ASTM PS74-98

1.1 These provisional test methods cover the measurement of oil and grease in water and wastewater by a gravimetric determination of solvent extractable substances from an acidified sample. Also included in this measurement of oil and grease are any other compounds soluble in the organic solvent (n-hexane) and nonvolatile under the conditions of the test. Two methods of solvent extraction are provided: Provisional Test Method A-Liquid-Liquid Extraction (Sections 8-15); and Provisional Test Method B-Soxhlet Extraction (Sections 16-23).

1.2 These provisional test methods are applicable to natural waters and domestic wastewaters. They are also suitable for most industrial wastewaters, although certain wastes may yield low results because of the presence of either excessive concentrations of natural greases or synthetic or modified compounds that are not well recovered by these provisional test methods. The applicable concentration range for oil and grease is from 4 to 100 mg/L for Provisional Test Method A and 20 to 200 mg/L for Provisional Test Method B.

Note 1- A new range is to be provided when round robin data is available. Values are based on the measurement of hexadecane.

1.3 These provisional test methods measure those groups of substance called oil and grease, whether soluble or insoluble, polar or nonpolar, or biological or mineral in origin, to the extent these substances partition from the matrix into the organic extraction solvent and are not volatilized under conditions of the test. See also the Introduction and 3.2.1.

1.4 Results using one extraction solvent, for example, n-hexane, are not usually comparable to results using another extraction solvent, for example, diethyl ether or tetrachlorethene, or 1,1,2-trichloro-1,2,2-trifluoroethane, even when the same provisional test method is otherwise followed exactly. The extraction solvent used is therefore reported with results.

1.5 Because these provisional test methods include an acidification step prior to extraction, soluble metallic soaps are hydrolyzed and recovered as fatty acids in the extraction step.

Note 2-Refer to companion procedures Test Methods D3921 and D4281.

1.6 This provisional standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see 7, 13.2, 13.10, 21.2, 21.6, and 21.7.

1.7 Provisional standards achieve limited consensus through approval of the sponsoring subcommittee.