Development of Atmospheric Pressure Plasma Based Desorption-Ionisation Sources for Mass Spectrometry

• Main Author: Fletcher, Carl
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2018
• Subjects: Electrical engineering
• ISBN: 9798684611032

Ambient ionisation mass spectrometry is a rapidly increasing field, largely dominated by ambient ionisation sources that are dependent upon plasma formation. This thesis discusses attempts to create a plasma based ionisation source used at atmospheric pressure to be integrated with mass spectrometry for small molecule analysis such as drugs and explosives detection. The important features of the plasma ionisation source were to provide a rapid analysis technique which required little or no sample preparation, minimal consumables and a large sampling surface area.The plasma sources developed in this study were used to treat various surface types replicating banknotes for drugs on money analysis, ensuring that plasma treatment was not detrimental to their integrity. Furthermore, the plasma sources were all coupled with various mass spectrometers for sample analysis and were successfully able to detect various drugs and explosives in both positive and negative ion modes at low nanogram to picogram detection limits. The evidence that these plasma sources are capable of ionising in both positive- and negative-ion modes suggests the possibility of other applications within small molecule analysis.Most importantly, these plasma sources are able to detect drugs and explosives with very minimal sample preparation even from UK polymer banknotes without destroying them. This technique reduces consumable costs; whilst affording great sensitivity, speed, high-throughput, selectivity and specificity. As these plasma sources have been coupled with various mass spectrometers, it is possible that they will be readily coupled with other detectors such as ion mobility spectrometry.