Use of an internal reference for the quantitative HPLC-UV analysis of solid-phase reactions: A case study of 2-chlorotrityl chloride resin

Here we evaluated the use of internal reference compounds for the rapid assessment of reactions performed in solid-phase. An internal reference compound (commercially available) was bound to the resin, together with the substrate, and cleaved with the products after completion of the reaction. The peak area of the reference compound in the HPLC-UV chromatograms can be correlated directly with those of other compounds present in the reaction mixture, thereby allowing a quantitative interpretation of the chromatograms with respect to conversion and yield. The usefulness of this method was demonstrated by optimization of a protocol for the synthesis of proline-based tripeptides.