Separation Strategies for Environmental Pollutants. Theory and Practice
Sample preparation is often the most time-consuming step in chromatographic analysis. In many applications, analytes must be determined in complicated matrices, such as soil, sludge, blood, fuel oils and food in very low concentration. Liquid-liquid extraction (LLE) is the traditional method of treating samples. The LLE procedure generally requires several steps, making the cleanup process difficult to automate (i.e. Soxhlet extraction), highly purified solvents that are required, are expensive and many of these solvents are suspected of endangering the health of laboratory workers. Several alternative methods which reduce or eliminate the use of solvents are now being used to prepare samples for chromatographic analysis. These include static and dynamic headspace analysis for volatile compounds, solid-phase extraction (SPE) and supercritical fluid extraction (SFE) for semivolatiles or non volatile pollutants. Recently a new variation of SPE has been developed: solid-phase microextraction (SPME). This technique is normally used prior for GC analysis.