Generally, the results from the composite sample, tested using the methods specified in § 80.46 of the regulations, should be used. If more than one composite sample is taken during the blend and tested to determine compliance, or if the composite is tested more than once, an average of the test results must be used. The number of composite samples taken and the number of tests conducted on each sample should be the same for each batch (i.e., a refiner should specify in his petition how many analyses will be performed on a composite sample and must conduct the same number of tests on all batches produced). Data and test results from component tanks, on-line samples and spot samples would be used to control the blend properties and to corroborate composite sample results.

EPA will evaluate, on a case-by-case basis, proposals for using results from on-line analyzers or storage tank samples for certification of fuel properties, based on the particular equipment being used on-line and other relevant aspects of the particular in-line operation. Spot sample results cannot be used for certification, but are appropriate quality control/quality assurance measures to check and correlate the on-line analyses and/or composite results.(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)