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Title: Medicines authentication using nuclear quadrupole resonance
Author: Kyriakidou, Georgia
ISNI:       0000 0004 5991 1300
Awarding Body: King's College London
Current Institution: King's College London (University of London)
Date of Award: 2016
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Nuclear Quadrupole Resonance (NQR) is a radio-frequency (RF) spectroscopic technique, that allows the detection of solid-state compounds containing quadrupolar nuclei; a property of the majority of pharmaceutical products. This thesis investigates the application of NQR in medicines authentication, where accurate \ fingerprints" of the examined materials must be obtained, in response to the global threat of low quality and counterfeit medicines. In practice, a complete NQR system contains a database with profiles of commercial medicines, built using characteristic features of the NQR signals. However, several issues including the weak NQR signals, prolonged measurement times and the evident variability among medicines can influence the accuracy of the profiles and limit the current use of NQR in the field. The expected signal amplitude is often affected by the uncertainty regarding the compound's temperature, which may cause the signalto- noise ratio (SNR) to be substantially reduced; this phenomenon is commonly known as o -resonance effects. An extended echo-train signal data model is introduced, which exploits the dependence of the signal amplitude on the o -resonance excitation frequency and temperature. Herein, the Cramer-Rao lower bound, able to efficiently determine conditions for optimised detection, is derived. The stability and degradation of medicines is influenced by several factors. Being able to determine the variability between medicines produced by the same manufacturer is crucial in medicines authentication. Herein, the investigation of batch-to-batch variability of analgesic paracetamol of the same producer is presented, with the findings pointing out the need for long term monitoring of a product's \ fingerprint". Last, a study is presented that focuses on versatile methodologies which can reduce the measurement times by identifying limits in the accuracy of the estimation parameters. The results indicate that these proposed solutions can help optimising the utility of the applied signal processing method.
Supervisor: Althoefer, Kaspar Alexander ; Seneviratne, Lakmal Dasarath Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available