Qualitative supercritical fluid extraction coupled to capillary gas chromatography

Abstract

The usefulness and ease of utilizing supercritical fluid extraction (SFE) directly coupled to capillary gas chromatography (GC) as quantitative or qualitative analytical problem‐solving tools will be demonstrated. As an alternative to conventional liquid solvent extractions, SFE presents itself as a means to achieve high extraction efficiencies of different compounds in complex solid matrices in very rapid tims frames. Moreover, SFE has an additional advantage of being able to achieve distinct extraction selectivities as a function of the solubilizing power of the supercritical fluid extracting phase. For on‐line SFE/GC, the extraction effluent is directly transferred to the analytical chromatograph. On‐line SFE/GC involves the decompression of pressurized extraction effluent directly into a heated, unmodified capillary split injection port of the GC. In this respect, SFE introduction into GC can be used as an alternative means of GC injection, comparable to such modes of injection as pyrolysis and thermal desorption. This paper will show applications of SFE/GC where mass spectrometric detection together with flame ionization detection was used for component identification from environmental, tobacco, and petroleum matrices.

Supercritical fluid chromatography and extraction

“…A detection limit of 30 pg for PCBs was restricted by the purity of available C02 supplies. Quantitative issues surrounding SFE/GC are addressed by Hawthorne (355), and Levy et al discussed qualitative ana quantitative aspects of SFE/GC (356,357).…”

Sample Preparation for Chromatographic Analysis

“…Although neglected by analytical chemists, during the same period supercritical fluid extraction gained acceptance and found many applications as an industrial scale process technique, used for example, to decaffeinate coffee and to extract nicotine from tobacco [98,246]. In contemporary practice, however, the main use has been in combined techniques in which supercritical fluid extraction using a micro-extractor is coupled on-line to gas, liquid, thin-layer or supercritical fluid chromatography [223,[248][249][250][251][252][253][254][255][256][257]. In contemporary practice, however, the main use has been in combined techniques in which supercritical fluid extraction using a micro-extractor is coupled on-line to gas, liquid, thin-layer or supercritical fluid chromatography [223,[248][249][250][251][252][253][254][255][256][257].…”

“…Supercritical fluid extraction can be coupled directly to GC by depressurizing the supercritical fluid extract inside a conventional split/splitless injector or by inserting the extraction cell restrictor through an on-column injector into the capillary column itself [250][251][252]255,257,[263][264][265][266]. The sample extracts are cryogenically focused at the head of the GC column during the extraction step, and the subsequent GC separation is performed in the usual way.…”

Analysis of Highly Volatile Components of Foods by Off-Line SFE/GC

“…So far, coupling SFE on-line with gas chromatography (GC) is the most used approach, because this provides high potential to automate operation and rapid analysis (Vannoort et al, 1990). The coupling has been accomplished by using different interfaces that involved the direct insertion of the SFE restrictor capillary into the GC column using an on-column (Hawthorne and Miller, 1987;Hawthorne et al, 1989) or split-splitless (Hawthorne et al, 1990;Levy et al, 1990Levy et al, , 1991 injection port. Also, a direct interface to a temperatureprogrammable vaporizer (PTV) has been suggested (Houben et al, 1990;Huston and Ji, 1991).…”