Reference standard

A reference standard is an authenticated sample of a compound that a laboratory runs alongside a test sample to confirm the sample's identity.

In a retention-time match, written HPLC-RTM on some certificates, the laboratory runs an authenticated reference standard of the compound under the same conditions as the sample and checks that the main peaks come off the column at the same time. Agreement is evidence that the sample's main compound is the same molecule as the standard.

It is one of the two common routes to identity, the other being mass spectrometry. The two answer the question differently: mass spectrometry checks that the molecule weighs what the sequence predicts, while a retention-time match checks that it behaves like a known, verified sample of the real compound.

A retention-time match is only as good as the reference standard behind it, and two different molecules can occasionally elute together, so laboratories that need certainty combine methods. Of the laboratories named on Aion's certificates, ILS Laboratories is the one that reports identity against a reference standard; see the testing page for what each certificate reports.

Related terms

• High-performance liquid chromatography
• Mass spectrometry

UPDATED OCTOBER 26, 2026 · REVIEWED BY DEL POTTER, PHD