Reflectron MALDI-TOF Mass Spectrometer

What is the Reflectron MALDI-TOF Mass Spectrometer?

A reflectron MALDI-TOF adds an ion mirror to the flight path, reaching resolution of 15000 to 25000 and mass accuracy of a few ppm for peptides, oligonucleotides and polymers. It is used for peptide mass fingerprinting, synthetic polymer end-group analysis and quality control of biomolecules.

Overview

A reflectron MALDI-TOF uses a pulsed laser to desorb and ionize analytes from a crystalline matrix, and a reflectron to refocus ions. Delayed extraction of a few hundred nanoseconds corrects for initial velocity spread, and the combined effect lifts resolution to 15000 to 25000 FWHM at m/z 2500, resolving isotopic peaks of peptides and small proteins. Mass accuracy is 5 to 20 ppm with external calibration and below 5 ppm with internal calibration. The instrument runs in linear mode for large molecules above about m/z 30000 and in reflectron mode for lower masses, switching automatically. Laser repetition rates of 1 to 2 kHz allow fast acquisition and imaging at 50 to 100 µm spatial resolution. Fragmentation is limited to post-source decay, so peptide sequencing is weaker than on TOF/TOF instruments. The configuration is well suited to peptide mass fingerprinting, polymer molecular weight distributions and oligonucleotide quality checks.

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?

• Reflectron with delayed extraction achieving 15000 to 25000 FWHM resolution at m/z 2500
• Automatic switching between linear and reflectron modes for wide mass coverage
• 1 to 2 kHz laser with random-walk sample rastering for reproducible spectra
• Internal calibration support with peptide mixtures or polymer standards
• Imaging option for mass spectrometry imaging of tissue sections at 50 µm resolution
• Polymer analysis software calculating Mn, Mw and polydispersity index

What are the technical specifications?

A typical reflectron maldi-tof mass spectrometer configuration offers mass range (reflectron) of m/z 500–30000, mass range (linear) of up to m/z 500000, resolution (reflectron, m/z 2500) of ≥ 15000 FWHM, mass accuracy (internal calibration) of ≤ 5 ppm, mass accuracy (external calibration) of ≤ 20 ppm and laser repetition rate of up to 2 kHz. 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 Reflectron MALDI-TOF Mass Spectrometer is used in peptide mass fingerprinting for protein identification, synthetic polymer molecular weight distribution, oligonucleotide quality control, tissue imaging mass spectrometry and intact mass of small proteins and antibody fragments. 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 Reflectron MALDI-TOF Mass Spectrometer?

Select a reflectron MALDI-TOF when accurate mass of peptides, polymers or oligonucleotides is needed but sequencing by MS/MS is not. Choose MALDI-TOF/TOF for sequencing. In an RFQ, specify resolution at a named m/z, mass accuracy mode, laser rate, imaging option and polymer 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.