Evaluation of plasma cleaning as an approach for the preparation of soil minerals for forensic comparison by photon and electron microscopy

This study exposed grains of known mineral types to 20 min of a low-pressure O2 plasma generated by a 10 MHz frequency generator. Powder x-ray diffraction was chosen as an independent method to evaluate the minerals for chemical or structural changes caused by this ashing process. Side-by-side comparison of before and after diffractograms revealed minimal, if any, variation in the detected 2θ and subsequently calculated d-spacing: differences in d values were found to generally be less than 1%, and most were within Hanawalt Search Index uncertainties by no less than a full order of magnitude. Peak intensity changes were similarly minimal. This study strongly suggests that low-temperature plasma ashing can be used for the isolation of inorganic soil material fraction for forensic soil analysis with little or no concern for potential alteration of the mineral grains.PMID:33645630 | DOI:10.1111/1556-4029.14693
Source: Journal of Forensic Sciences - Category: Forensic Medicine Authors: Source Type: research