A Purity Percentage Is Not a Passport: Why Identity Testing Belongs in Every Laboratory SOP
When a laboratory SOP is being revised, the purity figure is usually the first number under scrutiny. That is understandable: a percentage is easy to tabulate, compare and place in an acceptance box. But a purity percentage answers a narrower question than many teams assume. It describes the analytical result reported for a batch; it does not, on its own, confirm that the material in the vial is the compound named on the label. For researchers and materials managers updating documentation, identity testing must remain a separate, visible and mandatory criterion beside purity. The point is not to distrust one test but to stop a single number doing two jobs.
Why a Purity Percentage Cannot Carry the Whole Quality Decision
Purity is typically expressed as a percentage from an analytical method such as HPLC, with the result recorded on the certificate of analysis (CoA). The Research Sciences FAQ states that peptides are typically supplied at ≥99% purity (HPLC tested) and that the exact purity is stated on the CoA; the homepage at the time of writing also lists a ≥99% Verified Purity line and CoAs Janoshik Analytical Reports. Those are published site claims, not independent audit findings, so they should be reconfirmed on the live site and, more importantly, checked against the batch CoA that accompanies the material. A purity percentage can be high while the identity entry is missing, ambiguous or linked to the wrong batch. The SOP should therefore require both fields to be reviewed and recorded, with identity treated as the evidence that the material matches the intended research compound. A chromatographic purity result can show a dominant main peak, but it does not by itself establish molecular identity. Purity and identity answer different questions: how much of the detected material is represented by the main peak, and how the material is characterised as the expected compound. When an SOP uses a single threshold, a reviewer can sign off a CoA because the purity figure is visible while the identity field remains unchecked against the label, study file and receiving record. That is an administrative risk, not a theoretical one. A high percentage travels neatly through spreadsheets; identity evidence often sits in a separate field or method note. If the SOP does not force the reviewer to look, it can be skipped. Materials managers should also avoid treating cap colour, packaging style or a general website statement as identity evidence. Identity and purity belong in separate acceptance lines because they serve separate quality decisions.
What Identity Testing Adds to the SOP Review
Identity testing is the part of the record that ties the result to the intended research material. It should prompt the reviewer to ask not only “what was the purity?” but “what was identified, by what reported method, and on which batch?” The CoA should be read as a batch document, not as a general marketing page. Research Sciences describes an expanded testing framework that evaluates submitted samples for purity, identity, heavy metals and endotoxin, and says CoAs are linked to supported products. That is useful context, but the SOP should require the reviewer to open the CoA that accompanies the specific batch and check the identity entry against the label, study file and receiving record. Heavy-metal and endotoxin screening can add valuable contaminant information, yet they do not replace the identity field; they answer different questions. Likewise, a high purity percentage is not a substitute for checking that the identity result matches the expected compound. For laboratories sourcing Uk peptides, the practical check is whether the batch CoA can be retrieved by the label reference and whether the identity entry is legible and consistent. Research Sciences notes that restocks can share an Internal Test Reference (ITR) with earlier stock. The ITR points to associated sample testing reports; it does not establish that separate deliveries come from the same production lot or have been independently tested as separate lots. The SOP should therefore prevent an ITR from being treated as a lot number. Packaging variation, including cap colour, should never be used as an identity check; cap colour should not be read as evidence of identity, analytical quality or manufacturing origin. All materials are strictly for controlled laboratory and analytical research, are research-use-only, and are not for human or veterinary use.
Turning the Principle into a Practical SOP Update
An SOP update is strongest when identity and purity appear as two required columns, not one combined “quality” tick. A practical revision can start with a documentation gate: before material enters an in-vitro study, match the label reference, such as the SKU code and expiry format illustrated by BPC10-03/27, to the batch CoA, then record the compound, batch or ITR context, identity result or reported identity entry, and purity result. Keep an explicit note that an ITR is a testing-reference link, not an automatic production-lot identifier. The acceptance criteria should be separate. The purity criterion should come from the laboratory’s own validation or from the CoA statement, with the source written into the SOP; the identity criterion should require a match to the intended compound as documented on the batch CoA. Do not copy a threshold from a marketing headline. At receipt, record condition, storage location and label details, but do not use cap colour as an identity check. Store lyophilised materials at −20°C or below, sealed with desiccant and protected from moisture, heat and light; avoid repeated freeze–thaw cycles. For in-vitro reconstitution, allow the vial and solvent to reach ambient temperature before opening, work in a clean environment, remove only the amount required for the assay, and record diluent volume and concentration for the experimental workflow. Reconstituted material is less stable and should be held at 2–8°C for short-term laboratory use. The Research Sciences reconstitution calculator and materials are for laboratory research only and must not be used for human or veterinary dosing. These materials are not medicines, medical devices, injectables, treatments or food supplements under UK law and are not for human or veterinary use. The SOP should also state that the purchaser remains responsible for lawful use, safe handling, storage, disposal and COSHH compliance, and for checking suitability for the intended research application. Materials managers should reconcile purchase order, label reference, batch CoA and study file, and review the SOP whenever a restock, CoA format change or packaging variation appears. Research Sciences publishes lines such as “3,000+ UK Orders”, “24hr UK Delivery”, “7 Days Expert Customer Support” and “CoAs Janoshik Analytical Reports”; treat them as current site wording to reconfirm, not as batch-level evidence. Delivery times are estimates and may vary, so the SOP should rely on the batch CoA and receiving record rather than a headline promise. The SOP should keep identity testing beside the purity percentage, with neither allowed to stand in for the other.
Santorini dive instructor who swapped fins for pen in Reykjavík. Nikos covers geothermal startups, Greek street food nostalgia, and Norse saga adaptations. He bottles home-brewed retsina with volcanic minerals and swims in sub-zero lagoons for “research.”
