Two claims that should not be collapsed
A statement such as “99% HPLC” is not a complete description of an analytical result. It should be accompanied by a method and a clear definition of the percentage. An amount such as milligrams per vial needs its own quantitative basis.
The distinction is built into analytical validation: identity, purity/impurities and assay are different intended purposes. A report may address one, several or none of them adequately. A compact badge can hide those differences, so read the report rather than the headline.
ICH Q2(R2): analytical validation by intended purpose
Follow the units all the way through
Before comparing numbers, ask what the denominator represents. Percentage chromatographic area, mass fraction, total dry mass and analyte-equivalent content are not interchangeable labels. Salt form, counterions, water and the exact material definition can change the basis of a mass statement.
When a report and product specification use different bases, ask the issuer to explain the conversion instead of calculating a confident verdict from incompatible inputs. The same discipline applies when comparing two suppliers.
ICH Q2(R2): analytical validation by intended purpose
A worked arithmetic example, not a quality verdict
If a label declares 10 units of an analyte and a compatible assay reports 9 units, the entered assay is 10% below the entered nominal value. This is arithmetic only. Whether that result meets a specification depends on the agreed limits, analytical uncertainty and an equivalent measurement basis.
Our CoA checklist can calculate that relative difference. It does not choose a universal acceptance limit or authenticate a report. A matching number is not proof of every other quality attribute.
What to ask for next
Request a lot-specific report that names the measured attribute, units, method and issuer. If you need an amount, ask for an appropriate quantitative result rather than assuming an area percentage supplies it. If you need identity, check the evidence supporting the assignment.
Document what remains unmeasured. Manufacturing origin, long-term stability and suitability for a particular application are separate questions. A transparent gap is more useful than an unsupported all-purpose quality score.
ICH Q2(R2): analytical validation by intended purpose
Questions, answered.
Does 99% purity mean a vial contains 99% of its labeled amount?
No. Purity and label quantity are separate claims unless a report explicitly defines and validates a relationship between them.
Can high purity establish sterility?
A reported chromatographic purity result does not substitute for a separately specified sterility assessment.
What does the CoA checklist calculate?
It compares the reported and nominal content values entered on the same basis, checks completeness, and flags entered lot mismatches. It makes no release or safety decision.