In the area of forensic chemistry, improved or new analysis methods are continually being investigated. One common and powerful technique used in forensic chemistry is wall-coated open-tubular column (WCOT) gas chromatography with electron ionization single quadrupole mass spectrometry (GC-MS). Improvements to and effectiveness of alternatives to this instrumental platform were explored in an array of parallel inquiries. The areas studied included the column for the chromatographic separation, the universal detection method employed, and the fragmentation method used to enhance molecular identification. <br><br>Superfine-micropacked capillary (SFµPC) columns may provide an alternative to commercial packed GC columns and WCOT GC columns that combines the benefits of the larger sample capacity of packed columns and the benefits of the excellent separation capabilities and mass spectrometry (MS) flow rate compatibility of WCOT columns. SFµPC columns suffer from high inlet pressure requirements and prior reported work has required specialized instrumentation for their use. Fabrication of and chromatography with SFµPC GC columns was successfully achieved with typical GC-MS instrumentation and within the flow rate limit of a MS. Additionally, the use of higher viscosity carrier gasses was demonstrated to reduce the required inlet pressure for SFµPC GC columns.<br><br>Recently, a new vacuum ultraviolet spectrometer (VUV) universal detector has been commercialized for GC. The ability of VUV detectors to acquire absorbance spectra from 125 nm to 430 nm poses a potential alternative to MS. As such, GC-VUV provides an exciting potential alternative approach to achieving excellent quantitative and qualitative analysis across a wide range of analytes. The performance of VUV and MS detectors for forensic analysis in terms of quantitative and qualitative analysis was compared. Analysis of alkylbenzenes in ignitable liquids was explored, which can be important evidence from suspected arson fires and are difficult to differentiate with MS. The VUV detector was found to have superior specificity and comparable sensitivity to the MS detector in scan mode.<br><br>Addition of thermolysis (Th) as an orthogonal fragmentation pathway provides the opportunity to increase the differences between MS fragmentation patterns. Fragmentation has been widely established to aid in identification of molecules with MS by providing characteristic fragments at characteristic relative abundances. However, molecules with very similar structures do not result in sizable spectral differences in all cases with typical MS fragmentation techniques. A series of Th units were fabricated and integrated into GC-Th-MS instruments. Th-MS was conducted with the thermally labile nitrate esters across a range of instrumentation and thermal conditions.<br>

<p>The rapid analysis of complex samples using mass spectrometry (MS) provides valuable information in both point-of-care (e.g. drug testing) and laboratory-based applications, including the generation of spectral libraries for classification of biosamples, the identification of biomarkers through large-scale studies, as well as the synthesis and bioactivity assessments of large compound sets necessary for drug discovery. In all these cases, the inherent speed of MS is attractive, but rarely fully utilized due to the widespread use of sample purification techniques prior to analysis. Ambient ionization methodologies can help circumvent this drawback by facilitating high-throughput qualitative and quantitative analysis directly from the complex samples without any need for work-up. For instance, the use of swabs or paper substrates allows for rapid identification, quantification, and confirmation, of drugs of abuse from biofluids or surfaces of forensic interest in a matter of minutes, as described in the first two chapters of this dissertation. Faster analysis can be achieved using an automated desorption electrospray ionization (DESI) platform which allows for the rapid and direct screening of complex-sample microarrays with throughputs better than 1 sample per second, giving access to rich spectral information from tens of thousands of samples per day. The development of the bioanalytical capabilities of this platform, particularly within the context of drug discovery (e.g. bioactivity assays, biosample analysis), is described across most other chapters of this dissertation. The use of DESI, a contactless ambient ionization method developed in our laboratory and whose 20 years of history are overviewed in the introduction of this document, provides an additional advantage as the secondary microdroplets generated through the DESI process act as reaction vessels that can accelerate organic reactions by up to six orders of magnitude, facilitating on-the-fly synthesis of new compounds from arrays of starting materials. Unique implications of this microdroplet chemistry in the prebiotic synthesis of peptides and spontaneous redox chemistry at air-solution interfaces, together with its practical applications to the synthesis of new drug molecules, are also overviewed. The success obtained with the first automated DESI-MS system, developed within the DARPA Make It program, led to increased interest in a new-generation platform which was designed over the past year, as overviewed in the last section of this dissertation, and which is currently being installed for validation prior to the transfer of the technology to NCATS, where we anticipate it will make a significant impact through the consolidation and acceleration of the early drug discovery workflow.</p>

In forensic chemistry, a quicker and more accurate analysis of a sample is always being pursued. Speedy analyses allow the analyst to provide quick turn-around times and potentially decrease back-logs that are known to be a problem in the field. Accurate analyses are paramount with the futures and lives of the accused potentially on the line. One of the most common methods of analysis in forensic chemistry laboratories is gas chromatography, chosen for the relative speed and efficiency afforded by this method. Two major routes were attempted to further improve on gas chromatography applications in forensic chemistry.<br> The first route was to decrease separation times for analysis of ignitable liquid residues by using micro-bore wall coated open-tubular columns. Micro-bore columns are much shorter and have higher separation efficiencies than the standard columns used in forensic chemistry, allowing for faster analysis times while maintaining the expected peak separation. Typical separation times for fire debris samples are between thirty minutes and one hour, the micro-bore columns were able to achieve equivalent performance in three minutes. The reduction in analysis time was demonstrated by analysis of ignitable liquid residues from simulated fire debris exemplars.<br> The second route looked at a relatively new detector for gas chromatography known as a vacuum ultraviolet (VUV) spectrophotometer. The VUV detector uses traditional UV and far-ultraviolet light to probe the pi and sigma bonds of the gas phase analytes as well as Rydberg traditions to produce spectra that are nearly unique to a compound. Thus far, the only spectra that were not discernable were from enantiomers, otherwise even diastereomers have been differentiated. The specificity attained with the VUV detector has achieved differentiation of compounds that mass spectrometry, the most common detection method for chromatography in forensic chemistry labs, has difficulty distinguishing. This specificity has been demonstrated herein by analyzing various classes of drugs of abuse and applicability to “real world” samples has been demonstrated by analysis of de-identified seized samples.<br>