Synthesis, characterisation and application of novel quinones for the detection of latent fingermarks

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Identification of an individual through fingermarks is one of the oldest types of evidence in forensic science. A number of techniques are available for the detection of latent fingermarks on porous surfaces; for example 1,2‐indanedione zinc (IND‐Zn), 1,8‐diazafluoren‐9‐one (DFO), and ninhydrin. While these techniques produce excellent results, each has their drawbacks. For example, ninhydrin requires secondary post-treatment and cooling with liquid nitrogen to produce fluorescent fingermarks. DFO developed fingermarks are difficult to detect on coloured or highly patterned surfaces. IND‐Zn produces a highly fluorescent fingermark, however, under white light little contrast exists between the fingermark and the substrate. Therefore, there is need for research into the development of new fingermark reagents. Quinones have been used for the development of amino acids in chromatography and biochemistry. Recent research into the use of 2‐hydroxy‐1,4‐naphthoquinone (lawsone) has shown promising results for the development of latent fingermarks on porous surfaces. One of the aims of this thesis was to determine the reaction products between lawsone and three amino acids. These products were elucidated using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and quadrupole time‐of‐flight liquid chromatography‐mass spectrometry (LC‐QTOF‐MS). The proposed product is hypothesised to be similar between benzoquinones, naphthoquinones and anthraquinones as they differ only by π conjugation. Another aim of this thesis was to synthesise a variety of quinones with differences in conjugation and substitution in order to compare and determine differences in quantum yield and whether these effects would influence their ability to develop latent fingermarks on porous surfaces. A number of quinones were successfully synthesised and characterised using FTIR and NMR spectroscopy and LC‐MS. In this preliminary study, the synthesised quinones and lawsone were then evaluated as potential reagents for the development of latent fingermarks on porous surfaces. The development conditions, reagent concentration, solvent system, pH, and metal salts enhancements of each quinone were optimised using amino acids and fingermarks on different porous surfaces. All the quinones that were tested in this thesis did not produce coloured fingermarks and only developed faintly coloured amino acid test strips. Slight improvements in luminescence were observed when comparing the results of the amino acids and fingermarks developed by naphthoquinones and anthraquinones. This is this is likely due to steric hindrance preventing anthraquinones from forming the desired products. Comparisons were also made between the fingermarks developed by the synthesised compounds and IND‐Zn, with IND‐Zn developed fingermarks being far superior in luminescence.
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