RESEARCH LIBRARY
HPLC and LC-MS Explained
HPLC and LC-MS appear in many analytical reports. Their names describe analytical techniques; the report’s method and results explain what a particular test actually established.
This guide explains those techniques in general. It does not confirm which tests have been performed on an Astra Biolabs batch.
What is HPLC?
High-performance liquid chromatography separates components as a liquid mobile phase passes through a chromatographic system. A detector records a response as components elute. The resulting chromatogram shows peaks over time.
A chromatogram is interpreted under specified conditions. Separation, detector response, and peak integration affect what can be concluded. A single prominent peak is not a complete description of every substance present.
What does LC-MS add?
Liquid chromatography–mass spectrometry combines liquid-phase separation with mass-spectrometric detection. This provides mass-related information about the detected components, complementing the separation.
When reviewing an identity claim, look for the laboratory’s stated identity method and conclusion. Merely seeing “LC-MS” on a page does not tell you whether an identity assessment was performed or whether its acceptance criteria were met.
Purity, identity, and assay answer different questions
- Identity: Does the analytical evidence support the stated identity of the material?
- Chromatographic purity: How is the measured chromatographic response distributed among the peaks included by the method?
- Assay or content: How much of the specified substance does the validated quantitative method find?
These results should not be substituted for one another. An HPLC assay may compare responses against controls or standards; its calculation and units differ from a simple peak-area percentage.
A peak-area percentage is not automatically a mass percentage
Illustrative example: If a designated peak contributes 990 response units and the total included peak area is 1,000 units, its normalized area is 99%. This arithmetic describes the included detector response. It does not, by itself, establish the total material’s mass composition or the amount in a container.
Interpretation depends on the method and detector, which peaks are resolved and included, and whether different components have comparable responses. WHO chromatography guidance emphasizes sound, consistent integration and documented treatment of unresolved peaks.
What to ask when reviewing a result
- What is the method identifier and detector?
- Is the result an identity assessment, area percentage, or quantitative assay?
- What reference standard and acceptance criteria apply?
- Are the chromatogram and integration details available for review?
Neither an HPLC nor an LC-MS result alone establishes sterility or suitability for human use. Read results alongside their documented scope and the research-use policy.
Continue with How to Read a Certificate of Analysis, or return to the Research Library.