Exploring expanded wavelength regions with solid state focal plane detectors

This dissertation research has focused on the design of two spectroscopic instruments that operate outside of the UV/visible region for the analysis of volatile organic hydrocarbons and hard-to-separate hydrocarbon mixtures. The first design was solid state near infrared spectrometer. The fast acquisition rate of the NIR spectrometer allowed the monitoring of the bromination of 1-hexene. The concentrations of 1-hexene and 1,2-dibromohexane were determined for the reaction using classical least squares. The root mean squared errors of prediction for 1-hexene and 1,2-dibromohexane concentrations were 0.01 and 0.003 M, respectively. This research project also focused on the investigation of the effects of instrumental parameters on partial least squares models by comparing the results obtained from four different spectrometers. The results indicate that instrumental parameters, such as resolution and wavelength coverage, have a larger effect on experimental results than the analysis method (NIR or Raman). The second instrument design investigated here was a vacuum ultraviolet ICP-AES which monitored the 130 to 200 nm wavelength range. Fifteen nonmetals were used to determine the quantitative characteristics of the design. All elements demonstrated detection limits in the ppb range. The most sensitive emission line in this work was the aluminum 167.079 nm line which had a detection limit of 200 ppt. A VUV atomic emission line database was developed to provide an analytical reference for future investigations. The database included the emission lines from 76 elements over the 130 to 195 nm wavelength region. Over 2200 lines were observed and reported. Over 1000 of the lines were previously unreported in the two major existing references for the VUV. This work is the first VUV reference to provide truly comparable intensities for a large number of elements. A GC-VUV-ICP-AES was developed to investigate the potential of VUV-ICP atomic emission spectroscopy to provide both quantitative and qualitative information for mixtures. Chlorine and carbon chromatograms were obtained simultaneously for volatile organic hydrocarbon (VOC) mixtures. The work showed that GC-VUV-ICP-AES has the potential of generating empirical formulas for compounds by simultaneously quantitating each element in the compound and determining their ratios

Comparison of spectroscopically measured tissue alcohol concentration to blood and breath alcohol measurements

Alcohol testing is an expanding area of interest due to the impacts of alcohol abuse that extend well beyond drunk driving. However, existing approaches such as blood and urine assays are hampered in some testing environments by biohazard risks. A noninvasive, in vivo spectroscopic technique offers a promising alternative, as no body fluids are required. The purpose of this work is to report the results of a 36-subject clinical study designed to characterize tissue alcohol measured using near-infrared spectroscopy relative to venous blood, capillary blood, and breath alcohol. Comparison of blood and breath alcohol concentrations demonstrated significant differences in alcohol concentration [root mean square of 9.0 to 13.5 mg∕dL] that were attributable to both assay accuracy and precision as well as alcohol pharmacokinetics. A first-order kinetic model was used to estimate the contribution of alcohol pharmacokinetics to the differences in concentration observed between the blood, breath, and tissue assays. All pair-wise combinations of alcohol assays were investigated, and the fraction of the alcohol concentration variance explained by pharmacokinetics ranged from 41.0% to 83.5%. Accounting for pharmacokinetic concentration differences, the accuracy and precision of the spectroscopic tissue assay were found to be comparable to those of the blood and breath assays