How it works
As a sample passes through the HPLC column, its components emerge at different times and reach the detector one after another. The detector records signal against time, and each emerging component registers as a peak at its characteristic retention time.
The area under a peak is proportional to how much of that component reached the detector. Purity is computed from those areas — the target peak’s area as a share of the total integrated area — so the chromatogram is not just a picture but the thing the purity number is derived from.
Shape carries information the single number omits. A sharp, symmetric, baseline-resolved main peak reads differently from one with a shoulder or a tail, even at the same reported percentage. Reading the trace, not only the figure, is what distinguishes a clean preparation.
Why it matters
The chromatogram is the evidence behind the purity claim. A percentage asserts a result; the trace shows the separation that produced it, including whether an impurity sits just under the reporting threshold.
Because peaks are placed in time by the method, a chromatogram is only interpretable alongside the method that produced it — the same sample on a different gradient gives a different-looking trace.
It also records what the method could not see: anything that co-elutes with the target or does not absorb at the detection wavelength leaves no peak, a limit the picture makes concrete.
A percentage asserts a result; the trace shows the separation that produced it.
At Lineará
On the certificates, purity is reported as an RP-HPLC area percentage — the number a chromatogram yields — alongside the method used to produce it.
The chromatogram images in the certificate library are illustrative placeholders, labeled as such; the renderer prefers real trace data wherever it has been supplied.