OES (Optical Emission Spectrometry)
Spark-based lab technique excellent for C, S, P in steel — complements portable XRF.
Optical Emission Spectrometry (OES) uses an electric spark to vaporize a tiny area of metal and measures light emitted by excited atoms. It excels at low-level carbon, sulfur, and phosphorus in steel — elements that portable XRF cannot reliably quantify.
Best practice: use portable XRF for field PMI screening and OES for lab certification on critical samples. See our XRF vs OES comparison in the Knowledge Center.