Forensic Value of Triacylglycerols in Mass Spectrometry Imaging of Latent Fingerprints

Thursday, March 11, 2021: 2:30 PM - 2:50 PM

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Description

Mass spectrometry imaging (MSI) is a promising analytical technique to obtain chemical information of fingerprints thanks to its high sensitivity, label-free detection, and unbiased molecular characterization. Triacylglycerol (TG) is a major class of endogenous compounds in fingerprints and is readily detected in matrix-assisted laser desorption ionization (MALDI)-MSI analysis. The analysis of a fingerprint results in a complex but characteristic TG spectral pattern with a 14 Da and 2 Da series, which is originated from various chain length and double bonds of the three fatty acyl chains on the glycerol backbone. Despite readily detectable TG signals, the forensic value of this class of endogenous compounds has been largely unexplored. Presented in this talk are two potential uses of TG profiles as forensic evidence. First, we found each individual has a somewhat unique pattern of TG profiles. In a small group study, we demonstrated the fatty acyl distribution is affected by an individual’s health status, particularly exercise, diet and possibly metabolic disease. Second, as a fingerprint ages, unsaturated TGs were found to degrade over time producing O7 and O8 molecular species in MALDI-MS. It was attributed to ambient ozonolysis of double bonds resulting in an ozonide which is subject to in-source fragmentation during MALDI-MS. The degradation pattern is reproducible for each individual suggesting it can be used to determine the age of fingerprints. Also demonstrated will be some early work on the effect of temperature, light, humidity, and ozone concentration in fingerprint aging using an environmental chamber, as well as TG profiles of fingerprints from diabetes patients in a large-scale study.

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Additional Info

Keywords: Please select up to 4 keywords ONLY:
Laser Desorption (MALDI),Trace Analysis