Deuterated Internal Standard
Definition
An isotopologue of the analyte where two to five hydrogens are replaced by deuterium. Same chromatographic and ionisation behaviour, slightly higher mass. Co-eluted, co-extracted and co-injected with the analyte to correct for matrix effects, ion suppression and injection variability.
- Field
- Tandem mass spectrometry (MS/MS)
- Structure
- Analyte isotopologue with 2 to 5 hydrogens replaced by deuterium
- Behaviour
- Same chromatography and ionisation, slightly higher mass
- Purpose
- Corrects for matrix effects, ion suppression, injection variability
Common questions
Why does a deuterated version of the analyte make a better internal standard than an unrelated compound?+
Because it co-elutes and ionises the same way as the target analyte, it experiences essentially the same matrix suppression and extraction losses during the run, so any variation in its signal reflects instrument and sample-prep effects rather than a chemical difference, letting the analyte's response be corrected against it directly.
What happens to quantitation accuracy if no deuterated standard is available for a given analyte?+
Labs typically substitute a structurally similar deuterated compound or a non-deuterated internal standard with close chromatographic behaviour, but the correction is less precise, since a poorly matched standard can behave differently under ion suppression than the true analyte does.
Related terms
- Accurate Mass and Mass Defect
- On a Q-TOF or Orbitrap, the measured m/z is reported to four decimal places at parts-per-million accuracy. The deviation from the nominal...
- CID and HCD
- Collision-induced dissociation. The precursor is accelerated and collides with a neutral gas (nitrogen, argon, helium) in the collision cell. Internal energy converts...
- MRM (Multiple Reaction Monitoring)
- A targeted MS/MS scan mode on a triple quadrupole that monitors specific precursor-to-product ion transitions, with two transitions per analyte (quantifier and...
- Quantifier and Qualifier Transitions
- The most intense MRM transition is the quantifier and is used for the concentration calculation. The second (and sometimes third) transition is...
- Tandem MS (MS/MS)
- Two stages of mass selection in series with a fragmentation step in between. The first stage selects a precursor ion, a collision...