A Certificate of Analysis is the single most important document a research peptide vendor can give you. It's also the document that almost no one teaches researchers how to actually read. This guide walks through every section of a typical COA, what each number means, and the warning signs of a fake or misleading certificate.
What a COA is supposed to do
A Certificate of Analysis is a lab-issued document that reports the results of identity and purity testing on a specific batch of material. The key word is batch. A COA is not a generic statement about a product — it's a snapshot of one specific production run. If you order three vials and they're from three different batches, you should be able to download three different COAs.
The COA's job is to answer two questions:
- Is this what the label says it is? (Identity)
- How much of it is the real thing versus impurities? (Purity)
Everything else on the document supports those two answers.
The header information
The top of any legitimate COA will list:
- Product name — the compound being tested
- Lot number / batch number — the unique identifier for this production run
- Sample appearance — usually "white lyophilized powder" or similar
- Date received — when the lab got the sample
- Date reported — when the lab finalized the results
- Lab accession number — the lab's internal reference
The lot number is critical. It must match the lot number printed on your vial. If you receive a vial with lot BPC240801 but the COA says BPC240615, something is wrong — either you got the wrong document or the wrong vial. Never accept a "we'll send the right COA later" answer; the document should be ready before the product ever ships.
Identity confirmation: the mass spectrum
Identity testing answers the question "is this molecule actually what we claim it is?" The standard method is liquid chromatography coupled with mass spectrometry, often abbreviated LC-MS.
The mass spectrum on your COA shows a graph with mass-to-charge ratio (m/z) on the X-axis and intensity (or relative abundance) on the Y-axis. You'll see one or more tall peaks at specific m/z values. For peptide identification, the lab is looking for peaks that match the theoretical exact mass of the target compound, typically reported in three forms:
- The molecular ion
[M+H]+(the molecule plus one proton) - The doubly-charged ion
[M+2H]2+(common for larger peptides) - The deprotonated form
[M-H]-(in negative mode)
If the observed mass matches the theoretical mass within about 5 parts per million, identity is confirmed. If the mass doesn't match — even by a small amount — the compound in the vial isn't what the label claims.
What you should look for: the COA should explicitly state both the theoretical mass and the observed mass, with the difference (delta) shown. Saying "identity confirmed" without showing the actual masses is a red flag.
Purity quantification: the HPLC chromatogram
Purity testing tells you how much of the sample is the target compound versus impurities, degradation byproducts, residual solvents, or unreacted starting materials.
The standard method is High-Performance Liquid Chromatography with UV detection (HPLC-UV). The chromatogram looks like a baseline with one large peak and (ideally) very small peaks elsewhere.
Here's how to read it:
- The X-axis is retention time — how long it took for each component of the sample to elute (come out the other end of the separation column).
- The Y-axis is absorbance — how much UV light each component absorbed as it passed the detector.
- The big peak at some retention time is your target compound.
- Small peaks at other retention times are impurities.
The purity percentage is calculated by dividing the area under the target peak by the total integrated area of all detected peaks. So a purity of 99.5% means 99.5% of the absorbance signal came from the target compound, and 0.5% came from impurities.
What you should look for: a real chromatogram has visual character — a slightly noisy baseline, peaks that aren't perfectly symmetrical, possibly a small solvent peak right at the start. A "chromatogram" that's a perfect triangle on a perfectly flat line is a graphic, not real data.
What "purity" doesn't mean
A purity number is a relative measurement. It tells you "of the stuff that absorbed UV light at the detection wavelength, this much was the target compound." It does not directly tell you:
- The absolute quantity of compound in the vial (that's net content — see below)
- Whether the compound is biologically active
- Whether the compound has degraded since manufacturing
- The presence of UV-transparent impurities like salts or moisture
This is why a COA is necessary but not sufficient. A 99.9% purity result on a vial that's been sitting in a hot warehouse for two years tells you the original synthesis was good, not that the product is currently usable.
Net content
Many COAs also report net content — the actual mass of compound in the vial, typically measured against the labeled dosage. A vial labeled "10mg" should contain at least 10mg of target compound. Most quality manufacturers slightly over-fill to ensure full dose after subtracting residual moisture.
If your COA reports 9.2mg net content for a 10mg-labeled vial, that's a problem. The product is short of label, regardless of how pure the part that's there might be.
The lab signature and date
A legitimate COA is signed (or digitally signed with a verifiable signature block) by the responsible chemist or lab director. The signature should include the person's name, title, and signing date.
The date matters because peptides degrade over time. A COA from three years ago doesn't tell you anything about what's in the vial today, even if the lot number matches. Reasonable practice is for COAs to be dated within 12 months of the product's first sale.
Spotting a fabricated COA
The peptide market has a long history of fake or misleading COAs. Here are the most common warning signs:
- The same chromatogram on multiple products. If two different compounds — say, BPC-157 and TB-500 — show literally identical chromatograms, one of them is a copy-paste.
- No lab name or contact info. A real lab is publicly identifiable. You should be able to find their website, call them, and verify the COA's authenticity.
- Round numbers everywhere. Real chemistry doesn't produce 100.0% purity, exact 10.00mg fill weights, or perfectly identical retention times across batches. Some variation is normal and expected.
- Refusal to provide the COA before purchase. A vendor who only sends the COA "after you order" is buying time to fabricate one or hoping you won't actually look at it.
- The lab's name doesn't appear anywhere outside that vendor's site. Real third-party labs work with multiple clients. If the lab only appears on one supplier's COAs, it might be the supplier itself in a different costume.
The verification step that takes 5 seconds
The best protection is also the simplest: every Powerbuilt Labs vial ships with a QR code that links directly to the batch-specific COA. Scan it with your phone before uncapping. If the lot number on the document matches the lot number on the vial, you have a valid certificate. If they don't match — or the link is broken — contact us before using the product.
The whole process takes less time than reading this paragraph.
Bottom line
A Certificate of Analysis is only as useful as your willingness to actually read it. If you're paying premium prices for tested research peptides, take the 60 seconds to verify the document against the vial in front of you. The number of "tested" peptide vendors out there is large; the number whose COAs hold up to scrutiny is much smaller.
For more on our specific testing methodology and the third-party lab we work with, see the Quality & Testing page.