HPLC Purity Testing: What “99%+” Actually Means

HPLC, or high-performance liquid chromatography, is the standard method for measuring the purity of synthetic compounds. When a report says “99%+”, HPLC is almost always where that number comes from.

How it works

A small, dissolved sample is pushed under high pressure through a column packed with fine particles. Different molecules travel through the column at different speeds, so they leave it at different times. A detector at the end records each one as a peak on a chart called a chromatogram.

Reading the chromatogram

In a clean sample, one large peak dominates the chart. Smaller peaks represent related substances, such as incomplete sequences or by-products of synthesis. Purity is calculated by dividing the area of the main peak by the total area of all peaks.

What the number does and does not tell you

• It tells you how much of the detected material is the target compound.
• It does not, on its own, confirm identity. That is the job of mass spectrometry.
• It does not measure bacterial endotoxins, which need a separate test.

Why independent testing matters

A purity figure is only as trustworthy as the lab that produced it. Reports from an independent, third-party laboratory, with a verification link you can open yourself, carry far more weight than an in-house claim.

You can see the chromatograms and reports for each current batch on our Lab Results page.

For laboratory research use only. Not for human or animal consumption.