【国外标准】 Standard Practice for Separation of Ignitable Liquid Residues from Fire Debris Samples by Static Headspace Concentration onto an Adsorbent Tube

5.1 This practice is useful for preparing extracts from fire debris for subsequent qualitative analysis by gas chromatography-mass spectrometry, see Test Method E1618.5.2 This practice is capable of removing a portion of the headspace vapors, containing quantities smaller than 0.1 µL/L of ignitable liquid residues, from a sample container and concentrating the ignitable liquid residues onto an adsorbent medium (1).5.2.1 Recovery from fire debris samples will vary, depending on factors including debris temperature, adsorbent temperature, container size, adsorptive material, headspace volume, sampling volume or sampling time and flow rate, and adsorptive competition from the sample matrix (2).5.3 The principal concepts of static headspace concentration are similar to those of static headspace (Practice E1388) and dynamic headspace concentration (Practice E1413). The static headspace concentration technique can be more sensitive than the static headspace technique and less sensitive than the dynamic. The static techniques do however leave the sample in a condition suitable for resampling, as only a portion, typically less than 10 %, of the headspace is withdrawn from a sample container (3).5.3.1 Re-sampling and analysis is possible with static headspace concentration onto an adsorbent tube, because only a portion of the headspace from the container is removed (3). Taking multiple headspace samples will continuously reduce the concentration of ignitable liquid vapors present, which can result in a change in relative composition of components and eventually non-recovery when the questioned headspace originally contained very low quantities of ignitable liquid residues (less than 0.1 µL/L).5.4 Common solid adsorbent/desorption procedure combinations in use are activated carbon/solvent elution and Tenax4 TA/thermal desorption.5.5 Solid adsorbent/desorption procedures not specifically described in this standard can be used as long as the practice has been validated as outlined in Section 11.1.1 This practice describes the procedure for separation of ignitable liquid residues from fire debris samples using static headspace concentration onto an adsorbent tube, for subsequent solvent elution or thermal desorption.1.2 Static headspace concentration onto an adsorbent tube involves removal of a headspace extract from a sample container (typically a jar, can, or bag), through a small hole punctured in the container, using a syringe or pump.1.3 Static headspace concentration systems for adsorption onto an adsorbent tube are illustrated and described.1.4 This practice is suitable for preparing extracts from fire debris samples containing a range of volumes (µL to mL) of ignitable liquid residues, with sufficient recovery for subsequent qualitative analysis (1).21.5 Alternative headspace concentration methods are listed in Section 2 (see Practices E1388, E1412, E1413, and E2154).1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.7 This standard cannot replace knowledge, skills, or abilities acquired through education, training, and experience (Practice E2917) and is to be used in conjunction with professional judgment by individuals with such discipline-specific knowledge, skills, and abilities.1.8 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.1.9 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.