Selective Polymer Materials: Absolute Determiantion of Their Sorption Properties

摘要

Several types of selective materials are frequently used in chemical sensors such as natural antibodies, synthetic host substances (calixarenes, cyclodextrines, etc.) molecularly imprinted mateirals, or conventional polymers. For a systematic development of those materials, their sorption behavior for interesting analyte substances and potentially interfering compounds has to be thoroughly characterized, which can be atime-consuming and error-prone task. Moreover, using the respective sensor principle itself for this characterization an exact relation between the sensor signal and the underlying partition coefficient or sorption isotherm can often not be obtained. In this paper, we present an automated method for the direct determination of polymer/water partition coefficients of volatile organic compounds that consists of an automated fluid handling system, a dedicated partitioning cell and a purge-and-trap gas chromatography (PT-GC) unit. The main applicaiton of this novel system is the characterization of layer materials for infrared evanescent wave spectroscopic (IR-EWS) sensors, however an extension to other problems is conceivable. The whole experimental procedure comprising calibration of the GC system, preparation of test solutions, analyte partitioning, sample analysis, as well as the necessary cleaning steps is performed automatically under computer control. Hence, this system can be operated unattendedly, yielding a reasonable throughput with comparatively low expenditure of human labor.