How to Verify a Certificate of Analysis (COA)
A valid Certificate of Analysis (COA) must come from an independent, accredited third-party lab, show 98%+ purity via HPLC and mass spectrometry, and have batch numbers and dates that match the product you received.
Overview
A Certificate of Analysis (COA) is a laboratory document that verifies what is actually inside a vial of peptide. When buying research peptides — which are not regulated like pharmaceuticals — a third-party COA is your primary safeguard against mislabeled, contaminated, or impure product. This guide walks you through, step by step, how to read a COA and what to look for.
What a COA Should Content
A legitimate COA includes:
- **Lab identity and accreditation** (e.g., ISO 17025)
- **Product name and peptide sequence**
- **Batch/lot number**
- **Date of testing**
- **Testing methods used** (HPLC, mass spectrometry)
- **Purity percentage**
- **Identity confirmation**
- **Heavy metals / endotoxin screening** (for higher-grade products)
- **Signature of the analyst**
Step-by-Step Verification
### Step 1: Confirm the Lab Is Independent and Accredited
The most common fraud is a vendor providing a COA from its own in-house lab — which has an incentive to report favorable results. The lab should be:
- **Independent (third-party):** No financial or corporate relationship with the vendor.
- **Accredited:** Look for ISO 17025 accreditation, the international standard for testing and calibration laboratories. Accreditation means the lab's methods and quality systems have been audited by an independent body.
Trusted third-party labs in the peptide space include Janoshik Analytical, Finnrick Scientific, Freedom Diagnostics, and other ISO 17025-accredited facilities.
### Step 2: Check Purity Percentage
Purity is the headline number — the fraction of the sample that is the stated peptide versus impurities.
- **≥98%** is the minimum acceptable for research-grade peptides.
- **≥99%** is preferred, especially for injectable or long-term use.
- **Below 98%** suggests manufacturing or purification problems; reject the batch.
The purity value should be derived from HPLC (high-performance liquid chromatography) and reported as peak area percent.
### Step 3: Confirm Identity via Mass Spectrometry
Purity alone does not confirm that the substance is the correct peptide. **Mass spectrometry (MS)** measures the molecular weight of the sample and compares it to the expected mass.
- Look for an MS spectrum with a single dominant peak at the expected molecular weight.
- A match confirms molecular identity.
- If only HPLC is reported with no MS data, you have purity but not identity — insufficient.
### Step 4: Review HPLC Data
HPLC separates the sample's components and quantifies each.
- A **single sharp peak** at the expected retention time indicates high purity.
- **Multiple peaks or a broad tail** indicate impurities or degradation products.
- The purity percentage should be computed from the main peak's area relative to the total.
### Step 5: Match Batch Numbers
The batch or lot number on the COA must exactly match the number printed on the vial label you received. Vendors that provide a generic COA without a batch match are either careless or concealing something. A mismatch means the COA does not apply to your product.
### Step 6: Check the Testing Date
COAs should be recent — typically within the last 6-12 months. Older COAs may not reflect the current batch's quality. If a vendor cannot produce a recent COA for the batch you received, consider it a red flag.
### Step 7: Examine Expiration / Retest Date
Quality COAs often include an expiration or retest date for the batch. Peptides degrade over time; a batch near or past its retest date may have reduced potency.
Red Flags
- **COA from the vendor's own lab** (no independence).
- **No accreditation claim** (no ISO 17025 or equivalent).
- **Purity below 98%** without explanation.
- **HPLC only, no mass spectrometry** (identity not confirmed).
- **Batch number missing or mismatched** to the vial.
- **Date more than 12 months old**, or undated.
- **Vague language** like "tested for purity" with no actual data.
Putting It All Together
A valid COA should let you answer yes to all of these:
1. Is the lab independent and ISO 17025-accredited?
2. Is purity ≥98% (preferably ≥99%)?
3. Is identity confirmed by mass spectrometry?
4. Does the batch number match the vial?
5. Is the test date recent (within 6-12 months)?
If any answer is no, the product is not adequately verified. When in doubt, request a fresh COA from the vendor; reputable sellers will provide one promptly. For full context on safe handling, see our *Peptide Safety Guide*.
Frequently Asked Questions
What purity percentage should I look for on a COA?
Minimum 98% for research-grade peptides; 99% or higher is preferred, especially for injectable use. Below 98% indicates manufacturing or purification problems.
How do I know the COA lab is independent?
The lab should be third-party (not the vendor's own), and ideally ISO 17025-accredited. Trusted labs include Janoshik Analytical, Finnrick Scientific, and Freedom Diagnostics.
Why is mass spectrometry important on a COA?
HPLC confirms purity but not identity. Mass spectrometry confirms the molecular weight matches the expected peptide, verifying that the vial contains the correct substance.
What should I do if the batch number on the COA doesn't match the vial?
Do not use the product. A mismatch means the COA does not apply to your vial. Contact the vendor for a correct COA or return the product.
How recent should a COA be?
Within 6-12 months. Older COAs may not reflect the current batch quality. An undated or very old COA is a red flag.
References
- ISO/IEC 17025:2017 General Requirements for the Competence of Testing and Calibration Laboratories.
- USP General Chapter <1058> Analytical Instrument Qualification.
- Pharmacopeial Forum: Peptide Impurity Analysis by HPLC and MS.
- Janoshik Analytical; Finnrick Scientific; Freedom Diagnostics — COA reporting standards.