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Title: Developing a methodology to enhance the chemical analysis of latent fingerprints using MALDI-MS
Authors: Koh, Xing Zhe
Keywords: DRNTU::Engineering::Materials
Issue Date: 2019
Abstract: The use of fingerprint patterns to solve crime was already started in the 19 centuries. Today, technological advancements have allowed the use of chemical components in the fingerprints to solve crime other than using fingerprint patterns. Matrix assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-ToF-MS) and surface assisted laser desorption ionisation time-of-flight mass spectrometry (SALDI-ToF-MS) are able to analyse the chemical residues in fingerprints to obtain critical information of the individual. In crime scenes, investigators have to use lifting tapes to lift off latent fingerprints and send them to laboratory for chemical analysis. Before the sample is sent for analysis, the lifting tape needs to be flipped over to expose the fingerprint residues. As such, there is no matrix on top of the residues. After analysis is done, the intensity of specific analytes is so low that it is not detectable. In this study, investigation is carried out to determine which treatment (combination of matrix type and method of applying matrix) can achieve the highest intensity values of the chemical components in the lifted fingerprints. 2 types of matrices were applied on lifted fingerprints and various methods of applying these matrices were being used. It was concluded that the treatment of dusting hydrophilic APTES-CB nanoparticles on lifted fingerprints was the best treatment to increase the intensity of specific analytes present in the fingerprints. The coefficient of variation (CV) of this treatment was being studied and it showed good repeatability. Latent fingerprints were being lifted off twice to investigate the difference in intensity between 1st lift off and 2nd lift off. It was observed that there was a difficulty in determining which lift off had the high intensity due to inconclusive results. However, 2nd lift off of dusted lifted fingerprint when compared to the 2nd lift off of control showed conclusive results. It was observed that the dusted lifted print had a higher intensity than control. As such, applying matrix on lifted fingerprint improved intensity. Latent fingerprints were also being lifted off multiple times to investigate the trend of intensity of dusted lifted fingerprint. Results showed that it was unable to determine the trend. It was then inferred that was a level of difficulty in controlling the amount of fingerprint residues being lifted off which can be due to the quality of tape. However, it was proven that applying matrix on lifted fingerprints was able to increase intensity when the final lift off of dusted lifted print was compared to the control. In conclusion, from the experiments, it was proven that applying matrix on lifted fingerprints increased the intensity of the analytes in fingerprints. To further improve the intensity, other matrices can be looked up to study their performance. Advanced equipment can also be utilised to further aid in the methods of applying these matrices.
Rights: Nanyang Technological University
Fulltext Permission: restricted
Fulltext Availability: With Fulltext
Appears in Collections:MSE Student Reports (FYP/IA/PA/PI)

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