ABSTRACT
This chapter discusses the reversed-phase trace enrichment technique. Size-exclusion high-performance liquid chromatography (SEC) is the high performance equivalent of this type of chromatography. SEC columns are packed with uniform, small, and highly porous gels. The effectiveness of the method can be illustrated best by considering the loading of 20 µg of ribonuclease onto the SEC column. Column performance in terms of recoveries and peak shape is identical regardless of volume of loading when reversed-phase trace enrichment was used for the 5 and 50 ml sample volumes. The cartridge pre-column systems available are ideal for trace enrichment. The Guard-Pak cartridge is put in line with the column. The column eluate now passes through the cartridge. Provided that the loading solution is aqueous or of low solvent strength, peptides and proteins enrich onto the ODS-silica cartridge. The experiences demonstrated that the chromatographic efficiency of the Guard-Pak inserts is comparable to that of the Brownlee cartridges.
