I. Effect of an anionic polymer on the separation of cationic molecules by capillary electrophoresis. II. Off-line and on-line photochemical reaction of aromatic nitro compounds with detection by molecular spectroscopy and mass spectrometry

This research represents the development of a method for the separation of cationic compounds using capillary electrophoresis (CE) and the study of the photolytic and photocatalytic degradation of nitro compounds. The first project involved the separation of representative quaternary amines, alkali metals in the presence of choline, as well as alkyl-substituted ethylenediamine polyamines using CE with polymer additives and conductivity detection. Definite changes in the electrophoretic mobility of quaternary amines were reported using 0.03–0.08% poly (sodium 4-styrenesulfonate) as a buffer additive. Adsorption of poly-L-glutamic acid onto the capillary resulted in better resolution of the polyamines.; The remaining projects deal with the photolytic and photocatalytic oxidation of nitrophenol isomers, nitrotyrosine, and nitro drugs (dantrolene, nitrofurantoin, and furazolidone). The UV-Vis data showed that nitro compounds exhibited significant degradation within 10 min of off-line irradiation, especially in the presence of TiO₂. The decomposition of aqueous solutions of nitro compounds yielded nitrate, nitrite, and phthalate as separated by CE. Nitrotyrosine degraded in a shorter time than tyrosine and phenylalanine and its major photodegradation product was identified by MS to be dopamine (DOPA).; The combination of on-line photochemistry with fluorometric detection permitted the determination of nitrophenols, nitrotyrosine, and nitro drugs at levels less than 100 ng/L. The possibility of a fluorescent signal even at a short photolysis time (∼3 min) was attributed to the elimination of the nitro group and the formation of highly fluorescent products such as phenol. The advantage of the commercially available photocatalytic TiO ₂ reactor over the open-tubular Teflon reactor that is usually used with on-line photochemistry was apparent for nitrophenols.; The photochemical activity of nitro drugs and nitrophenols was investigated using flow injection (FI) and liquid chromatography mass spectrometry (LC/MS). In the case of nitrophenol isomers, either the 2- or 4-nitrophenol could be distinguished depending on the type of photoreactor. The mass spectra of nitro drugs after on-line photolysis showed improved total ion current as well as valuable qualitatively identifying information.