A field-portable gas analyzer with an array of six semiconductor sensors. Part 1: Quantitative determination of ethanol

A portable, battery-powered, flow-through analyzer incorporating six Taguchi semiconductor gas sensors was evaluated for use in food technology, where portability can be a major advantage for quality control and shelf-life testing. As an example, the headspace analysis of vapor above aqueous samples containing ethanol is reported. The portable, flow-through, multisensor gas analyzer has a simple design; is small (20 × 11 × 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 computer for real-time display of data during acquisition, making it practical for remote-site monitoring. The response to ethanol concentrations in the range 0.1-5.0% was recorded simultaneously for each sensor, and good stability, high sensitivity, selectivity, and reproducibility were demonstrated. The multisensor analyzer was able to discriminate between polar and nonpolar samples, such as ethanol and pure butane, and also between beer samples of similar ethanol content. Analysis results for ethanol in beer samples using the multisensor gas analyzer showed good agreement with gas chromatography results and with known concentrations. This multisensor gas analyzer has art advantage over a single sensor of producing a response pattern rather than a single signal. These patterns are shown to be useful for accurate quantitative analysis and also for identifying the nature of individual gas or vapor components in a particular sample. ©1998 John Wiley & Sons, Inc. Field Analyt Chem Technol 2: 135-143, 1998.