Analytical Instrument Documents

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).

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).

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.

Polyethylene glycol (PEG) 1000 and 8000 were measured by using the JMS-S3000 SpiralTOF. The [M+H]+ peaks for PEG with the basic monomer units of 44u (Fig. 1) were observed for each sample. The mass spectrum for PEG1000 and an expanded view around m/z 1,000 are shown in Fig. 2. The resolving power at m/z 1009 is approximately 60,000 (FWHM). The mass difference between the 21, 22 and 23-mers showed very good agreement with the theoretical mass of the PEG monomer. The full mass spectrum for PEG8000 is shown in Fig. 3(a). The comparison between the observed and simulated isotopic pattern (R 35,000) for the 226mer are shown in Fig. 3(b). The observed isotopic pattern is in very good agreement with the calculated isotopic distribution.

A high-quality mass calibration is required to achieve highly accurate mass measurements by mass spectrometry. A polymer or a mixture of peptides is commonly used to calibrate a MALDI-TOF MS system. However, peptides do not necessarily have long-term stability, and a monodisperse polymer does not have a wide m/z range. Sometimes these standards are not well suited for calibration over a wide m/z range. We used a new dendritic MS calibrant (SpheriCal®) to resolve these issues. Here we demonstrate measurement and calibration using the new calibrant with the JEOL SpiralTOF MALDI mass spectrometer.

Matrix assisted laser desorption/ionization (MALDI) combined with in-source decay (ISD) is a useful tool for doing top-down sequencing of intact proteins. In this work, we measured and compared the ISD fragment ions generated for several proteins by using both the high resolution MALDI-Spiral mode and the high sensitivity MALDI-Linear mode available on the JEOL SpiralTOF MALDI-MS system.

The SpiralTOF’s unique multi-turn ion optics package a very long (17-meter) flight path within a 1-meter space. Electric sectors and Matsuda plates provide perfect focusing to eliminate ion loss due to beam divergence. Post-source decay fragments occurring in the flight path are eliminated by the ion optics, providing a clean and artifact-free background.

Matrix assisted laser desorption ionization (MALDI) is a powerful and useful ionization technique that is commonly used for the analysis of biomolecules such as peptides and proteins. Typically, α-Cyano-4-hydroxycinnamic acid (CHCA) is the matrix used for MALDI peptide measurement. Recently, a new matrix “α-Cyano-4-chlorocinnamic acid (CClCA)” was investigated for peptide analysis [1]. In this study, we demonstrate the measurement of a BSA digest to evaluate the improvement in peptide sensitivity with CClCA in comparison with CHCA by using the JMSS3000 SpiralTOF MS system.

Matrix assisted laser desorption/ionization (MALDI) combined with in-source decay (ISD) is a useful tool for doing top-down sequencing of intact proteins. This technique can provide enough information to determine both N- and C-terminal sequences. In this work, we measured the ISD fragment ions generated for several peptides using the JEOL SpiralTOF MALDI-MS system.

High molecular weight polymers are often MS-silent due to their inherent high dispersity (ĐM) or detected in the high mass range with low resolving power. High-resolution mass spectrometry (HRMS) is indeed limited to the low mass range (< 3000 Da) for an unambiguous evaluation of the nature of repeating units and/or end-groups or the isolation of isobaric compounds. 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 [1]. The complexity of the associated mass spectra can be greatly reduced with the appropriate resolution-enhanced Kendrick mass defect (KMD) analysis using the “fraction base” option of msRepeatFinder to produce compositional maps.

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