A certificate of analysis can contain a lot of information on one page. The useful starting point is to establish which sample it describes, what was tested and how the reported results compare with the stated requirements. Once those pieces are clear, the percentage figures become much easier to interpret.
Start with the report details
A certificate of analysis records results for an identified sample against stated requirements. WHO’s model shows useful report fields: issuing laboratory, sample description, methods, results, specifications and authorisation. The model is used here as a structural reference, not evidence of certification of this material or report.WHO certificate model (opens in a new tab)
Before reading the results, compare the material name, vial size and batch or lot number with the item you are checking. A familiar compound name is only part of the match. If the report describes a different lot, ask the supplier to explain the connection rather than assuming it applies.WHO certificate model (opens in a new tab)Semax report (PDF) (opens in a new tab)
Also find the issuing laboratory, report identifier, revision and relevant dates. These details help you refer to the right document if a question arises. Keep a copy of the complete PDF so that its notes and conclusion stay attached to the result table.WHO certificate model (opens in a new tab)
| Field | Supplied Semax example |
|---|---|
| Material and size | Semax, 10 mg |
| Lot | SEM-41-3J7 |
| Report and revision | MA-SEM-0041, revision 01 |
| Task identifier | DMAS3J7 |
Preserve prefixes, separators and leading zeroes. An absent lot field leaves a match unresolved; a different printed lot is a discrepancy to clarify. An analysis date, issue date or later shipment date does not substitute for the lot link or establish an expiry date.WHO certificate model (opens in a new tab)Semax report (PDF) (opens in a new tab)
Keep identity, purity and content separate
These measurements answer different questions. Reading them together is more informative than choosing the largest percentage on the page.Bachem analytical guide (opens in a new tab)Semax report (PDF) (opens in a new tab)
- Identity
- Does the tested material match the reference or identity criteria used by the laboratory? Read the method and the wording of the conclusion.
- Chromatographic purity
- What share of the integrated chromatographic signal is attributed to the main component under the stated method? Check whether the result is expressed as an area percentage.
- Measured content
- How much of the specified material was measured? On this example it is reported in milligrams per vial, separately from chromatographic purity.
An HPLC or UHPLC area percentage is not a direct measurement of everything in the vial by weight. Water, counterions and residual solvents may require other measurements. Likewise, a percentage described as net peptide content has its own basis and should not be read as an interchangeable purity result.Bachem analytical guide (opens in a new tab)
Identity also depends on the ability of the method to distinguish the intended material from alternatives. ICH's analytical-validation guidance explains that more than one procedure may be needed when a single method does not provide enough discrimination. A report naming LC-MS or LC-HRMS should therefore be read with its reference and identity criteria, rather than as an unlimited guarantee of structure.ICH Q2(R2), section 3.1 (opens in a new tab)
Walk through a supplied certificate
The example is the Semax 10 mg report currently supplied on our product page: report MA-SEM-0041, revision 01, task DMAS3J7, lot SEM-41-3J7. We are using it to explain how to read the document. The values below are transcribed from that report, not new measurements or an independent verification of its issuer or findings.Semax report (PDF) (opens in a new tab)
Find Semax, the 10 mg label claim and lot SEM-41-3J7. Compare these with the item you are checking. Receipt and analysis dates describe separate events.
Open the full certificate (PDF, opens in a new tab)Highlights are a reading aid over the supplied document. The linked PDF is unchanged.
Read across a row, rather than stopping at the result. The specification states the requirement applied; the method identifies how the measurement was made; the verdict records the laboratory's assessment.Semax report (PDF) (opens in a new tab)WHO certificate model (opens in a new tab)
| Reported attribute | Result | Stated specification |
|---|---|---|
| Identity | Conforms | Matches reference |
| Purity (area %) | 99.18% | ≥99.00% |
| Largest single impurity | 0.24% | ≤0.50% |
| Total related substances | 0.82% | ≤1.00% |
| Semax per vial | 9.98 mg | 9.00–11.00 mg |
| Water content | 4.38% | ≤8.00% |
Here, 99.18% is above the displayed minimum purity specification of 99.00%, while 9.98 mg falls within the displayed 9.00–11.00 mg content range. The PDF states that it uses guarded acceptance accounting for method uncertainty. These simple comparisons do not reconstruct that decision rule; the ranges belong to this report and are not universal acceptance limits.Semax report (PDF) (opens in a new tab)
The water result is reported using a different method, Karl Fischer. It should not be added to the chromatographic impurity percentage as though both were parts of the same total. The PDF also lists residual acetonitrile and TFA; this shortened table is a reading aid, so consult the full report for every result and its method.Semax report (PDF) (opens in a new tab)
| Entry | How to read it |
|---|---|
| Not detected (ND) | Below the applicable detection criterion; retain the stated method boundary |
| Less than a value | A reported bound, not an exact zero |
| Not tested or absent result | No reported measurement for that attribute |
| Pass or conforms | The issuer’s categorical conclusion against the stated criteria |
Detection, quantification, reporting and specification limits answer different questions. Detection concerns recognising a signal; quantification concerns measuring an amount with the method’s stated performance; a reporting threshold governs what is listed; a specification sets an acceptance requirement. Keep each label and inequality intact. If the method boundary is too high to assess a stated limit, a less-than result alone cannot resolve that comparison.ICH — Q2(R2), lower range limits (opens in a new tab)WHO certificate model (opens in a new tab)
A passing content row does not require exact equality with the label: both 9.8 mg and 10.2 mg sit inside the illustrative 9.0–11.0 mg interval. That arithmetic illustrates the range, not the outcome of an unreported decision rule. For a result near a boundary, ask how rounding, uncertainty and the stated rule were applied.Semax report (PDF) (opens in a new tab)Eurachem/CITAC — Quantifying uncertainty in analytical measurement (opens in a new tab)
Use the chromatogram as supporting information
A chromatogram plots detector response against retention time. In UV chromatography, an area-purity result is based on integrated peak areas under the method used. The plotted height of the tallest peak is not, by itself, the purity calculation.Bachem analytical guide (opens in a new tab)
The example labels the main Semax peak at 10.20 minutes and gives its area as 99.18%. It also lists related species and states a reporting threshold of 0.05%. Those notes matter: the image is a processed trace with a defined reporting scope, not a complete description of every substance that could be present.Semax report (PDF) (opens in a new tab)
Read the trace alongside the numerical results, method and notes. A large, clean-looking peak does not replace the separate identity or content result. If you need to assess the analytical work in more depth, ask what underlying data and method details are available.Semax report (PDF) (opens in a new tab)Bachem analytical guide (opens in a new tab)
Check what the report leaves unanswered
A passing conclusion applies to the tests and criteria stated in that document. It should not be expanded into a claim about a different lot, every vial in a shipment or a property that was not measured.WHO certificate model (opens in a new tab)NIST sampling principles (opens in a new tab)
This Semax certificate lists no sterility or endotoxin result. Its purity result does not supply either missing measurement. The report also provides no shelf-life period. Keep these as separate absent fields.Semax report (PDF) (opens in a new tab)
Sampling matters too. The example mentions duplicate independent preparations, but that wording alone does not tell you how many vials were sampled across the lot. If your work depends on batch-wide representativeness, ask for the sampling information rather than assuming that repeated preparations are separate randomly selected vials.Semax report (PDF) (opens in a new tab)NIST sampling principles (opens in a new tab)
Reading the report and verifying its provenance are separate tasks. For an authenticity question, seek confirmation of the report identifier and version through an independently located contact for the issuing laboratory. A logo, signature image or a plausible-looking result is not a substitute for that confirmation.SGS — Document-verification FAQ (opens in a new tab)
Having a certificate of analysis is different from being a certified reference material (CRM). NIST’s CRM definition includes specified property values characterised by a metrologically valid procedure, with uncertainty and traceability information. Certification applies to the stated properties, rather than every entry in the document. If a material is needed as a quantitative reference, check that its assigned value and uncertainty support that role; an identity result alone does not establish a concentration scale.NIST — Reference material and certified reference material definitions (opens in a new tab)NIST — Reference materials (opens in a new tab)
Four checks before comparing a laboratory-material quotation
- Identify the material.
- Record the full material description, stated vial size and quantity. Similar names or matching label amounts do not establish that two offers describe the same material.
- Match the lot and sample.
- Compare the quotation, label and report references. Establish how the tested sample relates to the lot offered. Record a missing or different reference as unresolved.
- Check the issuer and provenance.
- Identify the document issuer and, where testing is reported, the laboratory that performed it. Record the report reference and date. Verify the source before relying on a document; a downloadable PDF alone does not authenticate its contents.
- Read the test scope.
- Note what was tested, the method, reported result and limitations. Keep identity, purity and measured amount separate. A result for one property or sample does not establish every property of every vial.
If a field needed for your laboratory's purchasing decision is missing, ask a specific question and keep the response with the quotation.WHO certificate model (opens in a new tab)
Include the product name, stated vial size and report or lot reference if available.Testing and certificates (opens in a new tab)
Sources and further detail
- Supplied Semax 10 mg certificate (opens in a new tab)
MA-SEM-0041, revision 01; task DMAS3J7; lot SEM-41-3J7. Source of the example, figures and document-specific observations. The cited PDF was re-read on 3 October 2026 to check this transcription; its issuer and findings were not independently authenticated.
- WHO — Model certificate of analysis (opens in a new tab)
Technical Report Series 1010, Annex 4 (2018). Background on report structure; not an endorsement of this material or certificate.
- Bachem — Quality control of amino acids and peptides (opens in a new tab)
Sections on identity, purity and product content. Used for the distinction between chromatographic area and material content.
- ICH — Q2(R2): Validation of analytical procedures (opens in a new tab)
Q2(R2), section 3.1: specificity and selectivity. No claim that the supplied methods were validated to this guideline.
- ICH — Q2(R2), lower range limits (opens in a new tab)
Final guideline with 2025 error correction, section 3.2.3. The equations are one estimation approach, not universal substitutes for validation or proof that a supplied method complies.
- Eurachem/CITAC — Quantifying uncertainty in analytical measurement (opens in a new tab)
Third edition (2012), measurement specification, contribution identification and double-counting guidance. Listed as current by Eurachem on the source-check date; original examples avoid the guide's numerical errata.
- NIST/SEMATECH — Populations and sampling (opens in a new tab)
Statistical background on sample-to-population inference; the vial scenarios are original illustrations.
- SGS — Document-verification FAQ (opens in a new tab)
Questions 2 and 12 checked: complete report verification differs from management-system certificate directory lookup.
- Novum Peptides — Testing and certificates (opens in a new tab)
First-party guidance on locating supplied product certificates.
- NIST — Reference material and certified reference material definitions (opens in a new tab)
NIST definitions of reference-material categories and certified properties; no reference-material status assigned to a Novum reagent.
- NIST — Reference materials (opens in a new tab)
NIST overview of reference-material roles and assigned values; used for the distinction between an identity result and a quantitative reference.
Revised from the existing source dossier on 3 October 2026. Values and dates are transcribed from the supplied report, not new measurements or independent authentication. This article has not undergone independent scientific peer review.