To completely clean the resin after a deprotection or coupling reaction, the beads are typically washed four to six times with solvent. The typical protocol for washing is:

1. Fill the reaction vessel with approximately 10mL of solvent (DMF, NMP) per 0.5g of resin.

2. Bubble the mixture for several seconds.

3. Immediately drain the reaction vessel through the filter.

Repeat steps 1-3 a minimum of four times.

Sign of Poor Washing

Amino Acid Addition - if the peptide product contains an amino acid insertion in the sequence, this could indicate poor washing. This could be caused by piperidine remaining in the reaction vessel during the coupling reaction or activated amino acid during the deprotection reaction.

If this problem occurs:

1. Increase the wash cycles between each reaction.

2. Check the spray head in the top of the reaction vessel to ensure washing of the vessel walls