Charged species moving in viscous media move at varying rates under the influence of electric fields, dependent on the acceleration due to the field competing with the drag of the medium. A device which measures the relative speed of motion of different ions is an ion mobility spectrometer. In this research, supported by the Analytical and Surface Chemistry Program of the Chemistry Division, Prof. McMinn will use an ion mobility spectrometer to identify and quantify trace organic species. The species will be separated from the medium in which they are initially found by supercritical fluid extraction. The work will be performed largely by undergraduates. Selectivity for organic species will be achieved both by varying the properties of the supercritical fluid used for extraction and by varying the parameters of the ion mobility spectrometer. This two-dimensional approach will give enhanced selectivity compared to either method alone. Both supercritical fluid extraction and ion mobility spectrometry are relatively new techniques. Thus, their combination will afford types of separations and specific analytical methods heretofore unexplored.
