Research peptides are often listed with purity figures such as 95, 98 or 99 percent. Those numbers matter, but they only make sense once you know how they are measured and what the remaining percentage contains.

How purity is measured

Purity is usually reported from HPLC as the main peak area divided by the total peak area. It shows how much of the detected material is the target peptide.

What the rest is

The remaining few percent can include truncated sequences, deletion products or residual synthesis reagents. For many assays these are harmless; for sensitive work they can matter.

Choosing a grade

• Screening and pilot work: 95 percent is often acceptable
• Most cell and animal studies: 98 percent or higher is common
• Sensitive analytical work: aim for 99 percent and confirm identity by mass spec

Do not forget identity

High purity does not prove the molecule is correct. Always check the mass spectrometry result alongside HPLC.

A lot-specific COA, like the one supplied with MOTS-c 10mg, should show both measurements. When comparing research peptides from different sources, compare the full COA rather than the headline number.

For laboratory research use only. Not for human consumption.