An Automated Analysis\nof Homocoupling Defects Using\nMALDI-MS and Open-Source Computer Software

Conjugated\norganic polymers have substantial potential for multiple\napplications but their properties are strongly influenced by structural\ndefects such as homocoupling of monomer units and unexpected end-groups.\nDetecting and/or quantifying these defects requires complex experimental\ntechniques, which hinder the optimization of synthesis protocols and\nfundamental studies on the influence of structural defects. Mass spectrometry\noffers a simple way to detect these defects but a manual analysis\nof many complex spectra is tedious and provides only approximate results.\nIn this work, we develop a computational methodology for analyzing\ncomplex mass spectra of organic copolymers. Our method annotates spectra\nsimilarly to a human expert and provides quantitative information\nabout the proportions of signal assigned to each ion. Our method is\nbased on the open-source Masserstein algorithm, which we modify to\nhandle large libraries of reference spectra required for annotating\ncomplex mass spectra of polymers. We develop a statistical methodology\nto analyze the quantitative annotations and compare the statistical\ndistributions of structural defects in polymer chains between samples.\nWe apply this methodology to analyze commercial and lab-made samples\nof a benchmark polymer and show that the samples differ both in the\namount and in the types of structural defects.