Design of an automated analysis system for the determination of organic compounds in continuous air stream using solid-phase microextraction

Abstract

An automated solid-phase microextraction (SPME) unit coupled to gas chromatography was used to determine organic compounds in air. The target analyte was released from microcapsules into the air at ambient temperature. A fully automated system was designed to facilitate the monitoring of the organic analytes in the continuous air stream. A thin layer of the capsules was prepared by spraying an aqueous solution containing the microcapsules on one side of a glass slide. The slide was exposed to an air stream, which served as a carrier for the analyte vapors. The exposed air was passed through a flow-through cell that was mounted on the autosampler carousel. The SPME assembly, which was fitted with poly(dimethylsiloxane) fiber, was controlled by standard autosampler software. In the dynamic measurement mode, the fiber was inserted in the cell and the analytes partitoned onto the coating. The performance of the sampling device was characterized with respect to mass loading on the fiber, linearity, exposure time and precision. The primary objective of the study was to characterize the release of the pheromone Gossyplure [(Z)-7-(Z,E)-11-hexadecadien-1-ol acetate] from microcapsules. The precision of the SPME method was, in general, less than 7% RSD using 18 repetitive extractions. The method was found to be linear over at least three orders of magnitude. The sampling interval was typically 30 min.