Research notes
Identity confirmation by mass spectrometry
Aug 4, 2026 · 5 min read
Purity and identity are different questions
HPLC purity answers a quantitative question: of everything detected, what fraction is the main component? It says nothing about whether that main component is the compound named on the label.
Identity is a qualitative question, and it is answered by mass spectrometry. The measured molecular weight of the main peak is compared against the theoretical molecular weight of the target sequence. A match confirms the material is what it claims to be; a mismatch means it is not, regardless of how pure it is.
Why both are the minimum
A sample can be 99% pure and entirely the wrong compound. Conversely, a correct identity with poor purity means the vial contains the target material diluted by synthesis by-products.
For material entering our stock, both analyses are required on the same batch: chromatographic purity under a stated method, and mass-spectrometric identity confirmation against the theoretical sequence weight. One without the other is an incomplete record.
Reading the mass spec section of a certificate
Look for the theoretical and observed molecular weights side by side, the instrument type, and the ionisation mode. The observed value should match the theoretical value within the instrument's stated tolerance.
Our certificates print both values for every batch, so the identity check can be verified independently rather than taken on trust.
This note describes analytical documentation only. Materials supplied by Basic Tides are for in-vitro laboratory research only — nothing here is guidance for use in humans or animals. For the underlying framework, see our research standards.