Apparatus and method for simultaneous supercritical fluid extraction and

Abstract

A system and method for carrying out supercritical fluid extraction and gas chromatography simultaneously. Sample substances contained in solid (or liquid) matrices are extracted by means of supercritical fluid extraction and carried directly onto a thermal desorption modulator which functions as an interface between the extraction and chromatography systems. Analytes carried by the supercritical fluid are retained in the modulator while the fluid passes through during the cool cycle of the modulator. A thermal pulse raises the temperature of the modulator and releases retained substances, serving as a sharp injection of such substances into a fast separating column to provide high-speed separations. A complete chromatogram with reasonable resolution is generated within a few seconds time period. Thermal modulation signals at a fixed time interval are so chosen that the consequent chromatograms do not interfere with one another. A series of high-speed chromatograms are generated during one extraction, and the extraction and the chromatography are carried out simultaneously. Assemble signal averaging provides a higher signal to noise ratio. Segmented signal averaging of a number of consecutive chromatograms generated from one extraction is similar to off-line fraction collection, but the speed of analysis is substantially enhanced without sacrificing analytical accuracy.