Red flags on a certificate of analysis
A certificate of analysis is a lab’s word on one sample. Some leave out what a lab report is expected to carry, or overstate what the lab is accredited to do. Below are checks to make and questions to ask, each tied to an accreditation or regulatory document.
Check that the lab is named and that its accreditation can be looked up and covers the test reported. Check that each test shows its method, its acceptance limit and a numerical value with units. Check the lot, the dates and who authorized the report. Where anything is missing, ask the lab or the supplier.
What accreditation means, and what it covers
ILAC, the international body for accreditation bodies, defines the term: “Accreditation is the independent evaluation of conformity assessment bodies against recognised standards” to carry out specific activities. For testing laboratories the standard is ISO/IEC 17025.[1]
Accreditation is granted for a list of activities, not for a building. ILAC’s guideline on scopes says: “The scope of accreditation of a laboratory is the formal and precise statement of the activities which the laboratory is accredited for.”[2] A lab can be accredited for one test and not for another. An accreditation logo on a report does not, by itself, tell you which tests it covers.
Checks to make
ISO/IEC 17025 itself is paywalled, so its reporting clause is cited through a NIST crosswalk that summarises it.[4] ICH Q7 is written for the manufacture of active pharmaceutical ingredients, not research material.[5] It is used here only as a picture of what regulated practice expects.
| Check | What to look for | Source of the expectation |
|---|---|---|
| The lab is identified | The name and address of the lab that did the testing | ISO/IEC 17025 reporting clause, via NIST[4] |
| The accreditation can be looked up | An accreditation body and number you can find in that body’s own directory | NRC procurement guidance[6]; ILAC signatory search[7] |
| The test is inside the scope | The method on the report appears in the lab’s published scope | ILAC-G18[2]; NRC procurement guidance[6] |
| Out-of-scope tests are marked | A note that marked tests are not covered by the accreditation | ILAC-P8[3] |
| Each test names its method | A method identifier beside each value | ISO/IEC 17025, via NIST[4] |
| Limits and numbers are given | The acceptance limit and the numerical value for each test | ICH Q7, section 11.4[5] |
| Every number has a unit | %, mg, EU/mL | ISO/IEC 17025, via NIST[4]; FDA[8] |
| The sample is tied to a lot | A lot or batch number that matches the material | ICH Q7[5] |
| The dates are there | Date received and date the report was issued | ISO/IEC 17025, via NIST[4] |
| Someone authorized it | The name or identity of the person authorizing the report | ISO/IEC 17025, via NIST[4]; ICH Q7[5] |
| Subcontracted work is named | Which tests another lab performed | ISO/IEC 17025, via NIST[4]; ICH Q7[5] |
For a walk through a whole report, see How to read a certificate of analysis.
Look up the accreditation yourself
A logo is a claim; the lookup is the check. U.S. Nuclear Regulatory Commission guidance on procuring test services puts the first step as: “Verify the laboratory is accredited to ISO/IEC-17025 by an ILAC signatory.” The next is to verify that the service is in the scope, which for testing means the method.[6] ILAC’s site offers a signatory search and a search of accredited bodies.[7]
Scopes can be fixed or flexible; one U.S. accreditation body, A2LA, publishes a policy on flexible scopes.[9]
ILAC-P8 also limits where accreditation symbols may appear. Accreditation symbols “shall not be placed on the products or items which have been subjected to conformity assessment,” with some label exceptions.[3]
Watch for tests outside the scope
ILAC-P8 says there shall be “nothing in any conformity assessment report or certificate or in any attachments or other materials that implies” that an activity is covered by the scope when it is not.[3] It gives example wording for the disclaimer: “The conformity assessment activities marked * are not covered by the scope of accreditation.”[3]
So if a report carries an asterisk note like that, the marked tests sit outside the accreditation. That disclosure is what ILAC-P8 asks for, and it means those values are not covered by the scope of accreditation. Ask which tests are marked, and why.
The method, limit and number for a test
ICH Q7 says: “The certificate should list each test performed in accordance with compendial or customer requirements, including the acceptance limits,” and the numerical values obtained.[5] A line that says only “Pass” or “Conforms,” with no limit and no number, leaves you unable to check the call.
Units belong to the number. FDA’s data integrity guidance gives the plainest example: “the number ‘23’ is meaningless without metadata, such as an indication of the unit ‘mg.’”[8]
Lot, dates and signature
A certificate describes one sample from one lot. ICH Q7 expects “authentic certificates of analysis” for each batch, with the batch number on the certificate.[5] It also says: “Certificates should be dated and signed by authorized personnel of the quality unit(s).”[5] The ISO/IEC 17025 clause, per NIST, lists receipt and issue dates and who authorized the report.[4]
Ask: does the lot on the certificate match the material? Who signed it?
Re-issued certificates
ICH Q7 says that when a certificate is re-issued by a repacker, agent or broker, it should show the name and address of the laboratory that performed the analysis and refer to the original batch certificate.[5] If a certificate shows a seller’s name but no testing lab, ask for the lab’s original report.
Purity, identity and content are separate lines
HPLC purity is “the percentage of requested peptide in relation to the total amount of material absorbing at 220 nm,” per a peptide manufacturer’s FAQ (a secondary source).[10] It is not the peptide’s share of the powder: “NPC and purity are not equivalent, because the former includes peptidic contaminants.”[11] Identity is a third question; a peptide manufacturer’s guide lists mass spectrometry, which determines the molecular weight, among its identity tests.[11] See HPLC and how to read a chromatogram, Mass spectrometry: identity, not purity and How net peptide content is measured. For a counterion line, see TFA, acetate or chloride; for an endotoxin line, Endotoxin testing for peptides.
Questions people ask
What does ISO/IEC 17025 accreditation mean for a testing lab, and does it cover the whole of its work?
It means an accreditation body has evaluated the lab against ISO/IEC 17025 for specific activities.[1] It covers only the activities in the lab’s scope of accreditation, not everything the lab does.[2]
How do I check a lab’s accreditation scope instead of trusting a logo?
Confirm the accreditation body is an ILAC signatory, then find the lab’s scope in that body’s directory and look for the test method.[6][7]
What should a certificate of analysis list for a test?
The method, the acceptance limit and the numerical value, with units.[4][5]
Why do the lot number and dates on a certificate matter?
The certificate describes one batch.[5] The lot ties the report to the material in hand; the dates show when the sample was received and reported.[4]
What is the difference between HPLC purity and a mass spectrometry identity check?
HPLC purity is the requested peptide’s share of the material that absorbs at 220 nm.[10] It is not an identity check, and it is not the peptide’s share of the powder.[11] Mass spectrometry determines the molecular weight, which is an identity check.[11]
What does it mean when a report says some tests are outside the lab’s accreditation scope?
The marked tests are not covered by the scope of accreditation. ILAC-P8 requires reports to make that clear rather than imply coverage.[3]
Sources (fetched October 13, 2026)
- ILAC, “About ILAC.” https://ilac.org/about-ilac/ (fetched October 13, 2026)
- ILAC-G18:04/2010, Guideline for the Formulation of Scopes of Accreditation for Laboratories. https://european-accreditation.org/wp-content/uploads/2018/10/ILAC_G18_04_2010.pdf (fetched October 13, 2026)
- ILAC-P8:11/2023, Supplementary Requirements for the Use of Accreditation Symbols and for Claims of Accreditation Status by Accredited Conformity Assessment Bodies. https://ilac.org/?ddownload=125463 (fetched October 13, 2026)
- NIST, ISO/IEC 17025:2017 crosswalk for clause 7.8, on reports. A secondary summary of the standard. https://www.nist.gov/document/7-8-17025-crosswalk-reporting-results-20180201pdf (fetched October 13, 2026)
- FDA, ICH Q7 Good Manufacturing Practice Guidance for Active Pharmaceutical Ingredients, section 11.4, Certificates of Analysis. https://www.fda.gov/media/71518/download (fetched October 13, 2026)
- U.S. Nuclear Regulatory Commission, procurement note on ISO/IEC 17025 accredited services, ML14153A126. https://www.nrc.gov/docs/ML1415/ML14153A126.pdf (fetched October 13, 2026)
- ILAC, “ILAC MRA and Signatories.” https://ilac.org/ilac-mra-and-signatories/ (fetched October 13, 2026)
- FDA, Data Integrity and Compliance With Drug CGMP: Questions and Answers. https://www.fda.gov/media/119267/download (fetched October 13, 2026)
- A2LA, public documents list, including P112, Policy on Flexible Scopes. https://portal.a2la.org/documents/ (fetched October 13, 2026)
- Bachem, “What does net peptide content mean?” Manufacturer FAQ; a secondary source. https://www.bachem.com/helpie_faq/what-does-net-peptide-content-mean/ (fetched October 13, 2026)
- Bachem, “Quality Control of Amino Acids & Peptides: A Guide.” Manufacturer guide; a secondary source. https://www.bachem.com/knowledge-center/quality-control-of-amino-acids-peptides-a-guide/ (fetched October 13, 2026)