Environmental regulations set the maximum permitted sulfur level in car fuels at 10 mg/kg. Several different X-ray fluorescence technology test methods are available for analyzing the sulfur concentration, for example, ASTM D4294 (EDXRF) and ASTM D2622 (WDXRF). The environmental Protection Agency (EPA) Tier 3 regulation introduced in 2017, is XRF technology independent, with the condition that the performance of the instrument meets the Tier 3 accuracy and precision requirements.

This application note shows that Epsilon 4 complies with the Tier 3 requirements in only five minutes measuring time.