The Utilization of Chiral Ion Mobility Spectrometry for the Detection of Enantiomeric Mixtures and Thermally Labile Compounds

• Main Author: Holness, Howard K.
• Format: Others
• Published: FIU Digital Commons 2013
• Subjects: electrospray; ion mobility; mass spectrometry; chiral; explosives; Analytical Chemistry; Evidence; Laboratory and Basic Science Research; Science and Technology Law
• Online Access: http://digitalcommons.fiu.edu/etd/988; http://digitalcommons.fiu.edu/cgi/viewcontent.cgi?article=2102&context=etd

This dissertation utilized electrospray ion mobility mass spectrometry (ESI-IMS-MS) to develop methods necessary for the separation of chiral compounds of forensic interest. The compounds separated included ephedrines and pseudoephedrines, that occur as impurities in confiscated amphetamine type substances (ATS) in an effort to determine the origin of these substances. The ESI-IMS-MS technique proved to be faster and more cost effective than traditional chromatographic methods currently used to conduct chiral separations such as gas and liquid chromatography. Both mass spectrometric and computational analysis revealed the separation mechanism of these chiral interactions allowing for further development to separate other chiral compounds by IMS. Successful separation of chiral compounds was achieved utilizing a variety of modifiers injected into the IMS drift tube. It was found that the modifiers themselves did not need to be chiral in nature and that achiral modifiers were sufficient in performing the required separations. The ESI-IMS-MS technique was also used to detect thermally labile compounds which are commonly found in explosive substances. The methods developed provided mass spectrometric identification of the type of ionic species being detected from explosive analytes as well as the appropriate solvent that enhances detection of these analytes in either the negative or positive ion mode. An application of the developed technique was applied to the analysis of a variety of low explosive smokeless powder samples. It was found that the developed ESI-IMS-MS technique not only detected the components of the smokeless powders, but also provided data that allowed the classification of the analyzed smokeless powders by manufacturer or make.