Mass-to-charge Ratio

Overview

The mass-to-charge ratio, written m/z, is the fundamental quantity that mass spectrometers measure to characterise ions. It is defined as the mass of an ion divided by the number of elementary charges it carries, and it is the variable against which a mass spectrum is plotted. Because separation in a mass spectrometer depends on how ions respond to electric and magnetic fields, and that response is governed by both mass and charge rather than mass alone, m/z, rather than absolute mass, is the directly observed parameter. For a singly charged ion the m/z value corresponds numerically to the ion's mass, whereas multiply charged ions appear at proportionally lower m/z, producing the charge-state distributions characteristic of electrospray ionisation of large biomolecules. Determining charge state from isotopic spacing or from a series of related peaks allows the true molecular mass to be deduced. Different analysers exploit distinct physical principles to resolve m/z, including time-of-flight, quadrupole, ion-trap, and high-resolution instruments, and the achievable mass resolution and accuracy determine how closely species of similar m/z can be distinguished. Accurate m/z measurement underpins compound identification, molecular-formula assignment, and quantitation across applications such as proteomics, metabolomics, pharmaceutical analysis, clinical diagnostics, and food and environmental testing, making it a central concept in modern mass spectrometry.

Research published in this journal

5 peer-reviewed articles, ranked by relevance. Each links to its DOI.

How this research is being cited

The 5 articles above have been cited 4 times in the scholarly literature. Citation data via OpenAlex and Crossref, updated Jun 2026.

• CFTR-mediated monocyte/macrophage dysfunction revealed by cystic fibrosis proband-parent comparisons
  2022 · JCI Insight
• CFTR-mediated monocyte/macrophage dysfunction revealed by cystic fibrosis proband-parent comparisons
  2022 · JCI Insight
• CFTR-mediated monocyte-macrophage dysfunction revealed by cystic fibrosis proband- parent comparisons
  2021 · medRxiv (Cold Spring Harbor Laboratory)
• CFTR-mediated monocyte-macrophage dysfunction revealed by cystic fibrosis proband-parent comparisons
  X. Zhang et al. · 2021 · medRxiv

A sample of recent works citing this journal's research on Mass-to-charge Ratio, linking to each citing work.

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