Utilizing Colorimetric Gas Sensors as a Selective Detector for Gas Chromatography

Colorimetric gas sensors show promise as selective detectors for gas chromatography (GC), but their application has been limited by the irreversibility of their responses. This study presents the successful hyphenation of colorimetric gas sensors with GC, overcoming this limitation through a novel approach that refreshes the sensor's reaction area with controlled movement, enabling the generation of reversible GC peaks. The sensors, based on acid-base indicators, such as chlorophenol red and bromocresol green, were integrated with a capillary GC column and evaluated for amine detection. Performance testing revealed satisfactory sensitivity, linearity, and reproducibility, with the colorimetric sensors demonstrating superior selectivity for amines compared to flame ionization detectors (FID). Moreover, a dual-sensor array, combined with a pattern recognition algorithm, enabled effective discrimination between various amine compounds. This work establishes a promising, cost-effective alternative for portable GC systems, enhancing selectivity and improving the capability of field vapor analysis.