This preloaded resin is a useful tool for the synthesis of peptides with a C-terminal aspartic aldehyde. After completion of solid-phase peptide synthesis using standard Fmoc-chemistry, side-chain protecting groups are removed with anhydrous trifluoroacetic acid. The release of the fully deprotected peptide-aldehyde is achieved by treatment with a mixture of acetonitrile/water/trifluoroacetic acid.