This test method covers a procedure to test membrane filters for their ability to retain bacteria whose diameter is equal to or slightly larger than the 0.2-μm pore size of the membrane filter.

Formerly under the jurisdiction of Committee D19 on Water, this test method was withdrawn in July 2010 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.

Microbiological water testing procedures using membrane filtration are based on the premise that all bacteria within a specific size range will be retained by the membrane filter used. If the membrane filter does not retain these bacteria, false negative results or lowered density estimates may occur that could have serious repercussions due to the presence of unrecognized potential health hazards in the water being tested, especially in drinking water.

5.1.1 This procedure as devised will enable the user to test each membrane filter lot number for its ability to retain all bacterial equal to, or larger than, the stated membrane pore size.

Since this membrane is often used to sterilize nonautoclavable liquids, it is essential that the retention characteristics of this membrane are stable.

1.1 This test method covers a procedure to test membrane filters for their ability to retain bacteria whose diameter is equal to or slightly larger than the 0.2-µm pore size of the membrane filter.

1.2 The procedures described are for the use of user laboratories as differentiated from manufacturers' laboratories.

1.3 This standard does not purport to address the safety problems 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.