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Peptide COA: how to read a peptide lab report
Updated October 21, 2026
A certificate of analysis is only as useful as your ability to check it. Below: what a peptide COA is, how peptide purity is tested, what "lab tested" should mean, and the ten things we look for on any supplier's report, ours included.
For research use only. This guide explains how to read laboratory documents. It is not medical advice and says nothing about using any compound.
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What is a peptide COA?
A peptide COA, or certificate of analysis, is the lab report for one batch of a peptide. A lab takes a sample from the batch, runs its tests and writes up what it found, tied to that batch by its lot number. A useful COA answers three questions with numbers: is it the right compound (identity), how much of the sample is that compound (purity), and how much is in the vial (net content).
How peptide purity is tested
Purity is normally measured by high-performance liquid chromatography (HPLC). The sample is pushed through a column that separates its components, and a detector records each one as a peak. Purity is the target peptide's peak as a percentage of all the peaks. Identity is a separate test: mass spectrometry (MS, or LC-MS when paired with chromatography) measures the molecular mass and compares it with the expected mass. Net content, the amount of peptide actually present, is a third measurement and is the one most often left off.
What "lab tested peptides" should mean
"Lab tested" on its own tells you nothing. It means something when you can see the report for the lot you are buying, the report names that lot and the lab, and it gives identity, purity and net content as numbers. If a seller can't show you the report before you buy, or shows one report for every strength, treat the claim as unproven.
Batch number lookup
The lot number (also called the batch number) is printed on the vial label. Enter it on the seller's lookup page to open the report for that exact batch. Ours is the Torrey Labs lot lookup, with no account needed.
The 10 checks
01
Is there a lot number, and does it match the vial?
Every certificate of analysis should name the batch it tested. Find the lot number printed on the vial or its label and look for the same number on the report. If the report has no lot number, or a different one, it tells you about some other batch, not the one in your hands.
A report only speaks for the batch it tested.
02
Does the tested amount match the strength on the label?
Reports usually state how much material was found in the sample (often called net content or quantity). That figure should line up with the strength on the label. A report run on a 10 mg sample says nothing reliable about a 20 mg or 60 mg vial, even from the same supplier.
A report on a 10 mg sample does not verify a 20 mg vial.
03
Is identity confirmed by mass spectrometry?
High-performance liquid chromatography (HPLC) separates a sample and measures how much of it is one substance. It does not, by itself, prove which substance that is. Mass spectrometry (MS or LC-MS) measures molecular mass and is the standard way to confirm identity. Look for an observed mass that matches the expected one.
HPLC alone shows purity, not what the compound is.
04
Is purity reported as a number from HPLC?
Purity should be a number, usually a percentage from HPLC peak area, with the chromatogram or method named. Words like “pharmaceutical grade” or “high purity” without a figure are claims, not results.
“High purity” with no figure is marketing, not a result.
05
Is the lab named, with contact details you can check?
The report should name the laboratory that ran the test, with an address, phone number or website you can check yourself. A report with no lab named at all, or a lab you can't find anywhere, gives you no one to ask about the result.
A lab you can find is a lab you can ask about the result.
06
Is the lab accredited (for example ISO/IEC 17025)?
ISO/IEC 17025 is the international standard for testing laboratories. An accredited lab has had its methods and quality system audited by an outside body. Not every good lab holds it, but it is the strongest simple signal you can check.
Accreditation means its methods are audited.
07
Is the report dated, and recent enough to be current stock?
Look for the date the sample was received and the date it was tested or reported. A report from long ago may describe a batch that is no longer being sold.
An old report may describe a batch that sold out long ago.
08
Does the lab offer a way to verify the report?
Some labs give each report a verification code, a QR code or an online portal where you can pull up the original. That rules out an edited PDF. If there is no verification route, you can still email the lab and ask them to confirm the report number.
A verification code or portal rules out an edited PDF.
09
Were contaminants tested (endotoxin, heavy metals, sterility)?
Identity and purity are the basics. Tests for bacterial endotoxin, sterility and heavy metals are separate and cost extra, so many reports leave them out. If they are not on the report, they were not tested, which is different from the product being free of them.
Many reports skip them. Missing is not the same as clean.
10
Is the same report reused across lots or strengths?
The most common warning sign is one document attached to many products: the same report on several strengths, several lots, or a new batch months later. Each lot and strength should have a report that names it.
One document on many products is the most common red flag.
Common questions
What is a peptide COA?
A peptide COA (certificate of analysis) is the lab report for one batch of a peptide. It names the batch by lot number and gives the test results for a sample from it: usually identity by mass spectrometry, purity by HPLC and the measured amount, or net content.
How is peptide purity tested?
Peptide purity is usually measured by high-performance liquid chromatography (HPLC): the sample is separated and the target peptide's share of the total signal is reported as a percentage. Identity is confirmed separately by mass spectrometry (often LC-MS), which checks the molecular mass.
What should "lab tested peptides" mean?
At minimum: a named lab tested a sample from the same lot you are buying, the report shows that lot number, and it gives identity, purity and net content as numbers. A seller should let you look the report up by lot number before you buy.
How do I look up a batch number?
Find the lot (batch) number printed on the vial label or cap, then enter it on the seller's lot lookup page. On Torrey Labs that is torreylabs.store/certificates, which opens the report for that exact lot with no account needed.
What is a certificate of analysis (COA)?
A certificate of analysis is a report from a testing laboratory describing what it found in a sample: usually the compound's identity, its purity and the amount present, tied to a specific batch by its lot number.
What is the difference between HPLC and mass spectrometry?
HPLC separates a sample and measures how much of it is one substance, which gives a purity figure. Mass spectrometry measures molecular mass, which confirms what the substance is. A complete report uses both.
Does a high purity number mean the vial holds the labeled amount?
No. Purity describes how much of the sample is the target compound. The amount present is a separate measurement, often called net content or quantity, and it should match the strength on the label.
Can one lab report cover several products or strengths?
Not reliably. A report describes the sample that was tested. Each lot and each strength should have a report that names it.
Try it on a real report
Every Torrey Labs report is looked up by lot number, with no account needed. Run the ten checks on ours.
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