Refiners and importers may not use the 100% independent lab analysis option for certain parameters and the 10% independent lab analysis option for other parameters, but must use the same option for all RFG parameters.

However, a refiner or importer using the 10% independent analysis option may use another lab, including the refiner's or importer's designated independent lab, to perform analyses that are the responsibility of the refiner or importer provided the substitute lab properly performs the testing. In any case where a refiner or importer uses a substitute lab, the refiner or importer remains responsible for the proper conduct of the analyses, and for meeting all requirements for reporting test results to EPA.(7/1/94)

This question and answer was posted at Consolidated List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (PDF)(333 pp, 18.17 MB, EPA420-R-03-009, July 2003, About PDF)