Capabilities, limitations and applications of ATR-FTIR imaging

The dissertation describes the use of attenuated total internal reflection (ATR) infrared spectroscopy and imaging approaches for qualitative, semi-quantitative and quantitative analysis of challenging samples. Chapter 1 provides a background into the fundamentals of infrared spectroscopy and briefly covers sampling techniques available. Chapter 2 presents the use of ATR-FTIR spectroscopy to develop Principal Component Regression (PCR) models for quantitative analysis of kidney stone components. This study demonstrates that PCR models can provide more accurate prediction results than traditional Linear Least Square Regression (LLSR) method. Chapter 3 describes a comparative investigation using ATR and reflectance infrared microspectroscopic imaging techniques for the analysis of kidney stone cross-sections. Although both ATR and reflectance methods were able to provide chemical information about the components present, the ATR images displayed improved spatial resolution as well as photometric accuracy compared to reflectance images. Chapter 4 demonstrates the advantages of an ATR infrared microspectroscopic imaging technique for the analysis of polymer laminates. The results demonstrate that ATR offers improved spatial resolution, eliminates a variety of spectral competing processes, and requires minimal sample preparation relative to transmission measurements. Chapter 5 demonstrates the potential capabilities of ATR microspectroscopy for the detection of subvisible particulates in pharmaceutical industry. Ultimate detection limit of ATR-FTIR microspectroscopy was investigated. Chapter 6 summarizes the presented research and discusses future work.