Method optimization of fingermark residue using comprehensive two- dimensional gas chromatography

Význam tématu

Optimizing the analysis of fingermark residue by comprehensive two-dimensional gas chromatography (GC×GC) advances forensic science by enabling detailed chemical profiling of latent prints. Such non-targeted methods reveal endogenous and exogenous compounds that support donor characterization beyond ridge pattern matching.

Cíle a přehled studie

The study had two primary objectives:

1. Develop and optimize a GC×GC method using helium as a carrier gas for non-targeted identification of fingermark residue compounds.
2. Translate the optimized helium method into an efficient hydrogen-based GC×GC approach that maintains chromatographic resolution while reducing analysis time and cost.

Použitá metodika

Sample collection employed cotton swab extraction followed by centrifugation in spin baskets, solvent blow-down, and reconstitution. Method optimization evaluated parameters such as modulation periods (3–5 s), hot pulse durations (1–1.5 s), oven hold times at start (1–5 min) and end (8–12 min), temperature ramps (5–15 °C/min), and secondary oven offsets (5–10 °C). Chromatograms acquired before and after optimization demonstrated improved peak capacity and resolution.

Použitá instrumentace

Analysis was performed on a comprehensive two-dimensional gas chromatograph equipped with a thermal modulator and dual ovens. Helium and hydrogen carrier gases were modeled using proprietary software to predict retention and resolution. The optimized helium method was translated to hydrogen using a Restek GC×GC method translator.

Hlavní výsledky a diskuse

Optimization yielded enhanced separation of sterols, fatty acid methyl esters, fatty alcohols and steroids. Unexpected anthropogenic constituents such as sunscreen agents (octocrylene, octisalate, avobenzone), plasticizers (diisopropyl adipate, phthalates) and vitamin E acetate were resolved. Hydrogen-based methods (“translate” and “speed” profiles) provided comparable resolution in congested regions. The “H2 Translate” protocol was selected for its higher number of identifiable peaks and favorable squalene and cholesterol peak shapes.

Přínosy a praktické využití metody

Enhanced non-targeted profiling improves donor characteristic assignment (e.g., sex, age group) and strengthens evidentiary value where fingerprint patterns are smudged. The hydrogen-based method reduces runtime and helium dependency, lowering operational costs while preserving forensic utility.

Budoucí trendy a možnosti využití

• Integration of high-resolution mass spectrometry for compound confirmation and expanded biomarker discovery.
• Miniaturized or portable GC×GC systems for field deployment at crime scenes.
• Machine learning algorithms applied to complex chromatographic data for automated donor profiling.
• Development of standardized libraries for forensic fingermark compounds.

Závěr

The optimized GC×GC helium method and its translation to a hydrogen-based protocol demonstrate robust, high-capacity separation of fingermark residue components. This workflow enhances forensic chemical profiling and offers a cost-effective alternative through hydrogen carrier gas without sacrificing resolution.

Reference

• Primeau D. et al. Journal of Forensic Sciences. 68 (2023).
• Archer N.E. et al. Forensic Science International. 154 (2005) 224–239.
• Kindell J., Bridge D. Forensic Chemistry. 32 (2023).