Quick and efficient desalting, buffer exchange, removal of dyes and small molecules from proteins greater than 5 kD with minimal dilution. Purified proteins are eluted into Phosphate Buffered Saline (PBS, pH 7). The gel bed has a volume of 0.8 ml. Samples with a volume of between 10 and 100 μl can be processed. Optimal purification and recovery is obtained with a sample volume of 50 μl.