ABSTRACT
Sample preparation will involve extraction techniques, concentration procedures and methods for removing solid contaminants that may damage the sample valve, column or some other part of the
chromatograph. The column can often be protected by the use of a pre-column or guard column, but such devices can introduce a significant extra column volume in the chromatographic system, causing further peak dispersion, and thus, impair resolution. If the components of the sample are well separated, then the extra dispersion resulting from the pre-column will not usually affect the separation adversely. If, however, the necessary separation is only just achieved with the phase system selected, then the sample dispersion that would occur in the guard column could well degrade the resolution to a point where its use could not be recommended. In the absence of a guard column, the column proper will only be protected by the cleaning procedure used in the sample preparation procedure prior to loading the column.
