Most peptide COAs pass the checklist and tell you almost nothing. This guide explains what a Certificate of Analysis actually measures, what it cannot measure, how to verify one independently, and how to spot a document that has been recycled, altered, or fabricated.
A Certificate of Analysis is a batch-specific laboratory document that records the results of analytical testing performed on a specific lot of a research compound. The key word is batch-specific. A COA that is not tied to the exact lot number on your vial is not meaningful documentation for your vial — it is documentation for a different production run that may or may not match what you received.
A COA is a record of what testing showed. It is not a guarantee. It documents what a submitted sample measured on the day it was tested by the issuing laboratory. It does not confirm that every vial in that batch was tested, that the sample submitted was representative of the full batch, or that the compound has remained stable since testing.
A COA from a third-party, independent laboratory is the only form that carries meaningful evidentiary weight. In-house COAs — where the supplier tests their own product — carry an inherent conflict of interest. They may still be accurate, but they cannot be independently verified in the same way a third-party report can.
A fully documented peptide COA addresses four categories: identity (is this the correct molecule?), purity (is the molecule free of synthesis impurities?), content (how much actual peptide is in the vial by mass?), and contamination (endotoxins, heavy metals, residual solvents). Most COAs in the research peptide market address only identity and purity. Content and contamination testing are typically add-ons that meaningful suppliers include.
Third-party testing means an independent laboratory — one with no financial relationship to the outcome of the test — performed the analysis on a submitted sample. The laboratory issues the report directly under its own name, and the report can be verified through the laboratory's own records.
In-house testing means the supplier's own laboratory performed the analysis. The supplier controls the testing methodology, the equipment calibration, the sample selection, and the data reporting. There is no external check on any of those variables. Some suppliers present in-house COAs with professional formatting that mimics third-party reports. The distinguishing factor is always whether you can verify the report independently by contacting the issuing laboratory directly.
Peptide synthesis is a batch process. Each synthesis run produces a unique lot with its own characteristics — slight variations in raw materials, synthesis efficiency, purification yield, and lyophilization conditions mean that no two batches are identical even for the same compound from the same supplier. A COA from batch A tells you nothing about batch B, even if they are labeled the same compound at the same purity.
When reviewing a COA, confirm that the batch or lot number on the COA matches the batch or lot number on your vial label. If a supplier cannot provide a batch-matched COA for your specific order, that is a meaningful gap in their quality documentation.
High-Performance Liquid Chromatography (HPLC) is the standard method for quantifying peptide purity. It works by separating the components of a sample as they travel through a stationary phase column at different speeds, detecting each component as it exits using a UV detector. The result is a chromatogram — a series of peaks where each peak represents a detectable compound in the sample.
Purity is calculated as: Area of target peptide peak ÷ Total area of all detected peaks × 100. This is reported as "Area%" and represents what percentage of UV-absorbing material in the sample is the target compound versus impurities.
HPLC detects peptide-related impurities from synthesis: deletion sequences (peptides missing one or more amino acids), truncated fragments, insertion errors, and oxidized or modified side chains. These are the impurities that arise during solid-phase peptide synthesis and that purity specifications are designed to control.
HPLC cannot confirm that the compound being measured is the correct peptide. A sample containing a different peptide of similar size and polarity to the intended compound can appear as a high-purity peak on HPLC. Without mass spectrometry, you are measuring how clean the sample is — not whether it is the right compound.
A properly documented HPLC result should include: the purity percentage (Area%), the column type and dimensions, the mobile phase composition (typically acetonitrile/water with TFA or formate buffer), the gradient program, the detection wavelength (typically 214 nm or 220 nm for peptides), the injection volume, and the flow rate. These parameters define the analytical method. Without them, the result cannot be independently reproduced or validated.
| Purity (HPLC Area%) | Classification | Research suitability |
|---|---|---|
| ≥99% | Research grade | Suitable for quantitative assays, publication-grade work, and sensitive biological models |
| 95–98% | Standard grade | Acceptable for preliminary screening; impurity load may affect sensitive assays |
| 90–95% | Technical grade | Suitable for non-critical applications only |
| <90% | Below research grade | Not appropriate for reproducible research |
Mass spectrometry (MS) — typically performed as liquid chromatography-mass spectrometry (LC-MS) in peptide analysis — confirms molecular identity by measuring the mass-to-charge ratio of the compound. Every peptide has a unique molecular weight determined by its exact amino acid sequence. Mass spectrometry confirms that the measured molecular weight matches the theoretical mass calculated from the expected sequence.
This is the test that answers: Is this actually the peptide it claims to be? HPLC tells you how pure it is. MS tells you what it is.
A COA with mass spectrometry data should include the observed m/z (mass-to-charge) value or the calculated molecular weight derived from the MS spectrum. You can verify this against the theoretical molecular weight for the peptide, available from PubChem (pubchem.ncbi.nlm.nih.gov) using the compound name or CAS number.
For example, BPC-157 has a theoretical molecular weight of 1419.53 Da. A mass spectrometry result consistent with this value (within analytical error of ±0.1–0.5 Da for small peptides) confirms identity. A significantly different mass indicates a wrong compound, sequence error, or degradation product.
Look up the theoretical molecular weight for any research peptide on PubChem using the compound name or CAS number. Compare this against the observed mass on the COA. A discrepancy of more than 1–2 Da warrants follow-up with the supplier before using the batch.
Some suppliers provide COAs with HPLC purity only and no mass spectrometry data. This is a meaningful gap. A compound can be 99% pure by HPLC while being the wrong molecule — a deletion sequence, a different peptide, or a structurally similar synthetic impurity. Without MS confirmation, the identity claim rests entirely on the supplier's process controls, not on analytical evidence. For research that depends on the specific activity of a known peptide sequence, MS confirmation is not optional.
This is the single most commonly misunderstood aspect of peptide COA data, and the gap that allows suppliers to sell less peptide than advertised while technically complying with their purity claims.
Purity (Area% HPLC) tells you what percentage of the UV-absorbing material in the sample is the target peptide versus synthesis impurities. A 99% pure peptide is 99% free of synthesis-related impurities.
Net peptide content tells you what percentage of the total vial mass is actual peptide, accounting for everything that is not peptide: counterion salts, water of hydration, and residual solvents. These non-peptide components are invisible to HPLC purity measurement because they do not absorb UV light at peptide detection wavelengths.
Most research peptides are supplied as acetate salts. During purification, trifluoroacetic acid (TFA) is commonly used and must be exchanged post-purification, typically leaving the peptide as its acetate salt form. Acetate ions add mass to the final product but contribute no biological activity.
A 10mg vial labeled at 99% HPLC purity might contain only 7.5–8.5mg of actual peptide, with the remaining 1.5–2.5mg being acetate counterion, water of hydration, and other non-peptide mass. This is the standard chemistry of lyophilized peptide formulation — but it means the effective peptide dose differs from the labeled vial weight, which matters for research dosing calculations.
| Component | Typical % of vial mass | HPLC visible? | Biological activity |
|---|---|---|---|
| Peptide | 75–90% | Yes | Yes |
| Acetate counterion | 5–15% | No | No |
| Water of hydration | 2–8% | No | No |
| Residual solvents | <1% | No | No |
A complete COA should report both HPLC purity (Area%) and net peptide content (actual peptide mass in the vial in mg). If a COA reports only purity and the labeled vial weight, you do not have the full picture. Janoshik's standard service includes a quantitative mass result reporting measured peptide content per vial — this is distinct from and more informative than the HPLC purity percentage alone.
Endotoxins are lipopolysaccharide (LPS) fragments from the outer membrane of gram-negative bacteria. They are introduced during synthesis through contaminated reagents, equipment, or handling, and they survive standard purification processes. They are not visible on HPLC chromatograms and are not addressed by mass spectrometry. The only way to detect them is a dedicated endotoxin assay.
The standard test is the Limulus Amebocyte Lysate (LAL) assay, which uses clotting factors from horseshoe crab blood to detect bacterial LPS. Results are reported in Endotoxin Units per milliliter (EU/mL) or per vial (EU/vial). The FDA limit for parenteral drugs is 5 EU/kg body weight per hour, which translates to roughly 0.5 EU/mL for typical research concentrations.
Endotoxins trigger Toll-like receptor 4 (TLR4) signaling and downstream NF-κB activation, inducing a pro-inflammatory cytokine cascade. In cell culture, even sub-toxic endotoxin concentrations can activate inflammatory pathways, confound proliferation and viability assays, alter receptor expression, and produce effects that appear to be caused by the peptide being studied — when they are actually caused by the contaminant. In animal models, endotoxin contamination can produce systemic inflammatory responses that mask or amplify the peptide's actual effects, rendering the research non-reproducible.
If your research involves cell culture, primary cells, immune cells, or in vivo models, require endotoxin testing data before using any peptide batch. An endotoxin result ≤1 EU/mL is generally acceptable for most research applications; ≤0.1 EU/mL is preferred for highly sensitive immune or cytokine assays.
Janoshik offers LAL endotoxin testing as a paid add-on to their standard purity and identity testing. It is not included in the base analysis. Suppliers who include endotoxin results on their COAs have paid for additional testing beyond the minimum — this is a meaningful signal of quality commitment. All Evo Peptides batches include Janoshik endotoxin results, published in our COA library.
Janoshik Analytical is an independent analytical laboratory based in the Czech Republic that specializes in peptide testing for the research compound market. They are widely used because they provide publicly verifiable reports through a searchable database — meaning any COA they issue can be independently confirmed by anyone with the report credentials, without contacting Janoshik directly.
This verifiability is what distinguishes Janoshik from many other testing providers. A supplier cannot alter a Janoshik result after it has been issued without the alteration being immediately detectable on verification.
| Test | Included in base service | What it confirms |
|---|---|---|
| HPLC purity | Yes | Percentage of target peptide vs synthesis impurities (Area%) |
| Quantitative mass | Yes | Measured peptide content per vial in mg |
| Mass spectrometry (LC-MS) | Add-on | Molecular identity confirmation via mass-to-charge ratio |
| LAL endotoxin | Add-on | Bacterial endotoxin concentration in EU/mL or EU/vial |
| Heavy metals | Add-on | Arsenic, cadmium, lead, mercury by ICP-MS |
| Sterility | Add-on | Absence of viable microorganisms |
All Evo Peptides batches are tested by Janoshik for HPLC purity, quantitative mass (net peptide content), and mass spectrometry identity confirmation. Every COA is publicly verifiable using the Task Number and Unique Key on the report. Our full COA library is published at evopeptidesus.com/coas. 8-point testing including endotoxin, heavy metals, and sterility via ILS Labs — coming soon.
COA fraud is a documented problem in the research peptide market. The most common forms are fabricated documents created without any testing, recycled documents from a legitimate test applied to a different batch, and altered documents where a genuine COA has had its purity figure or batch number modified. Understanding these patterns reduces the risk of being misled.
A common fraud pattern in the research peptide market involves a supplier obtaining a legitimate COA for one high-quality batch and then applying that COA document to subsequent batches that were either not tested or tested and failed to meet specifications. Indicators include the same task number appearing across multiple orders placed at different times, a test date that does not align with the order date, and batch numbers on the COA that do not match batch numbers on vial labels.
This is why batch-specific verification matters. If the task number and unique key verify correctly on Janoshik's portal but the batch number does not match your vial, you have verified a real Janoshik test — just not a test of what you actually received.
Use this checklist when evaluating a COA from any research peptide supplier. A COA that passes all items provides high confidence in the quality documentation. Use this before purchasing from any new supplier or accepting a new batch from an existing one.
Janoshik third-party tested. HPLC purity, net peptide content, and mass spectrometry identity confirmation on every batch. 8-point ILS Labs testing coming soon. Same-day shipping before 3 PM CST from Wisconsin.
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