Updated 2026-09 · 4 min read
“99% pure” is the headline figure on most research peptide listings. It is a real, measurable quantity — but only as good as the method that produced it, and the number alone hides more than it shows.
What HPLC measures
High-performance liquid chromatography separates a sample into its components by pushing it through a column; each component emerges at a characteristic time and registers as a peak. Purity is the area of the main peak as a percentage of all peak area. A 99% figure means the target sequence accounts for 99% of what the detector saw.
Why the method matters
Two 99% figures are not necessarily comparable. Detector wavelength, gradient, and column all affect what is resolved and what is missed, so a purity figure is only meaningful with the method stated. This is why a COA reports the method beside the number, and why identity confirmation by mass spectrometry sits alongside it — purity grades the sample, identity proves it is the right one.
A reasonable standard
For research peptides, a purity specification of 98% or better by HPLC, with identity confirmed by LC-MS and both published per lot, is a defensible baseline. The specification matters less than whether it is measured, stated with its method, and published for the exact lot you receive.
This material is synthesized from publicly available preclinical literature and industry documentation for qualified laboratory researchers. It is not medical, veterinary, therapeutic, or diagnostic advice. All compounds are supplied and discussed solely for in-vitro laboratory research and are not for human or animal use.