Purity and Testing
≥99% is printed on every vial. Here is what that number is measuring, how it gets there, and where it stops.
What does the purity figure mean?
Read it as a ratio. Out of everything the instrument picked up in the sample, how much of it was the compound you wanted? At ≥99%, ninety-nine parts in every hundred detected were the compound printed on the label.
How is purity measured?
High-performance liquid chromatography does the work. The sample is pushed through a column, and whatever is in it comes apart according to how tightly each component clings to the column material. They leave at different moments, a detector draws each arrival as a peak, and purity is simply the area under the target peak set against the area under all of them.
What does an HPLC purity result cover?
| Question | Answered by this test |
|---|---|
| Does one component dominate the sample? | Yes |
| What proportion of detected material is it? | Yes |
| Is that component the compound on the label? | No, identity is a separate measurement, typically mass spectrometry |
| Are residual solvents, salts or water present? | No. Assessed separately |
| Which material does it describe? | The batch it was cut from |
Can you confirm identity as well as purity?
Ask and we will. Put the question before you order and we will tell you what is on file for the stock we are shipping now.
Purity and Testing questions
What does ≥99% purity mean?
Run through HPLC, the target compound accounted for at least 99% of all the peak area detected.
Does purity confirm the compound is what the label says?
It does not. All purity tells you is that one component dominates. Proving which component that is takes a separate measurement, usually mass spectrometry.
How is peptide purity measured?
On a high-performance liquid chromatography column. The sample separates, each part shows up as its own peak, and purity is the target peak measured against the total.
Does the figure apply to my vial?
It belongs to whichever batch the certificate was cut for. Send us the batch number off your label and we will match it.