Currently, the EPA's GC/MS method for aromatics does not work (poor repeatability precision on successive sample injections.) Should refiners spend $100,000 each for GC/MS instruments before the EPA method development work is complete? What is the likelihood of the EPA later rejecting the GC/MS method altogether?
When EPA developed the GC/MS method for the determination of aromatics in gasoline, samples that were run side by side after the method was completed showed that the precision of GC/MS was considerably better than D-1319. This study was undertaken several years ago, and involved some thirty or so samples, all analyzed without any change to the calibration.
Currently, ASTM is in the round robin phase of development of their version of the GC/MS method. The details of this method have been coordinated with EPA, and we believe they are consistent with the regulatory requirements. Evaluations of the need for the use of secondary and tertiary ions for compound identification during this round robin will provide EPA with some hard evidence for evaluating whether this technique will be permitted. Should secondary and tertiary ion use prove unnecessary, it is possible that instruments costing about $35K will be suitable.
In any case, as discussed above, the regulations provide an optional alternate method until 1/1/97. After that time, the GC/MS analysis for aromatics will be the only allowed method for this property. Should the ASTM GC-MS method prove satisfactory, EPA will accept its use. (7/1/94)
This question and answer was posted at List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (pdf)