What it means for a research store
When a COA says “purity 99.1% (HPLC)”, it usually means that under that method the main peak accounted for 99.1% of the total detected peak area. The number depends on the method: the column, the detector wavelength and how the laboratory integrated the peaks. Two laboratories can report different purities for the same lot and both be correct for their methods.
Purity is not the same as content or identity. A sample can show a high chromatographic purity and still contain water, salts or counter-ions that the method does not measure, and a purity figure says nothing about identity unless it is paired with an identity test such as mass spectrometry. This is why a single “99%+” badge on a product card is weaker evidence than the report itself.
For stores, the safest practice is to quote purity exactly as reported for a named lot, with the method, and to link the report. Avoid rounding up, avoid applying one lot’s figure to the product in general, and avoid turning a purity figure into a claim about what the material does.
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Updated September 25, 2026. General information for merchants, not legal, tax or financial advice. This glossary does not describe the use of any compound in people.
