The need for sensitive and selective detectors in supercritical fluid chromatography (SFC) is particularly evident since SFC can be used to analyze classes of compounds that are not readily amenable to either gas chromatography (GC) or liquid chromatography (LC). These compounds include species that are nonvolatile or thermally labile and , in addition, contain no chromophore that can be used for spectrophoto detection. The objective of this research is therefore to interface selective chemilumninescent detectors with SFC in the sensitive detection of nitrogen- and/or sulfur containing compounds. The chemiluminecent nitrogen detector (CLND), a gas-phase detector which is specific for nitrogen-containing compounds, was first evaluated as a detector for use with capillary SFC. The potential use of the CLND for food flavor and petroleum samples was demonstrated. In addition to equimolar nitrogen response, the CLND showed good sensitivity and large linear dynamic range. Minimum detectable quantity (MDQ) was 60 pg of nitrogen with a linear range of over 3 orders of magnitude. Nitrogen to carbon selectivity of 105 was obtained. Capillary SFC with simultaneous flame ionization and chemiluminescent detection was also demonstrated. The second portion of the research investigated the CLND for packed column SFC with methanol modified CO2. The only modification made in the CLND for packed column SFC is the pyrolysis furnace. The CLND and UV were used to interface with SFC via a post-column split. Methanol-modified CO2 was also demonstrated to be compatible with the CLND even with a high mobile phase flow rate. The use of pressure and modifier programs appears to be feasible as is evidenced by the baseline studies which have been performed, as well as by the applications demonstrated. The last portion of the research focused on the evaluation of a new generation sulfur chemiluminescent detector (SCLD), which is also a gas-phase detector, with packed column SFC using both pure and methanol modified CO2. The minimum detectable quantities were determined to be 2.6 pg or 14 pg sulfur for mobile phase employing pure CO2 or 8% methanol modified CO2 respectively. The evaluation study also showed excellent selectivity and linearity, as well as day-to-day repeatability. The capabilities of the SFC-SCLD system for sulfur speciation and detection of thermally labile pesticides and polar sulfonamides, as well as petrochemical samples were presented. / Ph. D.

One of the most relevant group of toxicologically significant compounds in beer are N-nitrosamines. In this thesis, the attention was paid especially on non-volatile nitroso compounds whose concentrations in beer, a chemical structure, and a biological effect has not been known yet. For the reason of the lack of knowledge regarding this compound group, the method for their sensitive detection by chemiluminescence detection after gas chromatographic separation was developed. This method permits a classification of detected nitroso compounds to different groups (N-nitroso, C-nitroso, and combination of C-nitroso and nitro) and distinguish them from interferences. The method is based on recording of a pyrolytic profile of each chromatographic peak, the profiles are then processed by discriminant analysis. The method has been developed for finding and structural identification purposes of these unknown compounds. Its application on an artificially nitrosated beer sample, together with gas chromatographic tandem mass spectrometric analysis, led to structural identification of several representatives of nitroso compounds. Sensory active compounds in this thesis are represented by carbonyl compounds and fatty acids. Carbonyl compounds - furfural and hydroxymethylfurfural - were used during the development...