Analysis of Fatty Acid Components in Fingerprint Residues by Gas Chromatography-Mass Spectrometry

As an important trace evidence,fingerprints are widely used in personal identification and disclosure of criminal acts at the crime scene. Traditional fingerprint studies mainly focus on morphological analysis,while the in-depth exploration of its chemical constituents has always been neglected. In comparison, the chemical analysis of fingerprint substances can better improve the sensitivity and scientificity of fingerprint inspection technique. In this work,by taking the fatty acid in the fingerprint substance as the target,a new method was explored to measure the fatty acid by gas chromatography-mass spectrometry and applied to the analysis of real fingerprint samples. Experiment results showed that when the concentration of hydrochloric acid/methanol solution was 5% (V/ V),the derivative temperature was 50 degrees C,the derivative time was 20 min,and the derivative reagent amount was 400 mu L,the fatty acid components in fingerprint residues could be detected more accurately. On this basis,the method was applied to the detection of lipid composition in real fingerprint samples,which identified the standard detection process for fingerprint samples and proved a quite obvious individual difference in lipid composition in fingerprint residues. The lipid composition of four fingerprints left by 2 volunteers on the same day was analyzed and the main components with 99? 7% of the cumulative variance contribution rate by employing the principal component analysis method was retained, which demonstrated a strong correlation between the lipid composition of these fingerprints,further proving the stability and reproducibility of the fingerprint lipid composition detection method. This work might lay a research foundation for further exploration of employing fingerprint substances to identify individuals.

Automated summary

This study explored a new method to measure the fatty acid components in fingerprint substances, improving the sensitivity and scientificity of fingerprint inspection technique. The experiment results showed that the method accurately detected the fatty acid components in fingerprint residues and revealed significant individual differences in fingerprint lipid composition.