Methods and system for solid phase peptide synthesis are provided. Solid phase peptide synthesis is a known process in which amino acid residues are added to peptides that have been immobilized on a solid support. New amino acid residues are added via a coupling reaction between an activated amino acid and an amino acid residue of the immobilized peptide. Amino acids may be activated using, e.g., a base and an activating agent. Certain inventive concepts, described herein, relate to methods and systems for the activation of amino acids. These systems and methods may allow for fewer side reactions and a higher yield compared to conventional activation techniques as well as the customization of the coupling reaction on a residue-by-residue basis without the need for costly and/or complex processes.