【国外标准】 Standard Practice for Determination of Soluble Residual Contamination by Soxhlet Extraction

5.1 It is expected that this practice will be suitable to identify and quantify contaminants found in systems, system materials, and components used in systems requiring a high level of cleanliness, such as components for oxygen service. Nonmetallic piece parts such as seals and valve seats can be tested as received. Warning—If parts being tested are to be subsequently installed in an oxygen-enriched system, residual extraction solvent remaining in the part due to inadequate drying may increase the susceptibility of the system to ignition. The extraction solvent shall be thoroughly removed from the parts prior to service.5.2 Processing materials such as gloves and wipers, or samples thereof, to be used in the cleaning operation can be evaluated prior to use to ensure that the proposed cleaning solvent does not extract contaminants that may be deposited as residues on the surface to be cleaned.NOTE 1: Test methods that do not require Soxhlet equipment, such as Test Methods E1560 and E1731, may be suitable alternatives for evaluation of processing materials. Test Method G144 with Practice G136 may be suitable for use when the material to be tested is not degraded by sonication. However, results from this test method cannot be directly compared to results from other test methods. Soxhlet extraction may be more aggressive than other extraction methods.5.3 Wipers or other cleaning supplies can be tested before and after use to determine the amount of contaminant removed from a surface. The type of contaminant removed from the surface may also be determined by qualitative analysis of the extracted NVR using analytical methods such as Fourier Transform Infrared (FTIR). This procedure can be used to obtain samples for NVR analysis using contaminated control coupons that were subjected to the cleaning process as controls to validate cleaning operations.5.4 The selection of the solvent requires some knowledge of the contaminant (see Practice G93 for recommendations). If a nonvolatile residue (NVR) analysis is to be performed on the molecular contaminant, the boiling point of the solvent shall be significantly lower than that of the contaminant. For other analytical methods, the tester must know the accuracy of the analytical methods, and the solvent shall be chosen so as not to interfere with the selected analytical method. To identify the composition of the NVR, analytical methods such as infrared spectroscopy or gas chromatography/mass spectroscopy have been used satisfactorily.1.1 This practice describes a procedure for the determination of residual contamination in materials to be used within or in contact with hardware requiring a high level of cleanliness, such as components for oxygen service, by Soxhlet extraction.1.2 This practice may be used for extracting nonvolatile and semivolatile residues from solids such as new and used gloves, new and used wipers, contaminated test specimens or control coupons, small piece parts (metallic or nonmetallic), etc. When used with proposed consumable cleaning materials (wipers, gloves, etc.), this practice may be used to determine the potential of the proposed solvent to extract contaminants (plasticizers, residual detergents, brighteners, etc.) from the cleaning material and deposit them on the surface being cleaned.1.3 This practice is not suitable for the evaluation of particulate contamination.1.4 The values stated in SI units are standard.1.5 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.1.6 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.