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High Performance Liquid Chromatography is the standard method for measuring the purity of synthetic peptides. What the method measures, how it works, and what the results in the CoA mean.
HPLC stands for High Performance Liquid Chromatography. It is an analytical separation method in which a liquid sample mixture is pumped through a separation column under high pressure. The various components of the sample migrate through the column at different speeds and are thus separated from each other.
In the context of research peptides, HPLC-UV is used — this means the separated components are measured via UV detection. Peptides absorb UV light at a wavelength of typically 214 nm or 220 nm, which enables precise quantitative determination.
The sample is dissolved in a solvent and injected into the HPLC system. A pump drives the solvent mixture (the "mobile phase") under pressure through the separation column (the "stationary phase"). Different molecules interact with the stationary phase to varying degrees — as a result, they exit the column at different times.
The detector continuously measures the UV absorbance of the eluate exiting the column. The result is a chromatogram — a graphical representation of absorbance over time. Each peak in the chromatogram corresponds to a compound in the sample.
Important
The purity value in the CoA is derived from the ratio of the peak area of the target compound to the total peak area of all peaks in the chromatogram. A value of 98% means: 98% of the detected amount of substance is accounted for by the desired peptide.
HPLC-UV measures purity — i.e., the relative proportion of the target compound. Mass spectrometry (MS) complements this through identity confirmation: it measures the molecular weight of the compound, thereby confirming that it is indeed the desired peptide.
A complete CoA for research peptides ideally includes both methods — HPLC-UV for the purity value and MS for sequence and identity confirmation.
An HPLC purity value of ≥98% is the recognized standard for research-grade peptides. It means that at least 98% of the measured substance is accounted for by the target peptide. The remaining ≤2% may consist of synthesis by-products, reagent residues, or other impurities.
For most preclinical research applications in cell culture and animal models, ≥98% is considered sufficient for reproducible results. For highly sensitive assays, higher purity may be required.
Note
This article is for scientific information purposes only. It does not constitute medical advice. All mentioned products are intended exclusively for research purposes in authorized laboratory environments.