Improvement of Mass Spectrometry Imaging Capability in JMS-S3000 "SpiralTOF™-plus"
MSTips No. 304
In matrix-assisted laser desorption/ionization (MALDI), a co-crystal is formed by mixing a matrix solution, which is an ionization promoter, with a sample solution and air drying the solution. The sample molecules are desorbed and ionized by irradiating the co-crystal with an ultraviolet laser. Various organic compounds such as proteins, peptides, nucleic acids, sugars, lipids, drugs, and synthetic polymers can be ionized by selecting an appropriate matrix according to the sample. In MALDI, samples with a wide range of molecular weights are ionized as single-charge ions, and the laser used for ionization is a pulsed laser, it is compatible with a time-of-flight mass spectrometer (TOFMS). Reflectron TOFMS has been widely used as a mass analyzer. However, the mass-resolving power of reflectron TOFMS is often inadequate for analyzing low-molecular-weight molecules, and it has been said that it is not applicable to molecules with a molecular weight of 500 Da or less. In addition to insufficient mass-resolving power, ions derived from post-source decay (PSD), which is spontaneous fragmentation, are detected as noise in the low-m/z region, making the detection of trace components difficult. In 2010, JEOL introduced the MALDI-TOFMS JMS-S3000 "SpiralTOF™" equipped with a unique spiral trajectory ion optical system. "SpiralTOF™" realized a flight distance of 17m in a limited space due to its spiral ion trajectory and achieved ultra-high mass-resolution and ultra-high mass accuracy over a wide mass range. In addition, ions derived from the PSD can be removed by the sector electric field that constitutes the ion optical system, making it easy to detect trace components. This makes it possible to analyze low molecular weight regions, which reflectron TOFMS is not good at, with high mass-resolution and high mass accuracy. In recent years, mass spectrometry imaging (MSI), which can visualize the distribution of organic compounds on the sample surface, has become practical. Many of the target compounds are low-molecular-weight compounds, and the high analysis capability of SpiralTOF™ for low-molecular-weight compounds is a great advantage [1-3]. In the fall of 2019, SpiralTOF™ was renewed to "SpiralTOF™-plus" with enhanced mass spectrometry imaging capabilities while maintaining the feature of high mass-resolving power (Fig. 1). This report introduces the features of SpiralTOF™-plus and its advantages in actual analysis.