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ANALYTICAL AND NEUROCHEMICAL STUDIES WITH FLOW INJECTION ANALYSIS AND ELECTROCHEMICAL DETECTION: PART I. PULSED FLOW ELECTROLYSIS WITH THE RETICULATED VITREOUS CARBON ELECTRODE. PART II. ON-LINE DETERMINATION OF SECRETED CATECHOLAMINES FROM CULTURED ADRENAL CELLS (DESENSITIZATION, HYDRODYNAMIC MODULATION, IMMOBILIZED CELLS, THIN LAYER, POROUS)
Amperometric and coulometric reticulated vitreous carbon (RVC) detectors were constructed and evaluated for detection in flow injection analysis. These detectors offer a wide range of fraction conversion up to 100%. The flow rate dependency of the current was studied and compared with porous electrode theory. The precision, analytical range, band-broadening, and detection limits are comparable to that of other glassy carbon amperometric detectors. Pulsed flow electrolysis with the RVC electrode was developed for amperometry and voltammetry using lock-in amplification to measure the a.c. response which is independent of the large background current. Linearity and detection limits were determined and factors affecting the detection limits were investigated. The RVC electrode was shown to have rapid diffusion layer relaxation due to high conversion and thin layer electrolysis. Computer calculations of thin layer electrolysis were used to predict the mass transfer properties of the electrode and the results were compared with those of other electrode geometries. A new on-line system for studying the secretion of catecholamines from stimulated bovine adrenal cells in culture allows greater precision in kinetic measurements of the onset of secretion and the desensitization. The low-volume system uses flow injection analysis with which variable amounts of stimulant injected into the flowline pass through a packed bed of microbeads to which the cells are attached and the secreted catecholamines are electrochemically detected downstream. The low dispersion of the system provides low distortion of the secretory response and good detection limits. The desensitization in the presence of long-term stimulation with acetylcholine at room temperature was first order. Dramatic differences in the amount secreted and the recovery time of the cells were found at physiological temperature. Studies of secretion in the presence of nucleotides and varying concentrations of calcium revealed a depression of secretion in the presence of ATP and a minimum rate of desensitization in 1 mM calcium. More catecholamine was secreted in the absence of sodium than in its presence. The versatility of the technique for investigating desensitization and secretion due to one affector in the presence of another was demonstrated.
HERRERA, MICHELLE ELIZABETH, "ANALYTICAL AND NEUROCHEMICAL STUDIES WITH FLOW INJECTION ANALYSIS AND ELECTROCHEMICAL DETECTION: PART I. PULSED FLOW ELECTROLYSIS WITH THE RETICULATED VITREOUS CARBON ELECTRODE. PART II. ON-LINE DETERMINATION OF SECRETED CATECHOLAMINES FROM CULTURED ADRENAL CELLS (DESENSITIZATION, HYDRODYNAMIC MODULATION, IMMOBILIZED CELLS, THIN LAYER, POROUS)" (1985). Doctoral Dissertations Available from Proquest. AAI8517112.