a major advantage for quality control an d shelf-life testing. As an example, the headspace analysis of vapor a bove aqueous samples containing ethanol is reported. The portable, flo w-through, multisensor gas analyzer has a simple design; is small (20 x 11 x 6 cm), lightweight (985 g), and battery powered (6.0-V battery pack), requires low power (6.6 W), and is connected to a notebook comp uter for real-time display of data during acquisition, making it pract ical for remote-site monitoring. The response to ethanol concentration s in the range 0.1-5.0% was recorded simultaneously for each sensor, a nd good stability, high sensitivity, selectivity, and reproducibility were demonstrated. The multisensor analyzer was able to discriminate b etween polar and nonpolar samples, such as ethanol and pure butane, an d also between beer samples of similar ethanol content. Analysis resul ts for ethanol in beer samples using the multisensor gas analyzer show ed good agreement with gas chromatography results and with known conce ntrations. This multisensor gas analyzer has an advantage over a singl e sensor of producing a response pattern rather than a single signal. These patterns are shown to be useful for accurate quantitative analys is and also for identifying the nature of individual gas or vapor comp onents in a particular sample. (C) 1998 John Wiley & Sons, Inc.