Quality Control & Certificates of Analysis
A research reagent is only as good as its documentation. This guide explains the two tests behind every certificate of analysis — HPLC purity and mass-spectrometry identity — and how to read the document itself.
Last updated September 2, 2026
The two questions QC answers
Quality control on a synthetic peptide answers two separate questions. Identity: is the molecule in the vial the stated sequence? Purity: how much of the material is that molecule versus anything else? Each question has its own instrument.
Mass spectrometry — identity
A mass spectrometer measures the molecular weight of the sample to a fraction of a dalton. Because every sequence has an exact theoretical mass, a measured mass matching the theoretical value confirms the correct sequence was made. A COA reports both numbers side by side — they should agree within the instrument's tolerance.
Analytical HPLC — purity
The purified peptide is run on an analytical HPLC column, and the main-peak area percentage is reported as purity, as described in the purification guide. Research suppliers typically specify ≥98% or ≥99% for catalog peptides.
Reading a COA
A complete certificate of analysis ties the document to a specific batch. Check for:
- Peptide name and sequence, and the lot/batch number matching the vial label.
- Theoretical versus observed mass from mass spectrometry.
- HPLC purity percentage, with the chromatogram attached or available.
- Net content (mg per vial) and appearance.
- Analysis date and the testing laboratory.
NEXTGEN testing
Every NEXTGEN lot is tested by an independent third-party laboratory, and the certificate of analysis for each batch is published on the site. See the Purity / COA section on the home page for current batch documents.
RESEARCH USE ONLY — NOT FOR HUMAN CONSUMPTION. Products are laboratory reagents for in-vitro research by qualified professionals. Sale for human use is strictly prohibited. Nothing in this guide is medical advice or dosing guidance.