Analytical Instrument Documents

JEOL introduced the DART ion source in 2005, and the technology quickly gained recognition, winning both the Pittcon Editor’s Gold Award and the R&D 100 Award. Since that time nearly 400 papers have been published by chemists using the AccuTOF-DART. The introduction of DART made it possible for the first time to carry out atmospheric pressure ionization for analysis of samples in open air.

In many fields such as clinical diagnosis and food inspection, there is a demand for rapid, reliable and simple-to-use methods for characterizing bacteria. This paper explores the use of two new and innovative instruments called ClairScope™ and SpiralTOF™ for this rapid characterization. The JASM-6200 ClairScope™ integrates an optical microscope (OM) with a scanning electron microscope (SEM) where it is possible to observe samples in solution, in an open system, by the SEM at atmospheric pressure. This type of sample would typically require extensive sample pretreatment that would take a day or more with conventional SEM techniques. With the recently developed ClairScope™, fine morphological observation can be performed directly in solution with simple sample pretreatment of one hour or less. The JMS-S3000 SpiralTOF™, is a matrix-assisted laser desorption/ionization mass spectrometer (MALDI-MS) with a spiral ion trajectory. With sample pretreatment as fast as a few minutes, the SpiralTOF™ can characterize ribosomal proteins and phospholipids with high accuracy. Ribosomal proteins are biomarkers for phylogenetic classification, and phospholipids are used for chemotaxonomic analysis. The combination of ClairScope™ and SpiralTOF™ are found to be powerful instruments for the characterization of bacteria.

A gas-chromatograph mass spectrometer (GC-MS) is a combined analyzer that has superior ability in analyzing organic compounds qualitatively and quantitatively. The first part, gas chromatograph, separates the compounds included in a sample (mixture), then the second part, mass spectrometer, obtains mass spectra of the compounds to carry out qualitative analysis. Quantitative analysis can be carried out as well from the peak area of the mass chromatogram of the compound. As a mass spectrometer of a GC-MS system, several types of mass spectrometers are on the market, such as magnetic field, quadrupole (QMS), ion trap (ITD), and time-of-flight (TOF). Each mass spectrometer has its own features and applications.

We have developed the JMS-S3000, matrix assisted laser/desorption ionization time-of-flight mass spectrometer (MALDI-TOFMS). An innovative ion optical system, which achieved a spiral ion trajectory, surpassed basic specification of the reflectron ion optical system presently used in most commercially available TOFMSs. Furthermore, we have developed the TOF-TOF option for the JMS-S3000. In the case of attaching the TOF-TOF option, a spiral ion optical system is adopted for the first TOFMS, whereas a reflectron ion optical system with offset parabolic reflectron is adopted for the second one. Utilizing the spiral trajectory ion optical system, the JMS-S3000 provides unprecedentedly high mass resolution and high precursor ion selectivity. In this paper, we demonstrate not only the high mass resolution of more than 60,000 (FWHM) at m/z 2093 but also achievement of high mass resolution over a wide mass range. In addition, we present the high selectivity that enables selection of monoisotopic ions of precursor ions. By selecting only monoisotopic ions of precursor ions, one signal peak corresponding to each fragmentation channel is observed on a product ion spectrum. Consequently, the analysis of the product ion spectrum is made clearer.

Laser Desorption/ Ionization-Time of Flight Mass Spectrometry (LDI-TOFMS) is generally used for analysis of organic compounds because this technique generates little fragmentation of molecular ions at ionization. It makes possible to obtain information on molecular weights and molecular structures in organic compounds. In particular, a technique which uses the matrix compounds for enhancing ionization efficiency is well known as Matrix-Assisted Laser Desorption/ Ionization-Time of Flight Mass Spectrometry (MALDI-TOFMS). This technique is widely used in the bio markets owing to its capability of ionizing proteins and peptides with the molecular weights of several thousands to several hundreds of thousands. The MALDI-TOFMS is also utilized for analysis of synthetic polymers. In many cases, LDI-TOFMS and MALDI-TOFMS have been used to estimate the molecular weights of organic compounds in solution. But very recently, techniques of imaging mass spectrometry, which controls the laser irradiation position by two-dimensional scan to acquire mass spectra for visualizing localization of chemical compounds with specific molecular weights, have been improved. The application of this innovative technique is increasingly spreading in the bio markets. The technology of Imaging Mass Spectrometry has been advancing for analyzing biological tissue sections, but in the future, it is expected to develop toward the material science markets. It is noted that various surface analytical techniques are already available in the material science markets. In order to study the advantages of LDI-TOFMS as one of effective surface analysis tools, it is essential to consider the complementary analysis of LDI-TOFMS with the existing surface analytical techniques. In this article, the advantages of using LDI-TOFMS for analyzing organic lightemitting diode material thin films, in accordance with comparison with Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy/Energy-Dispersive X-Ray Spectroscopy (SEM/EDS), have been studied. In addition, since LDI-TOFMS is a destructive analytical technique, the influence on the sample surface caused by LDI-TOFMS was also examined.

All mass spectrometers combine ion formation, mass analysis, and ion detection. This discussion is concerned with how various mass analyzers are used to separate ions according to their massto- charge ratio. Each mass analyzer has its own special characteristics and applications and its own benefits and limitations. The choice of mass analyzer should be based upon the application, cost, and performance desired. There is no ideal mass analyzer that is good for all applications. For an excellent and more complete discussion of mass analyzers, see "The Ideal Mass Analyzer: Fact or Fiction?" (Curt Brunnee, Int. J. Mass Spectrom. Ion Proc. 76 (1987), 125-237.

A mass spectrometer works by using magnetic and electric fields to exert forces on charged particles (ions) in a vacuum. Therefore, a compound must be charged or ionized to be analyzed by a mass spectrometer. Furthermore, the ions must be introduced in the gas phase into the vacuum system of the mass spectrometer. This is easily done for gaseous or heat-volatile samples. However, many (thermally labile) analytes decompose upon heating. These kinds of samples require either desorption or desolvation methods if they are to be analyzed by mass spectrometry. Although ionization and desorption/desolvation are usually separate processes, the term "ionization method" is commonly used to refer to both ionization and desorption (or desolvation) methods. The choice of ionization method depends on the nature of the sample and the type of information required from the analysis. So-called 'soft ionization' methods such as field desorption and electrospray ionization tend to produce mass spectra with little or no fragment-ion content.

Double-focusing magnetic sector mass spectrometers provide high sensitivity, high resolution, and a reproducibility that is unmatched in any other kind of mass analyzer.

Tandem mass spectrometry is a powerful tool for polymer characterization. It can obtain information about polymer end groups, repeating structures (linear, cyclic, or branched), and copolymerization. High-energy collision–induced dissociation (HE-CID) is a fragmentation method that is available only in tandem time-of-flight mass spectrometry (TOF–TOF). The informative fragmentation channels, which are difficult to observe with commonly used low-energy CID, are often observable in HE-CID spectra. In MSTips 270, we proposed a method to visualize this abundant structural information and enable intuitive analysis using the “Remainders of KM” (RKM) plot method. In this report, we applied the method to analyze polyethylene oxide (PEO) with different end groups.

The JMS-S3000 “SpiralTOF™” is a MALDI-TOFMS that incorporates an innovative SpiralTOF ion optics system. This system is available with a TOF-TOF option that can acquire high-energy collision-induced dissociation (CID) product ion spectra for monoisotopically selected precursor ions. In this work, we analyzed Poly Methyl Methacrylate (PMMA) shown in Fig. 1 by using the JMS-S3000 SpiralTOF with the TOF-TOF option. The resulting high-energy CID data was then processed using the Polymerix™ (Sierra Analytics, Inc., http://massspec. com/) analysis software.