Moore, Hannah Elizabeth (2013) Analysis of cuticular hydrocarbons in forensically important blowflies using mass spectrometry and its application in Post Mortem Interval estimations. Doctoral thesis, Keele University.

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Abstract

Forensic entomology relies on accurate identification of forensically important blowflies to species level, preceded by ageing the Calliphorid specimens present on a cadaver to determine the post-mortem interval (PMI). The task of identifying blowflies based on morphologial criteria can be challenging due to complex keys, limited diagnostic features in the immature stages and poor preservation of entomological samples. Therefore, the
larvae will mostly be reared to adult flies to confirm identification, which is a time consuming process.

This thesis presents work examining the cuticular hydrocarbon (CHC) profiles of three forensically important blowfly species in the UK, Lucilia sericata, Calliphora vicina and Calliphora vomitoria with two main aims to this study. Firstly to establish if CHC analysis
could be used to determine whether the three species yield characteristic profiles, allowing for identification to be achieved. The second aim was to examine the hydrocarbon profiles over time to determine if chemical changes occurred at certain points in time, giving an indication of age. The CHCs were extracted from all life stages (empty egg cases, larvae, pupae, empty puparial cases and adult flies) and analysed using gas chromatography – mass spectrometry (GC-MS) and Direct-analysis-in-Real-Time MS (DART-MS).
Statistical interpretation was applied in the form of principal component analysis (PCA) and preliminary Artificial Neural Networks (ANN). Results showed species-specific characteristics within the chromatograms in all life stages, meaning distinctions can be made between the three species, even in 1st instar larvae. Significant chemical changes were observed within the hydrocarbon profiles over time, hence accurate ageing could be
established for larvae, empty puparial cases and adult flies. Early results show great potential to utilise this technique and to develop it into a highly useful identification and ageing tool.

Item Type: Thesis (Doctoral)
Additional Information: Originally available via intralibrary 2014
Subjects: Q Science > QD Chemistry > QD415 Biochemistry
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Depositing User: Lisa Bailey
Date Deposited: 08 Jun 2017 11:48
Last Modified: 08 Jun 2017 11:48
URI: http://eprints.keele.ac.uk/id/eprint/3571

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