Standard Guide for Using Micro X-Ray Fluorescence (μ-XRF) in Forensic Polymer Examinations

Importancia y uso:

4.1 µ-XRF is a nondestructive qualitative elemental analysis technique used for polymers. It involves excitation of a sample by an X-ray source resulting in the emission of characteristic X-rays detected using an energy dispersive X-ray detector. Results are displayed simultaneously as a spectrum of intensity as a function of energy for elements of atomic number 11 or greater.

4.2 µ-XRF enables the determination of the elemental composition of a specimen and can be utilized for comparisons of components of polymeric materials (for example, tape backings, tape adhesives, paint layers).

4.3 Comparisons of X-ray spectra acquired from polymer samples are conducted for source discrimination or potential association.

4.4 Quantitative processes for µ-XRF analysis are available but are not used for polymer analyses because of the lack of prepared polymer standard reference samples.

4.5 In general, information available from a heterogeneous specimen diminishes as its size is reduced or its condition degrades, which lessens its likelihood of being representative of the source material.

4.6 µ-XRF data collected from polymers is limited to specific information (for example, elements detected, relative elemental abundance); additional analytical procedures are required to further characterize and identify the chemical composition of the polymer sample.

4.7 Limitations of µ-XRF include the inability to detect some elements in trace concentrations, the inability to analyze individual particles, the potential interference related to the penetration depth of the beam relative to the sample thickness, the inability to resolve the peaks of some elements (for example, Ba Lα / Ti Kα), and the potential for discoloration of some materials due to exposure to radiation.

Subcomité:

E30.15

Referida por:

E1732-24E01

Volúmen:

14.02

Número ICS:

07.140 (Forensic science)

Palabras clave:

elemental analysis; forensic science; micro X-ray fluorescence spectrometry; paint; polymers; tape;