--- title: "Testing methodology: how a Sable CoA is produced and what it covers | Sable Peptides" description: "How each lot is tested (HPLC purity, mass-spectrometry identity), what a certificate of analysis covers and does not cover, how to verify a lot at /lot-lookup, and what is published versus sent on request. Research use only." canonical: https://www.sablepeptides.co.uk/testing-methodology publisher: Sable Peptides Limited (UK company 17488610) note: Research use only. Not for human or veterinary use. --- # Testing methodology This page explains, plainly, how a certificate of analysis (CoA) for a Sable lot is produced, what it tells you, what it does not, and how to check the lot you hold. It names no laboratory and quotes no lab values: those are on the CoA for your lot, which you can request. ## The release rule Peptides in this catalogue are released at ≥99% purity by HPLC, with identity confirmed against the expected mass. Every vial is marked with its lot number. This is a batch-release specification, not a licensed-medicine standard and not a guarantee of fitness for any biological use. The lot number and the certificate are not printed on the product page. Both can be requested. ## What is tested for each lot - **Purity by HPLC.** Reverse-phase high-performance liquid chromatography separates the sample into peaks, detected by UV absorbance. Purity is the main peak's area as a percentage of all detected peak area. The CoA should show the chromatogram, not only the number. [How to read an HPLC chromatogram](/learn/how-to-read-an-hplc-chromatogram). - **Identity by mass spectrometry.** The observed molecular mass is compared with the theoretical mass of the expected sequence or structure. A match confirms the molecule has the right mass. - **Lot traceability.** The lot number on the CoA is the lot number printed on the vial label. A certificate applies to that lot only. ## Limitations: what a purity and identity CoA does not show - **HPLC purity is not peptide content.** A lyophilised peptide also contains counter-ions (for example trifluoroacetate or acetate salts from purification) and residual water. HPLC area-% ignores these, so a 99% pure sample can hold noticeably less than its label weight as free peptide. Net peptide content is a separate test. [Purity vs peptide content](/learn/purity-vs-peptide-content). - **UV detection only sees what absorbs.** Impurities that do not absorb at the detection wavelength, or that co-elute with the main peak, are not separated out. - **Mass identity is not full sequence proof.** Mass spectrometry confirms total mass. Isomers or residues swapped in order can share a mass; sequencing (for example MS/MS) is a different analysis. - **Not covered unless the CoA lists them:** endotoxin, sterility or bioburden, residual solvents, heavy metals, counter-ion and water content, and stability over time. If your protocol needs any of these, check whether the certificate you receive lists the test before relying on it. - **A CoA is a batch document.** It describes the lot at the time of testing. It is not a regulatory approval, not a medicinal-product standard and not a guarantee of fitness for any biological use. Background on those tests: [endotoxin testing (LAL and rFC)](/guides/endotoxin-testing-for-research-peptides), [sterility vs endotoxin vs bioburden](/guides/sterility-vs-endotoxin-vs-bioburden), [amino acid analysis](/guides/amino-acid-analysis-for-peptide-content), [measuring residual TFA](/guides/measuring-residual-tfa-in-peptides), [water content by Karl Fischer](/guides/water-content-karl-fischer-on-peptide-coas), [elemental impurities (ICH Q3D)](/guides/elemental-impurities-ich-q3d-and-peptides), [method validation terms (ICH Q2)](/guides/analytical-method-validation-terms-on-a-coa), [ISO/IEC 17025 accreditation](/guides/iso-17025-accreditation-for-peptide-testing-labs). Reading results: [HPLC system suitability](/guides/hplc-system-suitability-explained), [MS/MS b and y ions](/guides/tandem-ms-b-and-y-ions-explained), [area % vs weight % vs assay](/guides/area-percent-vs-weight-percent-vs-assay), [measurement uncertainty](/guides/measurement-uncertainty-in-peptide-purity-results), [out-of-specification results](/guides/out-of-specification-results-explained), [peak integration rules](/guides/chromatographic-peak-integration-rules), [mass accuracy and isotope patterns](/guides/high-resolution-ms-mass-accuracy-and-isotope-patterns), [sending a sample for independent testing](/guides/sending-a-peptide-sample-for-independent-testing). ## How to verify your lot 1. Read the lot number on your vial label. 2. Enter it at [/lot-lookup](/lot-lookup). 3. If the lot is not listed online, request its CoA at [/coa-request](/coa-request). It is emailed within 2 hours. 4. On the CoA, check: compound name and stated amount; lot number matching the vial character for character; the HPLC purity with its chromatogram; observed versus theoretical mass; the test date. [How to verify a CoA](/learn/how-to-verify-a-coa). ## Published versus on request - **Published:** the release rule above, this methodology, compound identity data (sequence, formula, molecular weight, CAS where verified) on each reference page, and the CoA library, which lists lots only once the lab document is posted (none are posted yet). - **On request:** the CoA for any lot, emailed within 2 hours to the person who asks. Certificates are not posted as a public image gallery because images can be copied, edited or quoted out of context. Research use only. Not a medicine. Not for human or veterinary use. See the [disclaimer](/disclaimer), [quality](/quality) and the [catalogue](/catalogue).