Solvent-Free Injection in Supercritical Fluid Chromatography Using Sintered Glass Deposition

Sample injection in supercritical fluid chromatography (SFC) is usually performed using a combination of apparatus from liquid chromatography and capillary gas chromatography. The device most often consists of an injection valve (of the type used in liquid chromatography) followed by a flow splitter controlled by a restrictor. It is sometimes desirable to inject samples in the absence of a solvent, as in physicochemical applications of SFC. In this article, two simple modifications to a conventional sampling valve system are presented which allow solvent-free injection. Using these devices, sample (in a solvent) is deposited on a sintered glass bed. After removal of the solvent by mild heating and evacuation, the sample loop is filled with the supercritical carrier and the valve is switched to the inject position.