Quality guide
What peptide purity means for research
Short answer: peptide purity is the share of a sample that is the intended peptide rather than something else. A 99% result means almost all of the sample is the target peptide; an 80% result means about one fifth of it is other material, which can change how an experiment behaves.
What does a peptide purity percentage measure?
A purity percentage compares the amount of the intended peptide with everything else the test can detect in the same sample.
The "everything else" is usually leftovers from making the peptide: shorter chains, chains missing one building block, or other by-products of synthesis.
What is the difference between 99% and 80% purity?
At 99%, about 1 part in 100 is something other than the target peptide. At 80%, about 20 parts in 100 are something else.
That gap matters in research. If a fifth of the powder is other material, the real amount of peptide in a measured sample is lower than expected, and the extra material may have effects of its own. Results become harder to repeat and compare.
How does HPLC work, in general terms?
HPLC stands for high-performance liquid chromatography. It is a common lab method for separating the parts of a mixture.
A small dissolved sample is pushed under pressure through a packed column. Different molecules travel through the column at different speeds, so they come out at different times. A detector records each one as a peak on a chart called a chromatogram.
In general, purity by this kind of method is worked out by comparing the size of the main peak with the total size of all peaks. A larger main peak relative to the rest means a purer sample.
What does mass spectrometry add, in general?
Separation shows how much of a sample is one thing. It does not by itself prove what that thing is. Mass spectrometry, in general, measures the mass of molecules, which can help confirm that the main material has the mass expected for the intended peptide.
This page explains these methods as general background. For what was reported on a specific Veridian batch, read that batch's Certificate of Analysis.
How do I check the purity of a Veridian product?
Every Veridian product has a COA per batch from third-party testing. Find the batch code on your vial label and enter it on the COA lookup page. Our guide on how to read a COA walks through each line.
Does the powder form affect purity?
All Veridian products are supplied as lyophilized (freeze-dried) powder in a sealed vial. Freeze-drying removes water, and dry peptides are generally more stable than peptides kept in liquid.
Peptide purity questions
Is a higher purity percentage always better?
For most research, yes. A higher percentage means less unknown material in the sample, which makes results easier to repeat.
Can two labs report different purity for the same sample?
Yes. Results can vary with the method, equipment and settings used. That is why a COA should name the batch it describes.
Where do I see the purity for my vial?
On the Certificate of Analysis for your batch. Enter the batch code from your label on the COA lookup page.
Related guides: third-party testing, how to read a COA and shipping speed. Ready to order? Shop peptides.