Quick and efficient desalting, buffer exchange, removal of dyes and small molecules from proteins greater than 25 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.