How to Read a Peptide COA | What Is a Certificate of Analysis?
QSC · BUYER GUIDE
How to Read a Peptide Certificate of Analysis (COA) HPLC · Mass Spectrometry · Janoshik · What to Look For · Independent vs In-House COA
A Certificate of Analysis (COA) is the primary quality document for a research peptide batch. It contains HPLC purity percentage, mass spectrometry molecular weight confirmation, batch number, and testing date. Understanding what makes a COA trustworthy — and the critical difference between independent and in-house COAs — is essential for evaluating any peptide supplier.
A COA is a quality document confirming a peptide’s purity and identity. It should include: HPLC purity percentage (research grade: ≥99%), mass spectrometry result confirming correct molecular weight, batch/lot number, compound name, and testing laboratory. A COA from an independent laboratory is more trustworthy than one issued by the supplier’s own lab.
What is HPLC and what purity should research peptides have?
HPLC (High-Performance Liquid Chromatography) separates a peptide sample’s components and measures the percentage of the target compound vs impurities. Research-grade peptides should show ≥99% HPLC purity. Anything below 98% is generally not considered research grade. QSC peptides are verified at ≥99% HPLC on every batch.
What is mass spectrometry (MS) in a peptide COA?
Mass spectrometry (MS) confirms the molecular weight of the compound matches the theoretical molecular weight of the target peptide. While HPLC tells you purity percentage, MS confirms you have the correct compound. Both are needed: HPLC proves purity, MS proves identity. QSC COAs include both HPLC and MS on every batch.
What is an independent COA vs an in-house COA?
An independent COA is issued by a third-party analytical laboratory not affiliated with the supplier — such as Janoshik, whose results are published at verify.janoshik.com. Anyone can verify the result using only the batch code. An in-house COA is issued by the supplier’s own lab: self-generated, not verifiable by third parties, and potentially alterable. Independent COAs are the gold standard. QSC uses Janoshik exclusively.
How do I verify a QSC Janoshik COA?
Every QSC order includes the Janoshik batch code. Visit verify.janoshik.com, enter the batch code, and the independent lab result appears — showing HPLC purity and MS confirmation for that specific batch. This process does not require any trust in QSC: you verify directly with the testing laboratory.
Research Use Only: All QSC products sold strictly for in vitro laboratory research. Not for human or veterinary use. Information on this page is educational only and does not constitute medical advice.
