Multi-Reflecting TOF High-Resolution Mass Spectrometer

What is the Multi-Reflecting TOF High-Resolution Mass Spectrometer?

A multi-reflecting TOF folds the ion path between electrostatic mirrors to reach 50 to 100 m flight length in a benchtop housing. Resolving power of 50000 to 100000 and sub-ppm mass accuracy make it suitable for complex mixture screening, petroleomics and isotopic fine-structure work.

Overview

A multi-reflecting TOF uses two opposing gridless ion mirrors, or a multi-turn electrostatic sector, to send ions through many passes, extending path length from 1 to 2 m to 30 to over 100 m without enlarging the instrument. The added flight time increases resolving power from about 20000 to 50000 to 100000 FWHM. Higher resolving power separates isobaric compounds, such as those differing by 3.4 mDa between C3 and SH4, and reveals isotopic fine structure. Mass accuracy is below 1 ppm with internal calibration. The trade-off is reduced acquisition speed, because longer flight times lower the pulser rate to 1 to 10 kHz, and for some designs a limited m/z window per pass, which restricts the simultaneous mass range. Sensitivity is comparable with standard TOF at equal resolution, and the dynamic range is about three to four orders. The configuration is used when routine oa-TOF resolution is insufficient.

How does it work?

In a time-of-flight mass spectrometer, ions are given the same kinetic energy by an accelerating potential of several hundred volts to 20 kV and then drift through a field-free tube. Flight time scales with the square root of m/z, so the detector, a microchannel plate or fast electron multiplier, records ions in order of mass. Resolution depends on flight path length and on correcting initial energy spread. A reflectron, an ion mirror, extends the path and refocuses ions of equal mass but different energies, raising resolution from about 1000 to 20000 or more. MALDI sources pulse ions naturally, while orthogonal acceleration converts continuous ESI or ICP beams into pulses. Time-to-digital converters or fast digitizers at gigahertz rates record the signals.

What are the key features?

• Folded multi-reflecting ion path giving 30 to over 100 m effective flight length
• Resolving power of 50000 to 100000 FWHM in a benchtop footprint
• Sub-ppm mass accuracy supporting elemental composition assignment
• Isotopic fine structure resolution for confirming formulas of complex molecules
• Gridless ion mirrors maintaining transmission through many reflections
• Software for formula assignment, Kendrick mass defect plots and van Krevelen analysis

What are the technical specifications?

A typical multi-reflecting tof high-resolution mass spectrometer configuration offers mass range of m/z 50–2000 (typical), resolving power of 50000–100000 FWHM (m/z 200), mass accuracy (internal calibration) of < 1 ppm RMS, mass accuracy (external calibration) of < 3 ppm, effective flight path of ~30–100 m and acquisition rate of 1–10 Hz at full resolution (typical). Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Multi-Reflecting TOF High-Resolution Mass Spectrometer is used in petroleomics and crude oil characterization, natural organic matter analysis, non-targeted metabolomics and lipidomics, forensic and doping screening and isotopic fine-structure studies. Across the wider TOF-MS class, laboratories also deploy it for microbial identification in clinical microbiology, intact protein and peptide mass analysis and synthetic polymer molecular weight distribution.

Which standards and certifications apply?

Relevant standards and methods include ASTM D7134, ISO 11260, ISO/TS 16940, USP <1052> Biotechnology-Derived Articles, ASTM E2933, ISO 15189, ISO/IEC 17025 and IEC 61010-1. Certification candidates for this model are CE, ISO 9001 manufacturing and IEC 61010-1 safety; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

TOF instruments are sensitive to temperature changes, because drift-tube expansion shifts flight time, so install them in a room stable within ±1 to 2 °C and away from drafts. Calibrate frequently with standards or internal lock mass to sustain mass accuracy below 5 ppm. MALDI systems require matrix preparation, such as alpha-cyano-4-hydroxycinnamic acid or sinapinic acid, and careful target plate cleaning. Detector microchannel plates degrade over time, so monitor gain and plan replacement, usually after several years. Keep the vacuum system leak tight, with analyzer pressure below 10^-6 mbar. Regulated laboratories, particularly those using MALDI for clinical microbiology, should confirm validated databases and software supporting audit trail and access control.

How do I select the right Multi-Reflecting TOF High-Resolution Mass Spectrometer?

Select a multi-reflecting TOF when isobaric interferences or very complex mixtures require resolving power above 50000 and sub-ppm accuracy, and lower acquisition speed is acceptable. Use standard oa-TOF for fast UHPLC. In an RFQ, specify resolving power at a stated m/z and scan speed, mass accuracy conditions and formula assignment software.

How does it compare with other TOF-MS variants?

Select by ionization source and required resolving power. MALDI-TOF suits intact proteins, polymers and microbial identification, where linear mode reaches m/z above 100000 and reflectron mode improves accuracy for peptides. Orthogonal-acceleration ESI-TOF gives accurate mass for LC-MS at rates compatible with UHPLC. Multi-reflecting designs reach resolving power of 50000 to 100000 in a compact footprint for demanding screening. Consider mass accuracy, typically 1 to 5 ppm with calibration, resolution at your m/z range, acquisition rate, and dynamic range, which is narrower than quadrupoles. Decide whether tandem MS is needed, since TOF/TOF adds fragmentation for sequencing. Check software for microbial databases or polymer analysis, calibration strategy, and service support.