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. 2020 Aug;34 Suppl 2(Suppl 2):e8654.
doi: 10.1002/rcm.8654. Epub 2020 Feb 12.

Automatic peak assignment and visualisation of copolymer mass spectrometry data using the 'genetic algorithm'

James S Town  1 , Yuqui Gao  1 , Ellis Hancox  1 , Evelina Liarou  1 , Ataulla Shegiwal  1 , Christophe J Atkins  1 , David Haddleton  1
Affiliations

Automatic peak assignment and visualisation of copolymer mass spectrometry data using the 'genetic algorithm'

James S Town et al. Rapid Commun Mass Spectrom. 2020 Aug.

Abstract

Copolymer analysis is vitally important as the materials have a wide variety of applications due to their tunable properties. Processing mass spectrometry data for copolymer samples can be very complex due to the increase in the number of species when the polymer chains are formed by two or more monomeric units. In this paper, we describe the use of the genetic algorithm for automated peak assignment of copolymers synthesised by a variety of polymerisation methods. We find that in using this method we are able to easily assign copolymer spectra in a few minutes and visualise them into heat maps. These heat maps allow us to look qualitatively at the distribution of the chains, by showing how they alter with different polymerisation techniques, and by changing the initial copolymer composition. This methodology is simple to use and requires little user input, which makes it well suited for use by less expert users. The data outputted by the automatic assignment may also allow for more complex data processing in the future.

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Figures

Figure 1
Figure 1
Flow chart of the Matlab script utilised in this work
Figure 2
Figure 2
Methyl acrylate‐co‐ethyl acrylate 50/50 mol% synthesised by photomediated SET‐LRP MALDI‐TOF‐MS (left), structure of methyl acrylate‐co‐ethyl acrylate with a substituted thiol end group (top right), and heat map produced from the data (bottom right)
Figure 3
Figure 3
Heat maps visualising the data for methyl‐acrylate‐co‐ethyl acrylate statistical copolymers with ratios of 50/50 (top), 70/30 (middle), and 90/10 (bottom)
Figure 4
Figure 4
60/40 methyl acrylate‐co‐ethyl acrylate statistical copolymer synthesised by photomediated SET‐LRP, showing the issue of misassignment of isotopic peaks
Figure 5
Figure 5
50/50 methyl acrylate‐co‐ethyl acrylate statistical copolymer synthesised by copper(0) wire (top) and photomediated Cu(II) (bottom) SET‐LRP
Figure 6
Figure 6
Methyl methacrylate‐co‐ethyl methacrylate diblock full spectrum; the part that is zoomed shows the overlapping of isotopic distributions between different species
Figure 7
Figure 7
Methyl methacrylate‐co‐ethyl methacrylate diblock, synthesised by catalytic chain transfer polymerisation and sulphur‐free reversible addition‐transfer chain‐transfer polymerisation. Isotopic intensity issue shown (top), and then resolved (bottom)
Figure 8
Figure 8
Styrene‐co‐methyl methacrylate statistical copolymer synthesised by bulk free radicals, using AgTFA (left) and NaI (right) as a cationising agent
See this image and copyright information in PMC

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