Supercritical Fluids in Chromatography and Extraction

In the mid 1980s supercritical fluid chromatography (SFC) arose with considerable fanfare as the new technique which would shortly "displace HPLC" and become the "universal separation method". After the initial hype had passed, there has still remained a significant group of applications in both chromatography and extraction for which supercritical fluids are the most suitable solvents. These form the basis of this volume, which illustrates the present state of analytical supercritical technology by a collection of review and research papers. Many publications in this field have blurred the boundaries of supercritical fluids, claiming that they filled a gap between gases and liquids and "had the properties of both". This was never true and this book seeks a more rational view of the state of application of supercritical fluids as their position in the analytical laboratory becomes clearer. These papers emphasise that future chromatographers should not be compartmentalised into "gas chromatographers" or "liquid chromatographers" but should view the field as a series of merging separation techniques.

The overall emphasis is on extraction methods, usually as a sample preparation method prior to HPLC or GC analysis, but in some cases the extract is examined directly as the analytical step. This bias on extraction methods reflects the impact of supercritical fluids in the working laboratory. It is therefore an area where advances can have the maximum benefit for the user. The papers on chromatography are diverse and adventurous, covering particularly chiral chromatography and metal complex analysis, where SFC offers particular advantages over existing methods.

Rather than be a separate branch of chromatography or extractions it is clear that the use of solvents above their normal conditions of temperature and pressure, up to and including the supercritical state, will continue to expand the range of analytical methods as part of an overall spectrum of solubility, polarity and volatility properties of solvents and mobile phases. This volume is an important addition to this movement and will help to redress the lack of education in the theory and practice of sample preparation which has been a great limiting factor for SFC and SFE.