Investigations into sampling approaches for chemical analysis of latent fingermark residue

• Published in: Forensic chemistry 2019-06, Vol.14, p.100166, Article 100166
• Main Authors: Dorakumbura, Buddhika N., Busetti, Francesco, Lewis, Simon W.
• Format: Article
• Language: English
• Subjects: Fingermark composition; GC–MS; Sampling; Squalene
• ISSN: 2468-1709; 2468-1709
• DOI: 10.1016/j.forc.2019.100166

[Display omitted] •Sampling is a key challenge in studying the chemical composition of latent fingermarks.•Four sampling protocols for the chemical analysis of latent fingermarks compared.•Squalene content of latent fingermarks on non-porous surfaces determined by GC–MS.•Sampling approach has marked effect on reproducibility of squalene content.•Controlling the deposition pressure of fingermark leads to improved reproducibility. The quantitative variation in latent fingermark deposits sampled from the same donor (intra-donor) poses considerable challenges to studies into the chemical composition of latent fingermarks. The work presented here investigates approaches to the sampling of latent fingermark residues within this context. The amount of squalene in fingermarks deposited on non-porous surfaces, determined by GC–MS, was used as an indicator of the amount of non-polar material present. It was found that the percentage difference of squalene between deposits from two hands at a given time, without controlling the deposition force, was in the range of 4–100%. This was reduced to 0–44% in alternative sampling approaches where deposition force was controlled. These results demonstrate the significant influence of sampling on subsequent chemical analysis of fingermark residues, and offer possible sampling strategies to overcome issues associated with intra-donor variation.