TSCA Definition 2019: The complex residuum from the distillation of C5 to C8 by-products from the Houdry butadiene production. It consists predominantly of hydrocarbons having carbon numbers predominantly in the range of C5 through C9 and boiling in the range of approximately 240.degree.C to 450.degree.C (464.degree.F to 842.degree.F).

TSCA Definition 2019: A complex combination of hydrocarbons produced during isoprene purification. It consists predominantly of unsaturated C5 hydrocarbons.

TSCA Definition 2019: The complex combination of hydrocarbons obtained from a benzene recovery unit. It consists of hydrocarbons having carbon numbers predominantly in the range of C6 through C12 and boiling in the range of approximately 65.degree.C to 230.degree.C (149.degree.F to 446.degree.F). This stream may contain 3 vol. % or more benzene.