DEVELOPMENT OF PHOTOCHEMICALLY INITIATED DIRECT AND INDIRECT LUMINESCENCE DETECTION METHODS FOR LIQUID CHROMATOGRAPHY (LC) AND STUDY OF AROMATIC SULFONATES AND PHOSPHOLIPIDS USING REVERSED PHASE ION-PAIR LC-MASS SPECTROMETRY
The first project is development of a 5.5 µL spiral micro-flow chemiluminescence (CL) cell that allows the rapid mixing of CL reagent and analyte and simultaneous detection of the emitted light for flow injection (FI) using a 25 µL/min flow rate for luminol and a 50 µL/min buffer carrier flow rate. The detection limit of 1.5 µM achieved by using a spiral flow cell is 24 times lower than that obtained from a conventional FI system with a premixing tee and a straight 12 µL flow cell. This luminol FI method is applied to the enzymatic determination of L-lactate from 5–50 µM using polyethyleneglycol-stablized lactate oxidase. The second project is development of a quinine-sensitized photo-oxidation and quenched CL detection method for phenols using FI and LC. This method is based on the decrease of light emission from the luminol CL reaction due to the photo-oxidation of phenols that scavenge the photogenerated reactive oxygen species. On-line photo-oxidation is achieved using a coil photo-reactor made from FEP tubing coiled around a mercury UV lamp. This method is applied for the FI determination of ten phenolic compounds, mostly nitro- and chloro-phenols, and the LC determination of phenol, 4-nitrophenol and 4-chlorophenol with detection limits of about 1 µM. The third project is development of an indirect fluorescence (FL) detection method via the shielding effect on the UV-photolysis of 2-phenylbenzimidazole-5-sulfonic acid (PBSA). Compounds that have a strong UV absorbance at 217 nm and/or are reactive toward the photogenerated oxygen species can possess such a shielding effect. This method is applied for both the FI determination of thirteen aromatic compounds, mostly non-fluorescent nitro compounds, and the LC determination of salicylate, nitrofurantoin, 4-nitroaniline, 2-nitrophenol, and 4-nitrophenol with detection limits of about 0.2 µM. The fourth project is separation of ionic organic compounds by reversed phase ion-pair LC with MS detection. tert-Octylamine (TOA) is studied as a new more volatile ion-pairing agent for separation of aromatic sulfonates. The separation results are compared with those obtained from NH4OH, dihexylamine, and tri-n-butylamine. TOA is the preferred ion-pairing agent as compared to NH4OH for the gradient separation of phospholipids.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:spiral micro flow cell injection luminol chemiluminescence hydrogen peroxide l lactate photo oxidation quinine photosensitizer phenols liquid chromatography indirect fluorescence detection shielding effect nitro aromatic compounds non fl
Date of Publication:01/01/2003