---
title: "Counter-ion: research glossary | Sable Peptides"
description: "A counter-ion is an ion that accompanies a charged molecule to maintain overall electrical neutrality. Synthetic peptides with basic residues carry positiv"
canonical: https://www.sablepeptides.co.uk/glossary/counter-ion
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

Glossary

# Counter-ion

A counter-ion is an ion that accompanies a charged molecule to maintain overall electrical neutrality. Synthetic peptides with basic residues carry positive charges balanced by anions such as trifluoroacetate, acetate or chloride. Counter-ions contribute to the weighed mass of a lyophilised peptide, which is one reason net peptide content is usually below 100%.

Source: [en.wikipedia.org](https://en.wikipedia.org/wiki/Counterion)

## Related terms

-   [Peptide](/glossary/peptide)
-   [Net peptide content](/glossary/net-peptide-content)

[Back to glossary A–Z](/glossary/terms)

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