WHAT IT IS
Mass Spectrometry (MS) is a universal analytical technique used to measure the mass-to-charge ratio (m/z) of ions. It provides molecular weight, isotopic composition, elemental information, and structural data. MS is applied to organic and inorganic compounds, biomolecules, isotopes, and materials, making it one of the most widely used methods in modern science.
HOW IT WORKS
Sample Introduction – The sample is introduced in gaseous, liquid, or solid form.
Ionization – Neutral species are converted into ions using a suitable ion source.
Ion Transfer – Ion optics focus, steer, and accelerate ions into the highvacuum regions of the instrument.
Mass Analysis – Ions are separated by m/z in a mass analyzer.
Detection – Separated ions are measured by a detector, producing signals proportional to abundance; multicollector detectors enable precise isotope ratios.
Spectrum Generation – Signals are compiled into a mass spectrum (intensity vs m/z), whose peaks correspond to molecular ions, fragments, isotopologues, or elemental ions.
TYPES OF MS INSTRUMENTS
Analyzers
Quadrupole – mass filtering by dynamic electric fields; compact, robust, and cost-effective for routine, selective quantification.
Triple Quadrupole (QQQ) – tandem quadrupole architecture enabling collision-induced reactions and highly selective, lowlevel quantification via defined ion transitions.
Time-of-Flight (TOF) – separation by flight time after pulsed acceleration; delivers high speed, wide mass range, and accurate mass capability.
Ion Trap – storage and sequential manipulation of ions in radio-frequency fields; supports multistage MS for structural elucidation.
Orbitrap – electrostatic trapping with image-current detection; provides high resolution and accurate mass for complex mixtures.
FT-ICR – cyclotron motion detection in strong magnetic fields; affords ultrahigh resolving power and sub-ppm mass accuracy for extremely complex spectra.
Magnetic Sector – momentum/energy focusing with magnetic/electrostatic sectors; gold standard for precise isotope ratios and high-accuracy elemental data.
Hybrid Analyzers – combinations such as QTOF or Q-Orbitrap; couple selectivity with high-resolution accurate-mass measurements.
Instrument Families
Hyphenated MS (GC-MS, LC-MS, etc.) – integrated platforms that combine separation techniques with MS; the most common systems in analytical chemistry, biology, and pharmaceuticals.
ICP-MS – plasma-based instruments for trace and ultra-trace element detection and isotope studies.
SIMS – ion beam systems for sputtering solid surfaces; provide elemental and isotopic imaging and depth profiles at micro- to nanometer scales.
Isotope MS ( IRMS, Noble Gas MS, TIMS, AMS) – a family of instruments specialized in precise isotope ratio analysis.
Residual Gas Analyzer (RGA-MS) – compact quadrupole systems for continuous monitoring of residual gases in vacuum environments.
Portable / Field MS – miniaturized instruments for on-site and field analysis, extending MS capability beyond the laboratory.
ADVANTAGES
Broad applicability across sample types and disciplines.
High sensitivity with ultra-trace detection limits.
High resolution and specificity for complex mixtures.
Provides both identification and quantification in one analysis.
Compatible with many separation and surface analysis methods.
CHALLENGES AND LIMITATIONS
Instruments are complex and expensive.
Ionization efficiency varies between compounds.
Matrix effects and interferences may distort results.
Data-rich outputs require advanced interpretation tools.