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Fraction base-KMD plots for a high-MW - S3000 - MSTips - 283

High molecular weight polymers are often MS-silent due to their inherent high dispersity (DM) or detected in the high mass range with low resolving power. An "on-plate" alkaline degradation has thus been developed as a sample pre-treatment on the MALDI target with tenths of ng of polymer to cut long industrial polyester chains into short oligomers amenable to MALDI-HRMS.

High Sensistivity Analysis of Intact Proteins using Linear TOF

The JMS-S3000 SpiralTOF has a unique 17m flight path that offers then highest resolution MALDI-TOF MS system currently available. However, ions with a very short lifetime or that undergo spontaneous dissociation during their flight cannot be detected by the SpiralTOF (or a conventional reflection TOF). To address this situation, the SpiralTOF with Linear TOF option can be used for the high sensitivity analysis of intact proteins.

“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.

The Relationship between Crystal Condition and Mass Resolving Power, Mass Accuracy

The JMS-S3000 SpiralTOF™ has a unique 17 m flight path that offers the highest resolution MALDI-TOF MS system currently available. With an extended flight distance, the SpiralTOF reduces topographic effect of matrix crystal to a minimum and achieves highly reproducible mass resolving power and high mass accuracy with external mass calibration. In this work, we demonstrate the measurement of a polymer standard with 4 types of matrices that are typically used for MALDI polymer measurement by using the JEOL SpiralTOF system. Additionally, we looked at the crystal condition using the JEOL JSM-7600F thermal field emission scanning electron microscope (FE-SEM).

Measurement of synthetic polymers: Polystyrene

Polystyrene (PS)1000 and 2400 were measured using the JMS-S3000 SpiralTOF. The [M+H]+ peaks of PS with the basic monomer units of 104u (Fig.1) were observed for each sample. The mass spectrum of PS1000 and an expanded view around m/z 1000 are shown in Fig. 2. The resolving power at m/z 1101 was approximately 50,000 (FWHM). The mass difference between 8, 9 and 10-mers showed a very good match with the theoretical mass number (104.0626) calculated from the elemental composition of the repeating unit (C8H8). The mass spectrum of PS2400 and the expanded view of the isotopic pattern of 23-mer are shown in Fig 3. The observed isotopic pattern of the 23-mer is in very good agreement with the simulated isotopic distribution (R 60,000).

Measurement of synthetic polymers: Polymethyl methacrylate

Polymethyl methacrylate (PMMA) 4000 was measured by using the JMS-S3000 SpiralTOF. The [M+H]+ peaks for PMMA with the basic monomer units of 100u (Fig.1) were observed for this sample. The full PMMA mass spectrum and an expanded view around m/z 4000 are shown in Fig. 2(a) and (b), respectively. The resolving power at m/z 4,000 was approximately 45,000 (FWHM). Also, the mass differences between the 39, 40, and 41- mers had a very good match with the theoretical mass number (100.0524) of the PMMA repeat unit (C5H8O2). A comparison between the 40-mer’s observed and simulated isotopic patterns is shown in Fig. 2(c). The observed isotopic pattern is in very good agreement with the calculated isotopic distribution.

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Corona - Glow Discharge (DART Ion Source)

February 22, 2020
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