CID and HCD
Definition
Collision-induced dissociation. The precursor is accelerated and collides with a neutral gas (nitrogen, argon, helium) in the collision cell. Internal energy converts to bond-cleavage. Higher-energy collisional dissociation (HCD) on Orbitrap instruments uses a dedicated cell at higher energy and gives more reproducible fragmentation than ion-trap CID.
- CID mechanism
- Precursor ion collides with neutral gas, converting kinetic to internal energy
- Common collision gases
- Nitrogen, argon, helium
- HCD platform
- Dedicated higher-energy cell on Orbitrap instruments
- HCD advantage
- More reproducible fragmentation than ion-trap CID
Common questions
Why does HCD give more reproducible spectra than trap-based CID?+
HCD uses a dedicated collision cell with a fixed, higher collision energy applied outside the ion trap, avoiding the low-mass cutoff and energy-dependent trapping effects that make ion-trap CID spectra vary more between instruments and runs.
What is the low-mass cutoff problem in ion-trap CID?+
Ion traps cannot stably retain fragment ions much below about a third of the precursor's mass during fragmentation, so small diagnostic fragments can be lost, which HCD's beam-type collision cell does not suffer from.
Which is preferred for forensic drug or toxin identification?+
HCD is generally favoured on Orbitrap systems for library-searchable, reproducible fragment spectra, while CID remains widely used on other platforms and for certain fragmentation behaviours HCD does not reproduce as cleanly, such as some neutral losses.
Related terms
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- MRM (Multiple Reaction Monitoring)
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- Quantifier and Qualifier Transitions
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- Tandem MS (MS/MS)
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