PARALLEL-FLOW RESTRICTOR FOR SUPERCRITICAL-FLUID CHROMATOGRAPHY

The flow rate in a capillary SFC column can be kept nearly constant th roughout the entire pressure or density program by the use of a parall el flow restrictor. The mass flow rate of the mobile phase through the column can be controlled by controlling the back-pressure at the end of the column. This was done by adding a parallel flow restrictor to t he end of the column. The degree of restriction may be programmed by t he temperature of the restrictor. The performance of two different typ es of temperature programmable restrictors, i.e., a two-stage restrict or and a parallel flow restrictor were studied and compared.