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A Certificate of Analysis (CoA) is the primary quality assurance document for any research-grade chemical compound, including peptides. It records the results of analytical testing performed on a specific batch of material, confirming that the compound meets defined purity and identity specifications. For researchers sourcing peptides in Australia, the CoA is your primary defence against receiving a substandard or incorrectly synthesised compound.
Unfortunately, not all CoAs are created equal. The research peptide market includes suppliers who produce professional-looking CoA documents that contain limited useful information, reference generic rather than batch-specific testing, or cite in-house laboratory results rather than independent third-party analysis. Learning to read and critically evaluate a CoA is a practical skill with direct implications for research quality.
A credible CoA for a research peptide should include results from two distinct analytical methods that answer two distinct questions.
HPLC (High-Performance Liquid Chromatography) — How Pure Is It?
HPLC separates the components of a sample based on their interactions with a stationary phase and a mobile phase, producing a chromatogram that shows the proportion of the total signal attributable to the target compound versus other components. The purity figure expressed as a percentage — for example, 98.7% — represents the proportion of the sample that is the target peptide.
What HPLC tells you: how much of what is in the vial is the compound you ordered, versus impurities, synthesis by-products, truncated sequences, or degradation products.
What HPLC does not tell you: whether what is in the vial is the right compound. A sample could be 99% pure and still be the wrong peptide entirely. This is why HPLC alone is insufficient.
The research-grade standard is 98% purity or higher. Some suppliers achieve 99%+, which is the appropriate benchmark for serious research applications.
Mass Spectrometry (MS) — Is It the Right Compound?
Mass spectrometry determines the molecular mass of compounds in a sample by ionising them and measuring the mass-to-charge ratio of the resulting ions. For peptides, this allows researchers to confirm that the molecular weight of the compound matches the theoretical molecular weight of the target sequence.
What MS tells you: whether the compound in the vial has the correct molecular weight, providing strong evidence that it is the target peptide rather than a different compound or a scrambled sequence.
What MS does not tell you: purity. A sample could pass MS confirmation (correct compound present) while being only 60% pure. This is why MS and HPLC are complementary rather than substitutable.
Together, HPLC purity and MS identity confirmation provide a meaningful quality picture. Either test alone is insufficient for research purposes.
Batch or Lot Number
Every CoA should reference a specific batch or lot number that corresponds to the physical product in the vial. This is how you can verify that the testing was performed on the material you received, not on an earlier, different, or more favourable batch. If a supplier provides a generic CoA with no batch number, or one that cannot be matched to the batch number on your vial, this is a significant red flag.
Testing Laboratory Information
The CoA should identify the laboratory that performed the analysis — ideally by name, with contact information or a laboratory accreditation number. Independent third-party laboratories can be verified. If the CoA lists only “in-house quality control” or a laboratory name that cannot be independently verified, the results should be treated with scepticism.
Test Date
The testing date should be reasonable relative to the manufacture date and your purchase date. A CoA dated three years ago may not reflect the current batch’s condition, particularly if the compound has been stored poorly.
Compound Name, Sequence, and Molecular Formula
The CoA should clearly state the compound name, the amino acid sequence (for peptides), the molecular formula, and the theoretical molecular weight. These allow you to cross-reference the MS data against published specifications for the compound.
Water Content (Karl Fischer Titration)
Some advanced CoAs include water content data from Karl Fischer titration. Lyophilised peptides absorb moisture over time, and high water content reduces the effective peptide content per unit mass. This is particularly relevant for researchers who need precise dosing in their experiments — a compound that is 98% pure by HPLC but 15% water by mass contains significantly less active peptide per milligram than expected.
No batch number or a batch number that does not match the vial: Testing was not performed on your specific material.
In-house laboratory results only: The manufacturer is marking their own homework. Independent verification is absent.
HPLC result only, no MS: Identity has not been confirmed. The sample may be pure but wrong.
MS result only, no HPLC: Purity has not been confirmed. The target compound is present but may be significantly contaminated.
Purity below 95%: Sub-research-grade material that is inappropriate for serious laboratory use.
Generic document applicable to multiple batches: Indicates systematic rather than batch-specific testing, which does not reflect the quality of the specific product you received.
No laboratory name or contact information: The testing laboratory cannot be independently verified.
Results that look suspiciously round: Real analytical results are rarely clean round numbers. A CoA showing exactly 99.0% purity with no decimal variation across multiple compounds may indicate fabricated data.
When ordering from a domestic Australian supplier, you should be able to request a batch-specific CoA before or at the time of purchase. Reputable suppliers maintain these documents and can provide them on request without friction.
Some suppliers publish CoAs on their website indexed by batch number, allowing researchers to verify results independently. Others provide them via email upon request. A supplier who is reluctant to provide a CoA, unable to produce one, or who provides a document that does not meet the criteria above should not be trusted with your research budget.
If you want to go further, you can contact the listed testing laboratory to verify that the CoA was genuinely issued by them for the stated batch. This is rarely necessary with established domestic suppliers but is a legitimate verification step for new or unfamiliar sources.
For researchers who work with peptides regularly, establishing a consistent CoA review practice as part of the procurement process is good laboratory hygiene. Maintaining a file of CoAs for each batch received — cross-referenced to your experimental records — allows you to retrospectively investigate any anomalous results and demonstrates due diligence in your research documentation.
Australian Peptides provides batch-specific CoAs from independent third-party laboratories for all products, including both HPLC purity and mass spectrometry identity data. CoAs are available on request for any current or recent batch.
New batch COAs and restock alerts, sent when they happen.
Need more information about Australian Peptides? Get in contact with us via the email below and Australian Peptides will assist you promptly.
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