Testing the Limits

We are at the dawn of the new age of sulphur limits in automotive fuels. So-called zero sulphur fuels (less than 10 mg/kg) were first available in the European Union in 2005 and will be mandatory by 2009. In the USA during 2006 there will be a nationwide transition of most diesel fuel from low sulphur to ultra low sulphur (ULS) diesel (less than 15 mg/kg) as a precursor to new 2007 diesel engines and vehicles. New stringent fuel specifications result in a need for improved testing methods and this article updates a previous one, “Chasing the Limits” from February/March 2004. That article described how the new Oxford Instruments Twin-XULS sulphur analyser with a Low Background Proportional Counter has low spectral background giving the improved limit of detection necessary to measure accurately the new low sulphur limits. Since then the new technology has become the only bench-top XRF technique possessing all three of an Energy Institute IP method, an ASTM method and a performance statement from the United States Environmental Protection Agency (USEPA). Thus, bench-top EDXRF retains its reputation of being "the most cost effective, simplest, and most reliable method of doing product release 24 hours a day".