MEMBRANE INTERFACE FOR ONLINE SUPERCRITICAL-FLUID EXTRACTION FLOW-INJECTION ANALYSIS

A simple interface between a supercritical carbon dioxide extractor and an on-line liquid-phase analytical system such as flow injection analysis (FIA) or HPLC is described. Previous approaches to on-line coupling of SFE and HPLC utilized either a separate sorbent bed or the HPLC column itself to separate the analyte from CO2 in the extract sample. The former approach eliminates interference from CO2, but requires development of trapping and elution conditions for each analyte. The latter approach suffers from interference by the large volume Of CO2 introduced into the HPLC system. The interface described here uses a membrane phase separator to remove CO2 from the extract sample without the need for HPLC columns, etc., eliminating interferences while quantitatively transferring solutes of all types to the analytical system. The determination of chloramphenicol and penicillin G solubility in supercritical carbon dioxide with analysis time of 2 min is demonstrated with an on-line SFE/FIA system utilizing this interface.