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There are numerous problems associated with the analysis of samples from mass produced goods if the resulting data are intended for use in court. Currently, many methods do not provide a definitive answer to the question if two chemically identical samples share the same provenance, so new techniques are being tested to overcome this problem. Isotope Ratio Mass Spectrometry (IRMS) measures stable isotope abundance, a compound characteristic that can provide information as to the provenance of natural and synthetic substances. The potential use of IRMS to determine both source and origin of natural substances has been tested with some success identifying for example geographical origin of drugs such as heroin and cocaine (Ehleringer et al. 1999). The aim of this thesis was to study the application of stable isotope analytical techniques to two representatives of mass produced goods, namely architectural white paint and wooden safety matches. Existing analytical techniques are not sufficient for the forensic examination of architectural paint. The proposed solution was stable isotope profiling using IRMS. Background studies were carried out to determine potential intra and inter-batch variability of paint samples. This was followed by studies of 51 architectural white paints, which showed the considerable potential of stable isotope profiling when combined with likelihood ratios as a forensic statistical tool. The results from IRMS were compared to other analytical methods. Wooden matches are items commonly encountered at a variety of crime scenes. However prior to this thesis, no established comparative method of forensic analysis existed for this. type of sample. Wooden matches were analysed by IRMS and the results compared to microscopy and X-ray diffraction. Each of the techniques produced complimentary data and allowed the differentiation of two sets of matches seized in an actual criminal investigation. The analysis of burnt wooden matches by IRMS showed considerable potential for even when samoles were burnt. Supplied by The British Library - 'The world's knowledge'

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This thesis begins with an introduction into some of the mechanisms utilised in fluorescent sensing, in particular photoinduced electron transfer and internal charge transfer which \t'\I13re central to the operation of the probes selected for this ,--, l' study. The simplicity and diversity of such sensors is also outlined with examples from the literature showing various compounds designed with specific targets in mind and an indication of future sensors. Chapter two focuses on developing a chemo-sensor to monitor the level of polyhexamethylene biguanide (PHMB), an antimicrobial agent used as an alternative to chlorine in the treatment of swimming pools. Pyrazoline based fluorescent sensors were investigated in order to decrease the magnitude of detection, when compared to the conventional fluorescein derived colorimetric method. Chapter three attempts to add another dimension to the information retrieved from a molecular probe. Sensors were developed to monitor the proton concentration at the boundary of cells. Micelles (CTAC, SLS and Triton-X100) were used as membrane mimics. The sensors were composed of a lipophilic head group connected via a tertiary amine (proton receptor) to the fluorophore (naphthalimide). By varying the lipophilic nature of the head group in a series of compounds, the location of the receptor can be tuned, resulting in a mapping of the local proton density relative to one another. The thesis is concluded with chapters four and five containing the . experimental procedures and references respectively.

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