Reading a Janoshik COA
How to interpret High-Performance Liquid Chromatography (HPLC) graphs and mass spectrometry data to verify purity claims.
What is a COA?
TL;DR: The HPLC section of a peptide CoA shows a chromatogram — a graph of UV absorbance over time. The main peak represents your target peptide, and its area relative to all peaks gives the purity percentage. Learn to evaluate retention times, peak shapes, and baseline quality to distinguish reliable from questionable analytical data.
Last verified: March 2026 | Data accuracy confirmed by ChemVerify Editorial Team
A Certificate of Analysis (COA) is a document issued by an analytical laboratory confirming the identity and purity of a chemical compound.
HPLC Fundamentals
High-Performance Liquid Chromatography separates compounds based on their chemical properties, producing a chromatogram that shows retention time and peak area.
Interpreting Chromatogram Peaks
The main peak represents your target compound. Purity is calculated as the percentage of the main peak area relative to total peak area.
A purity of ≥98% is generally considered acceptable for research-grade peptides. Premium suppliers typically achieve ≥99%.
Mass Spectrometry Confirmation
Mass spectrometry confirms molecular identity by measuring the mass-to-charge ratio. The observed mass should match the theoretical molecular weight.
Frequently Asked Questions
What does a good HPLC chromatogram look like?
A quality chromatogram shows a sharp, symmetrical main peak with a stable baseline and minimal additional peaks. The main peak should be well-resolved from any impurity peaks. A flat baseline before and after the gradient indicates proper instrument calibration and clean column conditions.
What does retention time tell me?
Retention time is the elapsed time from sample injection to peak detection. It reflects the peptide's hydrophobicity — more hydrophobic peptides elute later. While retention time alone does not identify a peptide, a major shift from expected values can indicate a different compound or degradation.
Why do some CoAs show multiple HPLC peaks?
Additional peaks represent impurities — typically deletion sequences (missing one or more amino acids), oxidized variants, or truncated synthesis products. Small impurity peaks are normal; the key metric is the relative area of the main peak (your purity percentage).
Can HPLC conditions affect the reported purity?
Yes. Different column types, gradient profiles, and detection wavelengths can yield different purity values for the same sample. This is why a comprehensive CoA should report the analytical conditions used, allowing comparison with standardized methods and enabling reproducibility.
Compounds Referenced in This Article
Explore detailed chemical profiles and research guides for compounds discussed in this article:
- BPC-157: Complete Research Guide → /learn/bpc-157
- Semaglutide: Complete Research Guide → /learn/semaglutide
Further Reading on ChemVerify
- Read more: AI-Guided High-Throughput Screening Accelerates Antimicrobial Peptide-Mimicking Polymer Discovery → https://www.chemverify.com/learn/ai-guided-antimicrobial-peptide-polymer-discovery
- Read more: Re-Engineering Insulin for Oral Delivery: Structural Modifications and Formulation Advances → https://www.chemverify.com/learn/insulin-oral-delivery-peptide-engineering
- Read more: Cyclic Lipopeptides: Biosurfactant Peptides as Next-Generation Drug Delivery Modulators → https://www.chemverify.com/learn/cyclic-lipopeptides-drug-delivery-modulators
- Read more: Microneedle-Delivered Peptide Decoy Receptors Show Promise in Psoriasis Treatment → https://www.chemverify.com/learn/microneedle-peptide-decoy-receptors-psoriasis
- Read more: GLP-1 Receptor Agonists Demonstrate Cardiorenal Protection in Chronic Kidney Disease: Meta-Analysis → https://www.chemverify.com/learn/glp1-receptor-agonists-cardiorenal-protection-ckd
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