HPLC and LC-MS

Purity is a chromatogram. Identity is a mass. They are not interchangeable.

HPLC-UV reports the area of the main peak at a stated wavelength. It does not prove the peak is the substance on the label. ESI-MS or LC-MS does that.

We will not ship a lot whose observed mass is outside the window on the SKU page. GHK-Cu acetate, TB-500 17–23 (~889 Da) and full thymosin β4 (~4963 Da) are different files.

Ask the desk or open /verify with the lot. Do not trust a badge that says 99% without a method.