Ill. Admin. Code tit. 35 § 729.220
As used in this Subpart, terms have the following meanings:
Aqueous phase: A "phase" in which water is the solvent, constituting more than 500 g/kg.
Component: An element or compound present in a "phase" or "system".
Emulsion: A "system", including two or more liquid "phases", which is not separated into layers. For purposes of this Subpart, an emulsion which does not form layers within one hour is one phase.
Liquid: A waste, or part of a waste, which yields any fluid when subjected to the paint filter test described in Section 729.320.
Non-aqueous phase: A "phase" which contains 500 g/kg or less of water.
One-phase system: A "system" with one and only one "phase".
Phase: A physically distinct portion of a dispersion or solution which at least in principle could be mechanically separated from the remainder of the material. For purposes of this Subpart, a container is not a phase, nor is a vapor above a waste. Emulsions and suspensions are a single phase if they do not form layers within one hour.
Solid: A waste, or part of a waste, which contains no free liquid as determined from the paint filter test described in Section 729.320.
Suspension: A "system", including a "solid" phase and a "liquid" phase, which is not separated into layers. For purposes of this Subpart, a suspension which does not form layers within one hour is one phase.
System: A single isolated "phase" or a set of two or more "phases" which are in physical contact.
TOX test: Either of the tests for total organic halogen incorporated by reference in Section 729.202, ASTM D2361-66 (Reapproved 1978) or ASTM E442-74 (Reapproved 1981).
Two-phase system: A "system" with two "phases".
Ill. Admin. Code tit. 35, § 729.220