Compositional Analysis of the High Molecular Weight Ethylene Oxide Propylene Oxide Copolymer by MALDI Mass Spectrometry

TL;DR

This study uses MALDI mass spectrometry to analyze the composition of high molecular weight ethylene oxide-propylene oxide copolymer, revealing detailed oligomer distributions and isotopic patterns despite compositional complexity.

Contribution

It demonstrates the application of MALDI MS to resolve and analyze the complex composition of high molecular weight copolymers.

Findings

448 isotopically resolved peaks identified

Oligomers separated by 14 Da

Strong agreement between experimental and theoretical isotopic distributions

Abstract

The composition of narrow distribution poly ethylene oxide-propylene oxide copolymer (Mw ~ 8700 Da) was studied using matrix assisted laser desorption ionization (MALDI) mass spectrometry. The ethylene oxide-propylene oxide copolymer produced oligomers separated by 14 Da. The average resolving power over the entire spectrum was 28,000. Approximately 448 isotopically resolved peaks representing about 56 oligomers are identified. Although agreement between experimental and calculated isotopic distributions was strong, the compositional assignment was difficult. This is due to the large number of possible isobaric components. The purpose of this research is to resolve and study the composition of high mass copolymer such as ethylene oxide-propylene oxide.