Capping step

Abstract

Aspects of the disclosure relate to methods and systems for solid phase oligonucleotide synthesis (SPOS). In some embodiments, the methods described by the disclosure comprise a step of capping reaction solution recycling. In some embodiments, recycling the capping reaction solution requires a significantly reduced amount of capping solution during the entire SPOS process relative to SPOS processes where the capping step of each cycle is carried out using fresh oxidation solution. In some embodiments, oligonucleotides produced using systems and methods of the disclosure have higher purity than oligonucleotides produced using conventional SPOS techniques.