ICPMS

Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is an analytical technique that combines a plasma source with a mass spectrometer to detect and quantify elements at trace to ultra-trace levels. The sample, typically introduced as an aerosol, is carried by argon into a high-temperature inductively coupled plasma where atoms are atomized and ions are formed. The ions are then transported into the mass spectrometer, where their mass-to-charge ratios are measured, enabling determination of elemental concentrations and isotopic compositions.

Most ICP-MS systems use a nebulizer to generate an aerosol from liquid samples. The aerosol passes through a spray chamber, a transfer conduit, and a plasma torch. An interface region including a sampler and a skimmer cone extracts ions into the high-vacuum mass spectrometer. The mass analyzer, often a quadrupole, a time-of-flight analyzer, or a magnetic sector instrument, separates ions by m/z. Detection is typically via an electron multiplier or similar detector.

ICP-MS provides high sensitivity with detection limits commonly in the parts-per-trillion to parts-per-billion range for many elements. Quantitative results require calibration with multi-element standards and the use of internal standards to correct for instrument drift and matrix effects. Isotope ratio measurements can be used for tracing and geochronology. Interferences, including polyatomic ions, oxide formation, and hydride species, can affect accuracy; techniques such as collision/reaction cells, high-resolution analyzers, and mathematical corrections mitigate these issues.

Applications span environmental monitoring (trace metals in water and air), geology and mining, materials science, food safety, clinical toxicology, and forensics. ICP-MS offers rapid multi-element analysis, wide dynamic range, and isotopic information, but requires expensive equipment, careful maintenance, and skilled operation. Sample preparation often involves digestion or dissolution of solid matrices to bring analytes into solution.