Laser Desorption/Ionization Time‐of‐Flight Mass Spectrometry of Triacylglycerols and Other Components in Fingermark Samples*

Abstract

The chemical composition of fingermarks could potentially be important for determining investigative leads, placing individuals at the time of a crime, and has applications as biomarkers of disease. Fingermark samples containing triacylglycerols (TAGs) and other components were analyzed using laser desorption/ionization (LDI) time-of-flight mass spectrometry (TOF MS). Only LDI appeared to be useful for this application while conventional matrix-assisted LDI-TOF MS was not. Tandem MS was used to identify/confirm selected TAGs. A limited gender comparison, based on a simple t-distribution and peaks intensities, indicated that two TAGs showed gender specificity at the 95% confidence level and two others at 97.5% confidence. Because gender-related TAGs differences were most often close to the standard deviation of the measurements, the majority of the TAGs showed no gender specificity. Thus, LDI-TOF MS is not a reliable indicator of gender based on fingermark analysis. Cosmetic ingredients present in some samples were identified.

Fingerprint composition and aging: A literature review

“…The development of enhancement techniques [7,31,33,[36][37][38][39]47,48,132,140] 2. The development of fingerprint age determination methods [7,36,39,51,67,79] Increased knowledge of fingerprint composition allows for increased comprehension of the chemical mechanisms that occur between enhancement reagents and their target compounds, as well as how they interact within the 3D matrix. This allows for improvements to both existing reagents and novel developments with a high level of effectiveness for both fresh and old fingerprints [3].…”

“…Readers are directed elsewhere for further information regarding contaminants. Thirdly research has explored the potential for fingerprint age determination through changes to composition over time [20,[33][34][35][36][37][38][39][40][41]. There are currently no accepted analytical methods for reliably determining fingerprint age.…”

Fingermark initial composition and aging using Fourier transform infrared microscopy (μ-FTIR)

“…Numerous analytical techniques have been used in order to gain more fundamental knowledge about initial fingermark composition. Gas chromatography mass spectrometry (GC/MS) [1][2][3][4][5][6][7][8][9][10][11], advanced mass spectrometry techniques (e.g., laser desorption, electrospray or atmospheric pressure chemical ionisation) [12][13][14][15][16][17][18][19], Raman spectroscopy [20][21][22][23][24][25] and Fourier transform infrared spectroscopy combined with a microscope (m-FTIR) have been applied in this context. Other studies have also been carried out in order to study the changes occurring in fingermark composition over time.…”

An update on MALDI mass spectrometry based technology for the analysis of fingermarks – stepping into operational deployment

“…attempted to obtain such intelligence exploiting the lipidic content of the marks but the reports concluded that the methods were either not conducive to the desired information or the data were not statistically significant 49,50 .…”

“…Laser Desorption Ionisation (LDI) 8 , Soft-Landing Ion Mobility of Silver Clusters -LDI, and gold nanoparticles enhanced target (AuNPET) -LDI 9 , MeV-SIMS 10 , Xray photoelectron spectroscopy (XPS) 10 , Liquid Extraction Surface Analysis (LESA) 11 , Laser Activated Electron Tunnelling (LAET) 12 and Easy Ambient Sonic-Spray Ionization Mass Spectrometry (EASI MS) 13 . This latter (ii) category of techniques, despite some limitations, could overcome some difficulties presented by some of the technologies outside the "other techniques" group; for example, AuNPET -LDI 9 enables fingermark visualisation on surfaces treatable via gold sputtering, yielding the biometric information, whilst allowing mass spectrometric imaging analysis to be performed avoiding the use of an organic matrix (used in MALDI).…”