Verify a Certificate of Analysis (COA) in 7 Steps

A valid Certificate of Analysis (COA) should come from an outside lab. It should show 98%+ purity by HPLC and mass spec. It should also list batch numbers and dates that match the vial you got.

Overview

A Certificate of Analysis (COA) is a lab report that shows what is really in a peptide vial. If you buy research peptides, a third-party peptide certificate of analysis is your main check against bad labels, dirt, or weak product. This guide shows how to read a COA step by step.

What a COA Should Include

A real COA includes:

• Lab name and ISO 17025 cert
• Product name and peptide sequence
• Batch/lot number
• Test date
• Test methods used (HPLC, mass spec)
• Purity percent
• Identity check
• Heavy metal / endotoxin test (for higher-grade products)
• Analyst signature

Step-by-Step Check

Step 1: Make Sure the Lab Is Outside and Certified

The most common fraud is a vendor using its own lab, which has a reason to give a good result. The lab should be:

• Outside lab: No money or company link to the vendor.
• Certified: Look for ISO 17025 cert, the global standard for test labs. It means the lab's methods and quality system were checked by an outside group.

Trusted labs in the peptide field include Janoshik Analytical, Finnrick Scientific, Freedom Diagnostics, and other ISO 17025 labs.

Step 2: Check the Purity Percent

Purity is the main number. It shows how much of the sample is the named peptide, not other material.

• 98%+ is the least you should accept for research-grade peptides.
• 99%+ is better, especially for injectables or long-term use.
• Below 98% points to manufacturing or cleaning problems. Reject the batch.

The purity number should come from HPLC and be listed as peak area percent.

Step 3: Confirm Identity with Mass Spec

Purity alone does not prove the sample is the right peptide. Mass spec (mass spectrometry) checks the sample's weight and compares it with the expected mass.

• Look for an MS trace with one main peak at the expected weight.
• A match confirms the peptide's identity.
• If the report shows only HPLC and no MS data, you have purity but not identity. That is not enough.

Step 4: Review the HPLC Data

HPLC separates the sample's parts and measures each one.

• A single sharp peak at the expected time points to high purity.
• Many peaks or a wide tail point to impurities or breakdown products.
• The purity percent should come from the main peak's area compared with the total.

Step 5: Match the Batch Number

The batch or lot number on the COA must match the number on the vial you got. If the vendor gives a generic COA with no batch match, that is careless at best and hiding something at worst. A mismatch means the COA does not apply to your product.

Step 6: Check the Test Date

COAs should be recent, usually from the last 6-12 months. Older COAs may not fit the batch you have now. If the vendor cannot give you a fresh COA for your batch, treat that as a warning sign.

Step 7: Check the Expiry or Retest Date

Good COAs often list an expiry or retest date for the batch. Peptides can break down over time, so a batch near or past its retest date may be less strong.

Red Flags

• COA from the vendor's own lab — no outside check.
• No cert claim — no ISO 17025 or similar.
• Purity below 98% with no clear reason.
• HPLC only, no mass spec — identity not proven.
• Batch number missing or mismatched with the vial.
• Date older than 12 months or no date at all.
• Vague wording like general purity claims with no real data.

Putting It All Together

A valid COA should let you answer yes to all of these:

1. Is the lab outside and ISO 17025 certified?

2. Is purity 98% or higher, and ideally 99% or higher?

3. Is identity confirmed by mass spec?

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 well checked. When in doubt, ask the vendor for a fresh COA. Good sellers will send one fast. For more on safe handling, see our Peptide Safety Guide.

Frequently Asked Questions

What purity percent should I look for on a COA?

At least 98% for research-grade peptides. 99% or higher is better, especially for injectables. Below 98% points to manufacturing or cleaning problems.

How do I know the COA lab is outside?

The lab should be third-party, not linked to the vendor, and ideally ISO 17025 certified. Trusted labs include Janoshik Analytical, Finnrick Scientific, and Freedom Diagnostics.

Why is mass spec important on a COA?

HPLC shows purity, but not identity. Mass spec shows the molecular weight matches the expected peptide, which helps prove the vial has the right substance.

What should I do if the batch number on the COA does not match the vial?

Do not use the product. A mismatch means the COA does not apply to your vial. Ask the vendor for the right COA or return the product.

How recent should a COA be?

Within 6-12 months. Older COAs may not fit the current batch. A very old or undated COA is a red flag.

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