Applications of chromatography, spectroscopy, and capillary electrophoresis to the analysis of forensic samples

Gas chromatography/mass spectrometry (GC/MS), capillary electrophoresis (CE), Fourier transform infrared (FT-IR), and ultraviolet-visible (UV-visible) and fluorescence spectroscopy are frequently used for forensic analyses.; GC/MS is used to confirm the presence of drugs in biological samples. In these common analyses, sensitivity and high throughput are very important. Designed experiments were used to optimize sensitivity, separation quality and analysis time for analysis of benzodiazepines and benzodiazepine metabolites from blood and urine samples using fast GC/MS. The effects of temperature program and carrier gas flow on analysis time, sensitivity, and separation quality were characterized. Using fast temperature programming and selected ion monitoring, mixtures of up to 12 benzodiazepines were analyzed with 5 min run times. The sensitivity of gas chromatographic analyses can be improved by using of large volume injection (LVI) methods. A method to facilitate limited LVI for GC without special equipment was developed. Injection of up to 10 muL ethyl acetate sample solution was possible on a standard split/splitless injector. The method produced linear calibration curves and the improvement in sensitivity was proportional to the additional analyte injected. The method was applied to common toxicological analytes.; FT-IR is commonly used for identification of polymer subclasses of forensic fiber evidence. The usefulness of peak ratio analysis and multivariate statistics for the identification of nylon subclasses using attenuated total reflectance FT-IR spectroscopy was investigated. Principal component analysis followed by linear discriminant analysis, was able to correctly classify a set of 270 spectra from eight different subclasses with 98.5% cross-validation accuracy.; UV-visible and fluorescence microspectrophotometry are commonly used to analyze dyed fibers. The ability of these techniques to discriminate between fibers dyed with different fluorescent brighteners applied by the textile manufacturer was investigated. Absorbance and fluorescence caused by fluorescent brighteners on mounted fibers be detected without significant interference from the mounting material. Comparison of fluorescence spectra by visual analysis and multivariate data analysis showed that fluorescence microspectroscopy could differentiate between all nine different fluorescent brighteners used in this study.; CE has many applications in forensics. A practical capillary electrophoresis-diode array detector-mass spectrometry (CE-DAD-MS) interface for the analysis of dyes was designed and implemented.