What the chromatogram shows
High-performance liquid chromatography separates components as they move through a chromatographic system. The detector response is plotted against retention time. Different components may appear as separate peaks under the selected conditions.
A purity-related result must be read in the context of that method. Separation conditions, detector settings, and how peaks are integrated affect the reported information. Do not assume that two reports used equivalent methods simply because both mention HPLC.
Purity information is not a complete composition claim
An HPLC result describes the detected chromatographic profile. It should not automatically be read as the amount of peptide in a container, total composition by mass, or an inventory of every possible impurity.
Components can behave differently under different conditions. Ask what the method is intended to evaluate and what its reported purity information represents. If identity also matters, discuss adding an MS check rather than drawing identity conclusions from peak appearance alone.
Questions to ask when comparing reports
When a supplier COA and an independent report appear different, start with scope and comparability. Check whether the material, sample reference, and analytical conditions are sufficiently aligned to make the comparison meaningful.
- Which sample was received and identified in each document?
- What testing method and reporting basis were used?
- How were the relevant peaks evaluated?
- Is there enough method context to interpret a difference?
- Would complementary MS information clarify the identity question?
Arrange an HPLC test for your sample
Send the sample name and your testing question before requesting domestic delivery. We will confirm method suitability, required sample quantity, current pricing, and turnaround time. No universal quantity or completion time is promised here.
You receive an English PDF analytical report for the sample received and tested. HPLC findings do not guarantee every unit in the supplier’s batch or prove that a later shipment will be identical. Sampling remains a separate consideration.