A peptide is of verifiable quality when a batch-specific report from an independent laboratory confirms its identity (mass spectrometry), its purity (HPLC), and, where the application requires it, its net peptide content, and when the supplier can show how the material was stored and handled. The checklist below converts that principle into twelve checks that a laboratory procurement officer or principal investigator can apply to any supplier document before a purchase order is raised. All peptides discussed are research materials for laboratory use only, and not for human or veterinary use.
How to use this checklist
The twelve checks fall into four groups: documentation (checks 1 to 4), analytical evidence (checks 5 to 8), contaminants and handling (checks 9 to 11), and regulatory fit (check 12). A supplier does not need to pass every item for every application. A binding assay that depends on accurate molar concentration, for example, places far more weight on net peptide content than a qualitative screen does. What matters is that each item is either satisfied with evidence or consciously accepted with its limitation understood.
The analytical background draws substantially on the peer-reviewed recommendations for the generation, quantification and storage of peptide standards published in Clinical Chemistry, which remains a useful reference for what a defensible peptide specification contains.
Group 1: Documentation
1. The certificate of analysis names your lot
A certificate of analysis (COA) describes a single manufactured lot. It should carry a batch or lot number that matches the label on the vial you receive, the compound name, the report date and the release date. A generic COA that lists a compound and a purity figure without a lot identifier describes a product category, not your material. Check the lot number on the vial against the report before the vial is opened and entered into inventory.
2. The testing laboratory is a separate legal entity
Third-party testing has a specific meaning. One published industry definition requires three conditions to hold at once: the laboratory is a separate legal entity, the report is batch-specific, and the report was actually issued by that laboratory. A report generated in-house, or a logo placed on a supplier-formatted template, meets none of these tests reliably. Look for the laboratory's name, address, accreditation details where claimed, and the analyst or approver identification. For a broader treatment of the concept in an Australian context, see the guide to third-party testing of peptides.
3. The report resolves on the laboratory's own domain
A PDF supplied by a seller is the easiest document to alter. The stronger practice is to locate the unique report ID or verification key and resolve it directly on the issuing laboratory's own domain, not through a link the seller provides. Then compare the retrieved record against your copy field by field: lot number, compound, results and release date should be identical. A discrepancy in any one of them is sufficient grounds to hold the order.
4. Methods and acceptance criteria are stated
A purity percentage is meaningless without the method behind it. The report should state the analytical technique, the column and mobile phase conditions or a method reference, the detection wavelength, and the specification the lot was released against. Without these, two reports showing "99%" cannot be compared.
Group 2: Analytical evidence
5. HPLC chromatogram supplied, not only a number
Reversed-phase HPLC with UV detection estimates product complexity. The Clinical Chemistry recommendations describe it as the assessment of how many components a preparation contains, which is why the chromatogram itself, and not a single summary figure, should accompany the report. Inspect the baseline, the number and relative size of minor peaks, and the integration limits. An HPLC area percentage reflects relative detector response under one method, and it is not necessarily the same as purity by mass.
6. Mass spectrometry confirms identity
HPLC alone does not prove that the main peak is the intended peptide. The authors of the same peer-reviewed recommendations state that a single major chromatographic peak may not itself prove that it is the desired peptide, and that mass spectrometry is what identifies the desired product and mass-related impurities. A credible report lists the expected and observed mass-to-charge values (and the charge states used to derive the molecular mass) and shows that they agree within the instrument's stated tolerance. Where sequence or modification questions arise, such as oxidised methionine, deamidation or an acetylated terminus, MS/MS fragmentation is the more discriminating technique. The practical details are covered in the client's guide to mass spectrometry peptide verification.
7. Net peptide content is reported where dosing accuracy matters
A lyophilised powder contains peptide plus counter-ions (commonly trifluoroacetate or acetate), residual water and sometimes residual salts. The recommendations note that crude peptides lack accurate quantity and purity, and that purified peptides have been chromatographically cleaned of most residual salts, reagents and truncated sequences. Even a purified preparation weighs more than the peptide it contains. For quantitative work, the recommended approach is net peptide content measured by amino acid analysis. If a report offers purity but no content figure, weigh-and-dissolve calculations will overstate the molar amount of peptide.
8. The specification fits the application
The same document makes a further recommendation for pharmaceutical and development settings: ask for detailed specifications and characterisation data (MS, preferably MS/MS, HPLC-UV chromatograms, net peptide content by amino acid analysis), together with the quality-control standard operating procedures linked to those data. It also favours vendors that manufacture their own peptides and provide transparent, linked SOPs. Translate that into a purchasing question: can the supplier trace this lot from synthesis to release, and will they show you the procedure?
Group 3: Contaminants and handling
9. Impurity profile and residuals
The checklist should cover relevant synthesis by-products (truncated and deletion sequences, incompletely deprotected species), residual salts and reagents, and water or moisture content. Residual trifluoroacetate in particular can interfere with cell-based assays, so it is reasonable to ask which counter-ion the lot carries.
10. Sterility and endotoxin where the work requires them
Mass spectrometry and HPLC do not establish sterility or endotoxin status. If a peptide is to be added to cell culture or used in any system sensitive to bacterial contaminants, request microbial and endotoxin testing for that lot, and confirm in writing which tests were performed. Absent results should be recorded as absent, not assumed to be passed.
11. Packaging, storage and freeze-thaw history
The Clinical Chemistry recommendations warn about degradation, adsorption to surfaces, microbial degradation, oxidation, deamidation, photochemical degradation and repeated freeze-thaw cycles. On receipt, therefore, record the following:
- Vial seal integrity and the condition of the outer packaging.
- Whether the shipment stayed within the stated temperature range, and the transit time.
- Protection from light and from air exposure.
- Storage temperature specified by the supplier, and your own storage location and temperature log.
- Reconstitution solvent and concentration, aliquot volumes, and the number of freeze-thaw cycles each aliquot has experienced.
Domestic dispatch shortens transit and removes the customs hold that can leave a package unattended for days. The considerations are summarised in the guide to peptide shipping in Australia. For reconstitution arithmetic, the peptide dilution calculator supports consistent aliquot planning.
Group 4: Regulatory fit
12. Research labelling does not change what the material is
The Therapeutic Goods Administration cautions that performance and image enhancing drugs bought online could be counterfeit or contaminated with toxic chemicals, and their doses or ingredients could differ from the label. It also advises consumers to look for an AUST number as the sign of a TGA-regulated product, and states that a "research" label does not alter the illegality of supplying such drugs for consumer use. Quality documentation, however thorough, is evidence about identity and purity in a laboratory context. It is not evidence that a peptide is safe or suitable for human use, and it should never be presented as such. Regulators have acted against operators who advertised compounded prescription-only peptides without the required approvals and made unsupported safety claims.
For the current regulatory picture, see the client's overviews of TGA peptide regulations in Australia and the legal status of peptides in Australia. Importers should also review the permit timeline for peptide imports and the customs risks associated with overseas shipments.
Documentation warning signs
The following patterns in supplier paperwork are reasons to pause, because each one removes a link in the chain between the report and your vial.
| Observation | What it removes | Action |
|---|---|---|
| No lot number, or a lot number that differs from the vial | Linkage between report and material | Request the correct lot report before use |
| Report format identical across different compounds, with only the name changed | Evidence the compound was actually analysed | Verify on the laboratory's domain |
| Purity figure with no chromatogram or method | Ability to judge the number | Request the raw trace and method |
| HPLC only, no mass spectrum | Identity confirmation | Request MS data or commission it |
| No laboratory name, address or verification route | Independence of the testing | Treat as unverified |
| Purity stated, content absent | Accurate molar quantity | Request amino acid analysis result |
| Human-use or therapeutic claims on a research product | Regulatory fit | Do not rely on the supplier's framing |
The client's article on five checks laboratories use to spot counterfeit peptides extends this list with physical and analytical tests on received material.
Perspective
Our position at Au Peptide Labs is that a purity figure is only as valuable as the verification route behind it. For this reason our stated approach is independent third-party testing to 99%+ purity with a verifiable COA for every batch, so that a researcher can check the report against the lot in hand, not simply accept a claim.
We also consider domestic supply a quality variable and not merely a convenience. Dispatch from Melbourne, within one business day, means no customs delay for the shipment, which shortens the interval during which a lyophilised product sits outside controlled conditions. Discreet packaging accompanies every order.
Laboratories should hold any supplier, ourselves included, to the twelve checks above. Our products are supplied strictly for laboratory research, and a procurement process that demands lot-linked documentation, mass spectrometric identity and transparent handling records is precisely the process we are built to satisfy.
Dr. Authur
Sourcing documented research peptides
Researchers applying this checklist can review the Au Peptide Labs catalogue by research area: Metabolic & GLP-1, Recovery & Repair, GH Secretagogues, Cognitive & Sleep and Longevity & Cellular.
Stocked in Australia and dispatched from Melbourne, each product is supplied with third-party purity documentation for laboratory research use only. Bacteriostatic water, syringes and alcohol wipes are available under Lab Supplies, and Express Post is available for a one-off $10 fee. Custom and bulk orders can be arranged through the Au Peptide Labs site.
Applying the checklist: a worked example
Consider a laboratory ordering a 10 mg vial for a receptor-binding assay. On receipt, the technician reads the lot number from the vial and confirms it matches the COA. The report ID is then resolved on the testing laboratory's website, and the lot, compound and release date are compared with the supplied PDF. The chromatogram shows one dominant peak with small minor peaks, and the mass spectrum lists observed values that agree with the calculated mass of the intended sequence.
Because the assay depends on concentration, the technician then looks for net peptide content. If it is reported at, say, a figure below 100% of the gross weight, the stock solution is calculated from the peptide content and not from the powder mass. Finally, the vial is logged with its arrival temperature, stored as the supplier specifies, and reconstituted into single-use aliquots so that no aliquot undergoes repeated freeze-thaw cycles. The whole process takes minutes once the routine is established, and it leaves an audit trail that supports the integrity of the data produced.
Frequently asked questions
What should I check first when buying peptides for research?
Start with the lot linkage: the batch number on the COA must match the vial. Next, confirm that the report was issued by an independent laboratory and resolves on that laboratory's own domain. Only then evaluate the purity and identity data themselves.
Does 99% HPLC purity mean the vial contains 99% peptide?
No. HPLC area percentage reflects relative detector response under one method and does not account for water, counter-ions or salts. The actual peptide content of the powder is established by amino acid analysis, and it is usually lower than the gross weight.
Is mass spectrometry enough to confirm a peptide is pure?
No. Mass spectrometry supports identity by matching observed and expected mass-to-charge values, but it does not establish purity, sterility or endotoxin status. HPLC and mass spectrometry are complementary, and a complete report contains both.
Can a high-quality research peptide be used by people?
No. Research-grade quality evidence describes laboratory material and does not establish suitability for human use. The TGA states that research labelling does not change the illegality of supplying these drugs for consumer use, and anyone with a health question should consult a doctor.
Sources
- Recommendations for the generation, quantification, storage and handling of peptides (Clinical Chemistry, via PubMed Central)
- How to verify a peptide COA (Axiom Analytics)
- How to tell if your peptide is actually third-party tested (Certik Labs)
- Performance and image enhancing drugs (TGA)
- TGA action against Peptide Clinics Pty Ltd for alleged advertising breaches