Short answer
A useful COA connects a defined sample to a defined test and a pre-defined limit.
The World Health Organization defines a certificate of analysis as the test procedures applied to a particular sample, the results obtained, and the acceptance criteria used. That means “99%” without a method, unit, batch, and specification is not a complete quality statement. WHO laboratory guidance
Document first
Read the COA in two passes
First verify that the document belongs to the material in front of you. Only then interpret the analytical results. A technically impressive report for the wrong lot has no procurement value.
Traceability
Laboratory, report number, sample name, lot, dates, submitter, version, and sign-off.
Analytical meaning
Method, measured attribute, result, unit, uncertainty or method limit where relevant, specification, and conclusion.
| Field | What to look for | Warning sign |
|---|---|---|
| Laboratory and report ID | A legal laboratory name, address or contact route, unique report number, issue date, and authorized sign-off. | A cropped image, seller-made summary, or report with no independent lookup path. |
| Sample identity | The material name, form, supplier or submitter, and an unambiguous sample description. | A generic label such as “peptide sample” that cannot be tied to the tested item. |
| Batch or lot | The same lot identifier on the report, product label, invoice, and receiving record. | A report for a different lot, or stock sold without a visible batch identifier. |
| Method and result | The named procedure, numerical result where appropriate, units, and enough method context to interpret it. | “Pass” or “99%” without saying what was measured, how, or in which units. |
| Specification | A pre-defined acceptance limit beside each result and a clear pass/fail conclusion. | A result presented without a limit, making “acceptable” impossible to evaluate. |
| Sampling and dates | Sampling or receipt date, test date, manufacture date when available, and report version. | An old report reused for newly manufactured or differently labelled stock. |
A manufacturer COA and an independent laboratory report answer different trust questions. Independent testing reduces one conflict of interest, but it still represents the submitted sample and depends on sampling, chain of custody, method suitability, and report integrity.
Do not collapse terms
Separate the five quality questions
Regulatory quality frameworks treat identification, assay, impurities, and microbiological testing as distinct parts of a specification. For complex or biological materials, potency may also require a product-relevant activity assay. One test can sometimes contribute to more than one answer, but the report must show that the method was designed and validated for each stated purpose. FDA / ICH Q6A
Identity
Is the target molecule actually present?
- Relevant evidence
- A suitably specific identity procedure, often supported by an orthogonal technique such as mass spectrometry.
- Does not answer
- How much is present, whether every impurity was measured, or whether the sample is sterile.
Purity / impurity profile
What else is detected under the stated method?
- Relevant evidence
- A validated, selective chromatographic method with stated detector conditions, integration approach, and impurity limits.
- Does not answer
- The total mass of target material in a vial or substances the method does not detect.
Content / strength
How much target material is in the tested unit?
- Relevant evidence
- A quantitative assay against a suitable reference standard, reported with units and an acceptance range.
- Does not answer
- Biological activity unless the assay was designed and validated to measure activity.
Biological potency
Does the material produce a defined biological activity?
- Relevant evidence
- A product-relevant, quantitative biological assay with a reference preparation and stated criteria.
- Does not answer
- Chemical purity, vial content, sterility, endotoxin, or suitability for a different protocol.
Microbiological quality
Were the required contamination controls tested?
- Relevant evidence
- Separate, fit-for-purpose methods for sterility, bioburden, endotoxin, or other protocol-specific risks.
- Does not answer
- Identity, chemical purity, or biological potency.
Content is not automatically potency. A quantitative assay can establish how much target material was measured. “Potency,” when used to mean biological activity, requires an assay designed around a defined biological result and an appropriate reference. FDA potency definition
Method literacy
What HPLC and mass spectrometry do—and do not—prove
Separation
HPLC
High-performance liquid chromatography separates detected components under a defined set of conditions. With a suitable validated method, it can support impurity testing and quantitative assay.
Check the report for
- Column and method identification
- Detector type and wavelength or response mode
- Reference standard and calibration approach
- Retention time, system suitability, and integration
- Whether the result is peak-area purity or content assay
Mass evidence
MS
Mass spectrometry measures the mass-to-charge ratio of ions or molecular fragments. It can strongly support identity, especially as an orthogonal technique paired with chromatography.
Check the report for
- Observed and expected mass-to-charge values
- Ionization mode and charge-state interpretation
- Mass tolerance or acceptance rule
- Reference or library comparison where applicable
- Whether intact mass or fragment evidence was assessed
Why “HPLC 99% + correct mass” is still incomplete
- A chromatographic percentage is method- and detector-dependent. It is not automatically the mass of target peptide per vial.
- Compounds with weak or no response under the chosen detector conditions may not be represented by the same area calculation.
- A matching mass supports identity but does not by itself establish amount, complete impurity coverage, or every structural distinction.
- Neither HPLC nor MS is a sterility or bacterial endotoxin test.
ICH Q6A states that a single chromatographic retention time is not sufficiently specific for identification and points to combined approaches such as HPLC/MS. ICH Q2(R2) likewise recommends orthogonal procedures when needed for selectivity. Identity guidance Analytical validation guidance
NIST describes MS as measurement of mass-to-charge patterns and notes that structurally similar compounds can produce highly similar spectra. This is why the question is not “Was MS used?” but “Was the complete analytical package sufficiently selective for this material?” NIST Technical Note 2297
Separate controls
Sterility and endotoxin are not interchangeable
Sterility
Sterility testing looks for viable microorganisms under a specified compendial or validated procedure. It is sample-based and cannot inspect every closed unit in a lot.
Bacterial endotoxin
Endotoxin testing detects or quantifies bacterial endotoxins using a separate method. Endotoxin can be a concern even when no viable bacterium is recovered.
A credible microbiological result names the method, tested sample, result, units where applicable, method sensitivity, and acceptance criterion. A bare “sterile” or “endotoxin passed” label is not enough to judge method suitability or the limit applied. FDA endotoxin guidance
Sampling limit
A passing sterility test is not proof about every unit.
WHO explains that sterility tests use representative samples because every sealed container cannot be opened and tested. When only a small fraction of a large lot is contaminated, the probability of sampling a contaminated unit can be low. Sterility assurance therefore also depends on validated sterilization or aseptic processing, environmental controls, and batch records. WHO sterility testing
Do not infer clinical suitability. Even a complete analytical panel does not turn an unapproved research-use material into a medicine or establish suitability for administration to a person or animal.
Independent confirmation
Verify a third-party report in six steps
- 01
Identify the laboratory independently
Use the laboratory’s own domain, accreditation-body directory, or an independently obtained contact route. Do not rely only on the phone number or QR destination printed by the seller.
- 02
Retrieve or confirm the report
Enter the report identifier in the laboratory’s verification portal when one exists. If it does not, ask the laboratory to confirm the report number, issue date, sample label, and reported results.
- 03
Match the physical batch
Compare the exact batch or lot string across the report, vial or container, invoice, and receiving record. A compound name alone is not a match.
- 04
Check who supplied the sample
Distinguish a supplier-submitted sample from an independently selected sample. Both can generate valid analytical data, but the sampling chain changes what the result can represent.
- 05
Check the laboratory’s scope
If accreditation is claimed, confirm the accreditation is current and that its published scope covers the relevant test or discipline. A logo is not blanket accreditation for every method.
- 06
Review the complete evidence set
Look for the method, units, specification, result, chromatogram or spectrum where relevant, version, and sign-off. A static PDF is a summary—not the instrument’s full audit trail or raw dataset.
Accreditation check
Verify the test scope, not only the badge.
ISO/IEC 17025 sets requirements for laboratory competence, impartiality, and consistent operation. Use the ILAC directory to find a recognized accreditation body, then inspect that body’s listing for the laboratory and relevant scope. ISO/IEC 17025 ILAC directory
Stop and investigate when
- The report cannot be found or confirmed by the laboratory.
- The batch on the item differs by even one character.
- The seller presents a chromatogram without a signed report.
- Dates, sample description, or laboratory branding conflict.
- “Third-party tested” appears without naming the third party.
- A QR code resolves only to a seller-controlled image or page.
- Integration, units, or acceptance criteria are missing.
FDA data-integrity guidance explains that a number without its metadata is not meaningful and that a static chromatogram can hide reprocessing choices available in the dynamic record. A public PDF can support review, but it is not equivalent to the complete instrument data, metadata, and audit trail. FDA data-integrity guidance
Local route risk
Ask for evidence about storage and transport in Thailand
A release COA describes the tested sample at a point in time. It does not prove that later storage and delivery preserved the material. Thailand routes can include hot loading areas, parked vehicles, humid handling environments, airport transfers, and last-mile delays, so the transport plan must be tied to the material’s stated stability limits.
Seven questions to ask before dispatch
- 01
What storage range is stated for this exact material and form, and what stability data support it?
- 02
Where does the shipment begin, how long is the expected route, and which carrier handles the final mile?
- 03
Was the shipper or packaging configuration qualified for the route’s expected temperature range?
- 04
Is a calibrated temperature indicator or data logger included when the material is temperature-sensitive?
- 05
What happens after an excursion: quarantine, documented stability assessment, replacement, or rejection?
- 06
How are humidity, light, vibration, and seal damage controlled where they are relevant to the material?
- 07
Can the supplier provide dispatch time, batch identity, packaging configuration, and delivery records?
Do not invent a universal storage temperature for “peptides.” Required conditions depend on the exact substance, form, container, duration, and validated stability data. WHO guidance calls for transport according to labelled or manufacturer-described conditions, documented records, and investigation of transit problems. WHO storage and distribution guidance
Practical artifact
Research-material procurement checklist
Use the same standard for every supplier. A missing item should remain visibly “unknown” until it is resolved; it should never silently become a pass.
Before approving a supplier
Define the required identity, content, impurity, and microbiological specifications before reviewing a COA.
Verify the supplier’s legal identity, contact details, return process, and research-use terms.
Confirm the testing laboratory and any claimed accreditation through an independent source.
Ask who selected and submitted the sample, and how it was linked to the production lot.
Require a batch-specific report rather than a representative or undated example.
Before accepting the report
Match the report number, sample name, lot number, dates, and laboratory sign-off.
Separate identity, purity, content, potency, sterility, and endotoxin results—do not let one substitute for another.
Check the method, numerical result, unit, detection or quantitation limit where relevant, and acceptance criterion.
Confirm the report directly with the laboratory or its verification portal.
Record any missing tests as unknown, not as passed.
When the shipment arrives
Match the received lot to the approved COA and purchase record.
Inspect the seal, label, container, and transport packaging for damage or substitution.
Review temperature-monitoring evidence and document any excursion before moving material into inventory.
Quarantine mismatched, damaged, undocumented, or excursion-affected material pending a documented decision.
Retain the report, verification evidence, shipping record, and receiving record together.
Release decision
Accept only when identity, specification, report authenticity, lot match, and transport records meet the laboratory’s pre-defined requirements. Otherwise quarantine, investigate, or reject.
Evidence base
Primary and standards sources
These sources support the document fields, analytical distinctions, laboratory-verification principles, and distribution controls used in this guide. Standards and regulatory expectations can change; verify the current version required by your institution and jurisdiction.
- 01
World Health Organization
WHO good practices for pharmaceutical quality control laboratories (TRS 1052, Annex 4)Defines a COA, batch identity, analytical records, and acceptance criteria. - 02
U.S. Food and Drug Administration / ICH
Q6A: Specifications, test procedures, and acceptance criteriaSeparates identification, assay, impurities, and microbiological quality tests. - 03
U.S. Food and Drug Administration / ICH
Q2(R2): Validation of analytical proceduresExplains selectivity, accuracy, precision, range, and orthogonal procedures. - 04
U.S. Food and Drug Administration
Biotechnology inspection guideDefines biological potency and the role of product-specific activity tests and reference preparations. - 05
National Institute of Standards and Technology
Similarity measures of mass spectra in Hilbert spacesDescribes mass-to-charge measurement and limits when spectra are structurally similar. - 06
World Health Organization
Sterility testingExplains sampling limits and the role of manufacturing controls in sterility assurance. - 07
U.S. Food and Drug Administration
Pyrogen and endotoxins testing: questions and answersCovers bacterial endotoxin methods and acceptance criteria. - 08
International Organization for Standardization
ISO/IEC 17025:2017Sets competence, impartiality, and consistent-operation requirements for testing laboratories. - 09
International Laboratory Accreditation Cooperation
ILAC MRA signatory searchProvides a route to recognized accreditation bodies and their accredited-facility directories. - 10
U.S. Food and Drug Administration
Data integrity and compliance with drug CGMPExplains metadata, traceability, HPLC audit trails, and the limits of static records. - 11
World Health Organization
Good storage and distribution practices (TRS 1025, Annex 7)Covers labelled storage conditions, transport risk, traceability, excursions, and distribution records.
Quick checks
Common COA questions
Does 99% HPLC purity prove that a peptide vial is 99% peptide?
No. An HPLC purity value describes the result produced by a particular chromatographic method and detector. It does not automatically establish the total mass of target peptide in the vial, identity, sterility, endotoxin level, or compounds the method did not detect.
Does mass spectrometry prove peptide identity?
Mass spectrometry can strongly support identity by measuring mass-to-charge patterns, especially when combined with chromatography and a suitable reference. Mass agreement alone does not establish quantity, complete purity, sterility, or every structural detail.
Does a passed sterility test prove every vial is sterile?
No. Sterility testing examines a sample from a batch and has statistical limits. Sterility assurance also depends on validated manufacturing and aseptic controls, batch records, and environmental controls.
What must match between a third-party report and a shipment?
At minimum, the exact batch or lot identifier, material name and form, supplier or submitter context, and relevant dates should be consistent. The report should also be independently verifiable through the testing laboratory.
