Adduct Formation in Peptide Mass Spectrometry

Adducts form when a peptide ion associates with another species such as sodium, potassium, solvent, or mobile-phase components.

Common sources

• salts
• buffers
• glassware
• solvents
• detergents
• counterions
• sample containers

Spectral effects

Adducts create additional peaks or broaden isotope envelopes. They can complicate deconvolution and create apparent mass heterogeneity.

Control

Potential controls include:

• desalting
• volatile buffers
• clean solvents
• controlled sample preparation
• low-salt containers
• optimized source conditions

Interpretation

An observed mass shift should not automatically be assigned to a covalent modification. Adduct chemistry must be considered.

Frequently asked questions

Are sodium adducts covalent?

Usually not.

Can adducts survive LC separation?

Yes, depending on conditions.

Does more source voltage remove all adducts?

No. It may also fragment or alter the analyte.

Can counterions create adduct signals?

Yes.

Key takeaways

Adducts are common, method-dependent spectral features. Correct interpretation prevents them from being mistaken for true peptide modifications.

References

1. Aebersold R, Mann M. Mass-spectrometric exploration of proteome structure and function. Nature. 2016.
2. Gross JH. Mass Spectrometry: A Textbook. Springer.

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TSMS Labs educational disclaimer: For laboratory research and educational purposes only. Not for human consumption. This content is not medical, clinical, or regulatory advice.