DOT requires samples with volatile organic compounds to be shipped with free headspace while EPA requires containers holding volatile organic compounds to not have free headspace. DOT clarified the requirements, saying that if the vial containing volatile organic compounds is placed in a larger container with free headspace, both EPA and DOT requirements will be satisfied.
You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.- Department of Transportation (DOT) Letter Regarding the Inconsistency Between EPA and DOT Requirements for Headspace in Volatile Organic Samples (PDF)(1 pg, 2 MB, December 4, 2000, 00-308)