Fast analytical methods are highly desirable in disciplines such as forensics and proteomics. Some specific examples in forensics and other fields are the detection and verification of narcotics by enforcement agencies, monitoring the quality of foods in highly automated processing environments within the food industry, controlling airborne pathogens in medical facilities, and for environmental protection. Rapid methods free from interferences are required to screen for drugs of abuse in clandestine drug laboratories so that forensic scientists can establish a chain of evidence that link the offender to the crime scene. The implementation of fast and sensitive protocols to monitor airborne and foodborne pathogens would be beneficial as a precaution against bioterrorist releases in the atmosphere and the intentional or unintentional contamination of food with virulent microbes.
Two important techniques for rapid analysis are ion mobility spectrometry (IMS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS). IMS has been implemented for the fast screening of contraband drugs and explosives at airports, customs, borders, and crime scenes. IMS furnishes high sensitivity, low detection limits, rapid response resulting in real-time monitoring capabilities, and portability. However, IMS provides identification based on reduced mobility, which can be problematic when compounds with similar proton affinities and reduced mobilities are to be identified. MALDI TOF-MS provides the molecular weight of large organic molecules, polymers, and bio-molecules and this information is unique to each analyte.
The combination of these two techniques and their applicability on various problems of forensic and proteomic nature constitutes the basis of this dissertation. An improved detection method for the contraband methamphetamine contaminated with nicotine is proposed. In situ chemical derivatization coupled to IMS is advantageous for detecting amphetamine drugs from nicotine, which can be a pervasive contaminant. The characterization and differentiation of bacteria using chemometric modeling and in situ thermal hydrolysis methylation combined with thermal desorption IMS are discussed. A rapid and facile analytical protocol for isolating the foodborne pathogen Escherichia coli O157:H7 from aqueous media and ground beef using immunomagnetic separations is presented. The identification and confirmation of this bacterial strain by MALDI TOF-MS and database searches are also discussed.