Collision and Reaction Cell (CRC)
Definition
A pressurised cell between the skimmer and the quadrupole, charged with helium for kinetic-energy-discrimination collision mode or with hydrogen, ammonia or oxygen for chemical-resolution mode. Helium knocks larger polyatomics off course; reactive gases convert or mass-shift the interference. The CRC is what made quadrupole ICP-MS routine for arsenic, selenium and chromium in real matrices.
- Location
- Between the skimmer and the quadrupole
- Collision gas
- Helium (kinetic energy discrimination)
- Reaction gases
- Hydrogen, ammonia, or oxygen
- Target analytes
- Arsenic, selenium, chromium in complex matrices
Common questions
What problem does the CRC actually solve in ICP-MS?+
Polyatomic ions formed from the plasma and sample matrix can have the same mass-to-charge ratio as the analyte of interest, producing a false signal. The CRC removes or shifts these interferences before ions reach the quadrupole, so the measured signal reflects the true analyte.
Why does the choice of gas matter?+
Helium collision mode works by physical size, larger polyatomic clusters lose more energy in collisions and are filtered out kinetically, while reactive gases chemically convert or mass-shift a specific interference, so the operator selects the gas mode based on which element and interference are being targeted.
Related terms
- Inductively Coupled Plasma (ICP)
- An argon discharge sustained at 6000 to 10000 K by an RF coil at 27.12 MHz wrapped around a quartz torch. Argon...
- Isotope Ratio Analysis
- Measurement of relative abundances of two or more isotopes of an element to 0.01 to 0.5 percent precision. Lead ratios fingerprint the...
- Optical Emission Spectrometry (OES)
- Detection arm in which excited atoms emit photons at characteristic wavelengths as they relax. A polychromator separates the light by wavelength and...
- Polyatomic Interference
- An ion formed in the plasma at the same nominal mass as a target analyte, for example argon-oxide on iron-56, argon-chloride on...
- Quadrupole ICP-MS
- Detection arm in which positive ions are extracted from the plasma through sampler and skimmer cones into a quadrupole mass filter that...