Lopez, John, G. de la Torre, Beatriz, Mthethwa, Ndumiso, Rao Manne, Srinivas and Albericio, Fernando (2025) Looking Inside the SPPS Reactor through a Refractometer: Online Quantification of the Resin Loading. Organic Process Research & Development, 29 (2). pp. 411-417. ISSN 1083-61601520-586X

Abstract

The methodology of solid phase peptide synthesis (SPPS) is the main architect of the positive boom that peptides are having in drug discovery. SPPS has many advantages, such as ease of scaling-up, high yields, and short production times. However, it is like a black box as the intermediates are not isolated, and the results are not known until the end of the entire process.
A key point of SPPS is to know the initial loading of the resin. Considering a higher loading compared to the real one will result in the use of a greater excess of reagents with a positive impact on the purity of the final product, but negative in economic terms. On the other hand, in case of lower loading compared to real one, the formation of deletion peptides can take place.
The most frequent method to calculate the loading is incorporating a Fmoc derivative, then removing the Fmoc group with piperidine followed by the UV spectrophotometric determination of the dibenzofulvene-piperidine adduct. This operation requires stopping the synthetic process and consumes time.
Herein, the quantitative use of the refractometry index is proposed to perform the on-line determination of the resin loading. This allows real-time knowledge of the reaction process at all times and to be able to stop the reaction if the loading achieved is the desired one or to add more coupling reagents to improve the loading.

Item Type:	Article
Date Deposited:	17 Jun 2025 00:46
Last Modified:	17 Jun 2025 00:46
URI:	https://oak.novartis.com/id/eprint/55516