In peptide purification, sample loading onto the column is rarely considered. Most, if not all, HPLC instruments come equipped with a sample injection loop which demands a liquid injection of the sample for purification. If you decide to use flash chromatography to purify your peptides though, liquid injection is no longer the exclusive method for sample introduction to the column. Alternatively, dry loading crude material is a strategy often used in small molecule purification, particularly when sample solubility concerns arise.
The first question I asked myself when considering a new sample loading strategy is whether or not the purification efficiency will be maintained. A close second though is whether or not the loading method will cause significant differences in peptide recovery.
In today's post, I'll compare recovery efficiencies for peptides purified using reversed phase flash chromatography but loaded onto the cartridge using either direct liquid injection or dry loaded onto reversed phase material.