AssayIndex
Mass spectrometry

ppm

Parts per million. Used for mass accuracy: ppm = (observed − theoretical)/theoretical × 10⁶.

Related terms

Mass accuracy
Difference between measured and theoretical mass, in ppm of the theoretical value. A relative measure — the same ppm is a different absolute error at different masses.
see also ppm · Rule AX-R01

Where this term appears

The glossary exists to make record pages readable without a chemistry degree. Every technical term on a report resolves here.