ASTM E3294-22

5.1?The overarching goals of the forensic analysis of geological materials include (5.2?Within the analytical scheme of geological materials, XRD analysis is used to: identify the crystalline components within a sample; identify the crystalline components separated from a mixture, typically clay-sized material (see 8.8), or a selected particle class for which additional analysis is needed (see 8.11); or compare two or more samples based on the identified crystalline phases or diffraction patterns (see 11.5).

5.3?This guide is intended to be used with other methods of analysis (for example, polarized light microscopy, scanning electron microscopy, palynology) within a more comprehensive analytical scheme for the forensic analysis or comparison of geological materials.

1.1?This guide covers techniques and procedures for the use of powder X-ray diffraction (XRD) in the forensic analysis of geological materials (to include soils, rocks, sediments, and materials derived from them such as concrete), to enable non-consumptive identification of solid crystalline materials present as single components or multi-component mixtures.

1.2?This guide makes recommendations for the preparation of geological materials for powder XRD analysis with adaptations for samples of limited quantity, instrumental configuration to generate high-quality XRD data, identification of crystalline materials by comparison to published diffraction data, and forensic comparison of XRD patterns from two or more samples of geological materials to support criminal investigations.

1.3?UnitsThe values stated in SI units are to be regarded as standard. Other units are avoided, in general, but there is a long-standing tradition of expressing X-ray wavelengths and lattice spacing in units of ?ngstr?ms (?). One ?ngstr?m = 10¹⁰ meter (m) = 0.1 nanometer (nm).

1.4?This standard is intended for use by competent forensic science practitioners with the requisite formal education, discipline-specific training (see Practice E2917), and demonstrated proficiency to perform forensic casework.

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.