Research Library
Understanding HPLC purity testing
How HPLC purity figures are produced, what they represent and the limits of a single percentage figure.
How it works
In HPLC, a dissolved sample is pumped through a column packed with a stationary phase. Different components travel through the column at different rates and are detected as they leave it, producing a chromatogram of peaks.
What the percentage means
Purity is commonly reported as the area of the main peak divided by the total area of all detected peaks. It reflects what the detector can see under the chosen conditions, so the method, wavelength and column all affect the figure.
Limitations
HPLC purity alone does not confirm identity. It is usually paired with mass spectrometry, which confirms that the main peak has the expected molecular mass.