A Certificate of Analysis (COA) is a document issued by a testing laboratory that reports the quality, purity, and identity of a specific batch of peptide. It's the single most important document for evaluating whether a peptide is suitable for research. Here's how to read one.
Without a COA, you're trusting a supplier's word that the peptide is what they say it is. A legitimate COA from an independent laboratory provides objective, quantitative evidence of:
Red flag: If a supplier cannot provide a COA for a specific batch, or only provides a "generic" COA without batch-specific data, this is a significant quality concern. Every batch should be independently tested.
The top of a COA lists the basic product information:
High-Performance Liquid Chromatography (HPLC) is the gold standard for peptide purity testing. It separates the sample into its component molecules and measures what percentage is the target peptide vs. impurities.
Tip: If the COA includes the actual HPLC chromatogram image, look for a single dominant peak with a clean baseline. Multiple large peaks or a noisy baseline indicate significant impurities or degradation.
Mass spectrometry confirms the identity of the peptide by measuring its molecular weight. This is your assurance that the compound is actually what it claims to be.
This describes the physical form of the peptide. Research-grade lyophilised peptides should appear as a white to off-white powder or fluffy cake. Discoloration (yellow, brown) can indicate degradation or impurities.
Reports whether the peptide dissolves properly in standard solvents (usually water, bacteriostatic water, or DMSO). A peptide that won't dissolve may be degraded or incorrectly formulated.
This is a frequently overlooked but critical measurement. A vial labelled "5 mg" may contain 5 mg of total powder, but the actual peptide content might be less due to:
Net peptide content is expressed as a percentage (typically 70-85%) and tells you the actual active peptide mass. A 5 mg vial with 80% net peptide content contains 4 mg of actual peptide.
Endotoxins are bacterial cell wall fragments that can cause inflammatory responses. The Limulus Amebocyte Lysate (LAL) test detects and quantifies endotoxin contamination.
Peptide synthesis uses organic solvents (DMF, DCM, acetonitrile, TFA) that must be removed during purification. A residual solvents test confirms these are within safe limits, typically using gas chromatography (GC).
There's an important distinction between COAs generated by the manufacturer vs. an independent third-party lab:
New-U standard: All New-U Peptides products are independently verified by both Janoshik Analytical and Freedom Diagnostics - two of the most respected independent peptide testing laboratories in the world.
When reviewing a peptide COA, verify:
Once you have verified your COA, the next steps are reconstituting the peptide, confirming draw volumes with the reconstitution calculator, and following correct storage practices to maintain potency.
What is a COA for peptides?
A Certificate of Analysis is a document issued by a testing laboratory that reports the quality, purity, and identity of a specific batch of peptide. It provides objective evidence that the peptide is the correct compound and meets quality standards.
What HPLC purity should a research peptide have?
Research-grade peptides should have HPLC purity of 98% or higher. Premium peptides target 99%+. A single dominant peak on the chromatogram with a clean baseline indicates high purity.
Why is third-party COA testing important?
In-house COAs are produced by the manufacturer, creating a conflict of interest. Third-party COAs from independent labs like Janoshik Analytical or Freedom Diagnostics provide unbiased verification - the gold standard.
Every New-U Peptides product includes dual third-party verification from Janoshik and Freedom Diagnostics.
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