Standard Practice for Extraction of Materials Used in Medical Devices
5.1 These extraction procedures are the initial part of several test procedures used in the biocompatibility screening of plastics or other materials used in medical devices.
5.2 The limitations of the results obtained from this practice should be recognized. The choices of the extraction vehicle, duration of immersion, and temperature of the test are necessarily arbitrary. The specification of these conditions provides a basis for standardization and serves as a guide to investigators wishing to compare the relative resistance of various plastics or other materials to extraction vehicles.
5.3 Correlation of test results with the actual performance or serviceability of materials is necessarily dependent upon the similarity between the testing and end-use conditions (see 12.1.2 and Note 7).
5.4 Caution should be exercised in the understanding and intent of this practice as follows:
5.4.1 No allowance or distinction is made for variables such as end-use application and duration of use. Decisions on selection of tests to be done should be made based on Practice F748.
5.4.2 This practice was originally designed for use with nonporous, solid materials. Its application for other materials, such as those that are porous, absorptive (for example, sponge-like materials that are capable of absorbing liquid), or resorptive, should be considered with caution. Consideration should be given to altering the specified material-to-liquid ratio to allow additional liquid to fully hydrate the material and additional liquid or other methods to fully submerge the test specimen. Additional procedures that fully remove the extract liquid from the test specimen, such as pressure or physically squeezing the material, should also be considered as appropriate. Although no definitions are given in this practice for the following terms, such items as extraction vehicle surface tension at the specified extraction condition and test specimen physical structure should be taken into account.
Note 1: While there are no standardized methods available at present for determining the solvent absorption capacity of an absorptive device or material, a suggested protocol is as follows: – Determine the volume of extraction vehicle that each 0.1 g or 1.0 cm2 of device/material absorbs; – then, in performing the extraction, add this additional volume to each 0.1 g or 1.0 cm2 in an extraction mixture.
5.5 Test Methods D570 and D1239 and Practices D543 may be useful in providing supplemental information.
1.1 This practice covers methods of extraction of medical plastics and may be applicable to other materials. This practice identifies a method for obtaining “extract liquid” for use in determining the biological response in preclinical testing. Further testing of the “extract liquid” is specified in other ASTM standards. The extract may undergo chemical analysis as part of the preclinical evaluation of the biological response, and the material after extraction may also be examined.
1.2 This practice may be used for, but is not limited to, the following areas: partial evaluation of raw materials, auditing materials within the manufacturing process, and testing final products. This practice may also be used as a reference method for the measurement of extractables in plastics used in medical devices. In general, it is the responsibility of the user of the standard to determine if the methods described in this standard are appropriate for the materials in their device.
1.3 This practice was initially developed for extraction of medical plastics not intended to undergo degradation or absorption during normal medical device usage. When applied to the extraction of absorbable materials, additional considerations may be necessary in the selection of extraction procedures and fluids.
1.4 For assessment of compatibility of the Single-use System material with the cell culture medium or the manufacturing processes used for cell-based therapeutics, vaccines, cell-based diagnostics, or other biopharmaceutical products, the user should refer to Guide E3231.
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.
1.6 This 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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