APPLICATION OF MICROPOROUS MEMBRANES TO CHEMI-LUMINESCENCE ANALYSIS

A novel approach to reagent introduction into flowing streams is accomplished by using a microporous membrane to separate a reagent reservoir from an analyte stream. Reagent addition rates as low as a few μL/min are possible and can be controlled by the membrane porosity, membrane surface area, concentration of reagents in the reagent reservoir, applied pressure gradient. The reaction zone is probably near, but not confined to the membrane surface; reagent concentrations in the reaction zone appear to be one tenth of that in the reagent reservoir. With Co(II) as the analyte, efficient rinsing of the cell is limited by adsorption at the membrane surface, but can be improved if EDTA is present in the rinse solution. Sensitivity is maximized for analyte solutions of pH 7-9. Determinations of Co(II) using luminol have a detection limit of about 10-10 M (10 part per trillion); typical precision is ±3%. © 1979, American Chemical Society. All rights reserved.