Analytical Instrument Documents

Matrix assisted laser desorption ionization (MALDI) is a powerful and useful ionization technique that is commonly used for the analysis of biomolecules such as oligosaccharides. There are many applications of oligosaccharides in which various ionization techniques and mass spectrometers were used for their analysis [1]. In particular, tandem mass spectrometry techniques are often used to sequence these molecules. Recently, JEOL developed a new tandem TOF-TOF instrument coupled with MALDI that is called the Spiral- TOF. The 1st TOF consists of 4 toroidal electric sectors that fold a 17 meter flight path into a one meter box. This design provides several unique advantages for TOF-TOF analysis. The 2nd TOF has (a) 20 kV high-energy CID, (b) monoisotopic precursor ion selection, and (c) no PSD ions in the product ion mass spectrum. In this study, we analyzed several oligosaccharides by using the JMS-S3000 SpiralTOF-TOF tandem mass spectrometer system.

Lysine and glutamine are not easily distinguished by the most common approaches to peptide sequencing which involve mass spectrometers with low to moderate resolving power and low-energy collision-induced dissociation (CID). Lysine (C6H14N2O2 with a mass of 146.1055 u) and glutamine (C5H10N2O3 with a mass of 146.0691) differ by only 0.036 u. In this study, we demonstrate the measurement of a mixture of Substance P and a synthesized peptide (3-Gln ) with glutamine substituted for lysine in the Susbstance P sequence. Because the mass difference between Substance P and 3-Gln is 0.036 u, a resolving power of greater than 37,000 is required to separate each peptide. Additionally, we show that the TOF-TOF mode can be used to distinguish lysine and glutamine in these peptides by comparing the peak area ratio between a ions and d ions in the high-energy CID mass spectra.

The JMS-3000 SpiralTOF™ has an optional TOF-TOF mode that features monoisotopic precursor ion selectivity, elimination of post source decay (PSD) ions, and high energy collision induced dissociation (CID). The JMS-700T MStation four-sector tandem double focusing mass spectrometer, although featuring a different analyzer and ionization techniques, has similar capabilities that have been previously used for a wide variety of applications including the structural analysis of complex biological molecules. In this work, we compare the SpiralTOF-TOF with the MStation four sector tandem double focusing mass spectrometer using the same sample for MS/MS analysis.

Yessotoxin (YTX) is one of the substances that cause food poisoning when humans consume toxic shellfish. The structure of this compound has been previously analyzed by high-energy collision induced dissociation (CID) using a traditional four sector tandem double focusing mass spectrometer. In this work, we analyzed YTX by using a JMS-S3000 SpiralTOF™ equipped with the optional TOF-TOF analyzer to generate a high energy CID product ion spectrum.

Sperm activating and attracting factor (SAAF) is a naturally occurring substance produced by ascidians (sea squirts) to promote the fertilization process. Previously, the structure of this compound was characterized by high-energy collision induced dissociation (CID) using a traditional four sector tandem double focusing mass spectrometer. In this work, we analyzed the SAAF from a ciona intestinalis by using a JMS-S3000 SpiralTOF™ equipped with the optional TOF-TOF analyzer to generate a high energy CID product ion spectrum for this compound.

Phosphorylation is a type of post-translational modification of proteins that is used for the intracellular signal transduction in a wide range of living species. For this reason, it is very important to determine where the protein (amino acid) is phosphorylated. In this work, we measure a monophosphopeptide (FQ pS EEQQQTEDELQDK) that was obtained from the tryptic digestion of β-casein (Bovine) using the TOF-TOF option that is available for the JEOL Spiral- TOF™ system.

Industrial materials are often evaluated by surface analysis instruments that provide information on surface elements, bonding states, and functional groups. However, there are limited options for surface analysis techniques that provide molecular weight and molecular structure information for organic compounds present on surfaces. Matrix Assisted Laser Desorption Ionization - Time of Flight Mass Spectrometry (MALDI-TOFMS) is a soft ionization technique that can be used to analyze surfaces in order to estimate elemental compositions with accurate mass measurements, obtain structural information by using MS/MS, and map surface compounds by using MS imaging. MALDI-TOFMS uses a high voltage on the target plate to accelerate the ions into the TOFMS analyzer. Therefore, the target plates are conductive and are typically made of stainless steel. MALDI imaging mass spectrometry is widely used for analyzing organic substances on frozen tissue sections. In this case, a frozen tissue section with a thickness of about 10 μm is placed on a conductive glass slide coated with an indium tin oxide (ITO) film. However, for the analysis of industrial products, the target organic compounds are on nonconductive substrates such as resins with millimeter thicknesses. MALDI-TOFMS surface measurements using nonconductive substrates lead to a reduction in mass resolution and a significant decrease in ion intensity due to surface charging. This problem can be solved by pretreating the surface with gold vapor deposition in order to change it from nonconductive to conductive. This method was previously shown to work well in MSTips No. 204 in which the gold vapor deposition method was applied to the MALDI-MS imaging analysis of inks on paper. In this report, we used gold vapor deposition to look at samples on the surface of a 1 mm thick acrylic plate.

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 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).

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    January 28, 2022
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