“Remainders of KM” plot for polymers using msRepeatFinder: compositional mapping over a broad mass range
Mass Spectrometry (MS) with soft ionization such as matrix-assisted laser desorption ionization (MALDI) allows the compositional analysis of polymers (repeating units, chain terminations) of low dispersity. Combining a size exclusion chromatography (SEC) fractionation with a high-resolution MALDI SpiralTOF™ MS analysis enables the evaluation of the composition of polydisperse polymeric samples over a broad mass range (high-resolution/high-accuracy mass measurements in the low mass range < 4 kDa, isotopic resolution in higher mass range < 30kDa). However, as the resolution gets higher, more peaks are detected in the mass spectrum for each fraction, making the interpretation of the mass spectral data the rate-limiting step for the whole analytical procedure. In this work, a “remainders of Kendrick mass” (RKM) analysis is used as a rapid post-acquisition data processing tool that uses visual maps from combined low/high-accuracy and low/high mass range data.
A 1 mg mL-1 solution of poly(ɛ-caprolactone) (PCL, Polymer Source, P1302-CL) in CHCl3 was fractionated by SEC (HLC8220 GPC system, Tosoh, TSKgel multipore HXL-M columns, flow rate: 1 mL min-1, 0.5 mL per fraction). Mass spectra were recorded by using a JEOL JMS-S3000 SpiralTOF™ mass spectrometer (matrix: DCTB, no salt added). The plots were computed by using msRepeatFinder 3.0 (JEOL Ltd.).