A Certificate of Analysis (COA) is the single most important document in research peptide sourcing. It is an independent laboratory report that documents a specific production batch’s measured purity, confirmed molecular identity, and physical characteristics. Without it, you have no objective way to know what is actually in the vial — making it the first thing any serious researcher should verify before using any peptide compound.
This guide explains every section of a peptide COA, how to interpret HPLC chromatograms and mass spectrometry results, what the red flags look like, and what ≥99% purity actually means in practice.
What Is a Peptide Certificate of Analysis?
A COA is issued by an analytical laboratory (ideally third-party and independent from the supplier) after testing a specific production lot of a peptide compound. A complete COA tells you two things:
- Purity — what percentage of the sample is the target peptide (measured by HPLC)
- Identity — whether the sample is actually the peptide it claims to be (confirmed by mass spectrometry)
A COA that reports only purity without molecular identity confirmation is incomplete. A COA without a lot number is not traceable to your specific batch. Both omissions are red flags.
Section 1: Header and Laboratory Information
The COA header should clearly state:
- The name of the testing laboratory (independent, not the supplier’s own facility)
- Laboratory accreditation — ISO 17025 is the international standard for testing laboratory competence. Look for this or an equivalent national accreditation
- The date of analysis — a COA should be reasonably current (ideally within 12 months of your purchase; older than 24 months warrants caution for long-term stability)
- Report number for independent traceability
If the COA does not name a laboratory, was produced in-house by the supplier, or lacks a date, treat the purity and identity claims as unverifiable.
Section 2: Lot/Batch Number Matching
This is the most commonly overlooked verification step. A COA that is not matched to the specific lot in your vial tells you nothing about your actual material — purity can vary significantly between production runs of the same compound.
What to do:
- Find the lot or batch number printed on your vial label
- Confirm the same lot number appears prominently on the COA
- If they do not match, the COA does not verify your compound
PureRawz Australia provides batch-specific COAs for every product, with lot numbers that correspond to the label on your vial.
Section 3: Product Identification
The product identification section should specify:
- Compound name (generic name and any common research name)
- Molecular formula — e.g. C₅₂H₉₈N₁₆O₂₂ for BPC-157
- Theoretical molecular weight — what the mass spectrometry result will be compared against
- CAS number (Chemical Abstracts Service) where applicable — provides an independent reference for the compound’s chemical identity
- Physical description — typically “white to off-white lyophilised powder” for most peptides
Section 4: HPLC Purity Analysis — Reading the Chromatogram
HPLC (High-Performance Liquid Chromatography) is the primary method for determining peptide purity. The sample is dissolved and passed through a chromatography column under high pressure; components separate based on their chemical properties and are detected as peaks by UV absorbance, typically measured at 214–220 nm (the peptide bond absorption wavelength).
What the Chromatogram Shows
The HPLC output is a chromatogram: a graph of UV absorbance vs time (minutes). Each peak represents a distinct compound in the sample:
- The largest peak = your target peptide (expressed as a percentage of total area = purity)
- Smaller peaks = impurities, synthesis by-products, or degradation products
- Baseline noise = should be flat and low — elevated or irregular baseline suggests instrument or sample issues
How Purity Is Calculated
Purity (%) = (Area of target peak ÷ Total area of all peaks) × 100
A result of ≥99% means at least 99% of the UV-absorbing material in the sample is the target peptide; no more than 1% is other compounds. This is the standard PureRawz Australia requires for all research compounds.
What ≥99% Purity Actually Means
It is important to understand what HPLC purity measures — and what it does not:
- HPLC at 214 nm detects UV-absorbing compounds. It does not detect compounds with no UV absorption (e.g. some inorganic salts, residual solvents at low levels)
- ≥99% HPLC purity means the sample is highly pure relative to other peptide-class impurities
- This is why mass spectrometry identity confirmation is still required alongside HPLC purity — purity alone cannot confirm you have the correct molecule
Section 5: Mass Spectrometry — Confirming Identity
Mass spectrometry (MS) measures the molecular mass of compounds in a sample by ionising them and detecting their mass-to-charge ratio (m/z). For peptide identity confirmation, the COA should report:
- Theoretical molecular mass — the calculated mass of the target peptide based on its amino acid sequence
- Observed molecular mass — the mass actually detected in your sample
- Tolerance / accuracy — how close the match is
What Good Agreement Looks Like
On modern LC-MS/MS instruments, mass accuracy should be within 5 parts per million (ppm) of the theoretical mass. For a peptide with a theoretical mass of 1,419 Da (BPC-157), 5 ppm = 0.007 Da variance — an extremely precise match.
Red Flag: Wide Mass Tolerance
A mass spectrometry result reported as “within ±0.1% tolerance” or “within ±1 Da” is a quality concern. On a 3,000 Da peptide, ±0.1% = ±3 Da — wide enough to mask truncated sequences (where synthesis stopped early, producing a shorter, biologically different peptide) or incorrect amino acid substitutions. Premium research-grade COAs should show exact observed masses with instrument-level accuracy.
Section 6: Additional Tests (What to Look For)
Higher-quality COAs may also include:
- Water content (Karl Fischer titration) — lyophilised peptides contain residual moisture; high water content reduces effective purity and shortens shelf life
- Residual solvent testing — solvents used in synthesis (acetonitrile, TFA) should be within ICH Q3C limits
- Amino acid analysis — confirms the correct amino acids in the correct ratios, complementing mass spec identity
- Endotoxin testing — relevant for research requiring sterile injectable preparations
COA Red Flags: What to Watch For
| Red Flag | What It Means |
|---|---|
| No laboratory name on COA | In-house testing; cannot be independently verified |
| No lot/batch number | COA is not traceable to your specific vial |
| Lot number does not match vial label | COA does not verify your compound |
| No date of analysis | Cannot assess freshness or relevance |
| HPLC only; no mass spec | Purity confirmed but identity not confirmed |
| Mass spec tolerance ±0.1% or wider | Insufficient precision to detect sequence errors |
| Purity below 95% | Below minimum research-grade standard |
| Chromatogram shows multiple large peaks | Significant impurity load — sample may be degraded or poorly synthesised |
How PureRawz Australia’s COAs Measure Up
Every compound supplied by PureRawz Australia is independently tested by a third-party analytical laboratory and comes with a batch-specific COA including:
- ≥99% HPLC purity (UV detection at 214 nm)
- Mass spectrometry identity confirmation (theoretical vs observed molecular mass)
- Lot number matched to your vial
- Third-party laboratory name and date
See our Why Buy From PureRawz Australia page for more on our testing and sourcing standards.
Browse COA-verified research peptides →
Frequently Asked Questions
What is a peptide Certificate of Analysis (COA)?
A COA is a document issued by an analytical laboratory reporting the measured purity (by HPLC) and confirmed molecular identity (by mass spectrometry) of a specific production batch of a peptide compound. It is the only objective way to verify what is in a research peptide vial.
What does ≥99% HPLC purity mean on a peptide COA?
It means at least 99% of the UV-absorbing material in the HPLC analysis is the target peptide, with no more than 1% being other compounds (synthesis by-products, degradation products, or impurities). HPLC purity at 214 nm primarily detects peptide-class compounds; mass spectrometry is still required to confirm the target molecule’s identity.
Why is mass spectrometry needed if HPLC shows high purity?
HPLC tells you how pure the sample is; mass spectrometry tells you what it is. A sample could be 99% pure but 99% of the wrong peptide — e.g. a truncated sequence or amino acid substitution that has similar chromatographic behaviour to the target. Mass spectrometry compares the observed molecular mass to the theoretical mass and confirms identity independently of purity.
How do I match a COA to my specific vial?
Find the lot or batch number on your vial label and confirm it matches the lot number stated on the COA. If they do not match, the COA does not verify your specific batch, as purity can vary between production runs.
What is a red flag on a peptide COA?
Key red flags include: no laboratory name (in-house testing); no date; lot number mismatch with your vial; HPLC only with no mass spectrometry; mass spec tolerance wider than ±5 ppm; or purity below 95%. Any of these indicates the COA does not meet research-grade verification standards.
For laboratory and research use only. Not for human or veterinary consumption. Nothing in this article constitutes medical advice.
