Quality Control
Reference Standard
Research use only. For in vitro research use only. Not for human or animal consumption. Not for human consumption, medical use, or personal application.
A reference standard is a material of established identity and known content used to make another measurement meaningful. It is what lets a retention time be assigned or a result expressed as a quantity rather than an area. If its assigned value is wrong, every sample quantified against it is wrong by the same factor, and the chromatogram looks normal.
Errors from a standard are systematic, not scattered
A standard arrives with an assigned value, a re-test date and storage conditions, all load-bearing. One held outside them may have degraded and will still give a clean peak — just a smaller response, shifting every result the same way.
Where no qualified standard exists for a sequence, quantification is relative rather than absolute. That is the ordinary case for research peptides, and one reason purity is reported as area-percent: area needs no external standard.
Qualified standard, working standard, retained sample
Three different things. A qualified standard carries an assigned value traceable to a documented characterisation. A working standard is ordinary material characterised against it to conserve it. A retained sample has no assigned value.
Conflating them weakens a qualification file. A retained vial can answer whether a new lot resembles the last; it cannot support a content claim. Record which was used, alongside the lot's Certificate of Analysis.
Frequently asked questions
- Is a supplier's certificate a substitute for a reference standard?
No. A certificate reports what a supplier's laboratory measured on one lot; a standard is material run alongside your own samples. No certificate calibrates your HPLC method.
- Can catalogue material be used as a standard?
Only with characterisation of its own. Research-grade material is supplied against a lot certificate, not with an assigned content value, so using it as a working standard means establishing that value yourself.
- If mass is measured, why is a standard still needed for identity?
Mass narrows the possibilities without always resolving them: isomers, and sequences of the same composition in a different order, share a mass. Co-elution with a characterised standard separates them.
Updated 2026-06-01