INDIRECT TIME-RESOLVED LUMINESCENCE DETECTION IN CAPILLARY ZONE ELECTROPHORESIS

Time-resolved luminescence of the terbium(III)-acetylacetone chelate has been used as an indirect detection method for capillary zone electrophoresis. Three different modes were investigated: dynamic quenching of the background signal by selected anions; ligand displacement of acetylacetone by other complexing agents; and electrophoretic displacement of acetylacetonate by anions in general. The latter two modes required the use of a post-capillary reactor; in this study, a coaxial flow-type reactor was used for this purpose. The results of dynamic quenching were good for the determination of nitrite, yielding detection limits of 3 . 10(-9) M (0.2 ppb). In addition, the feasibility of ligand and electrophoretic displacement was demonstrated. However, improvement of the post-capillary reactor and substitution of the xenon lamp by a focused laser beam is required to exploit fully the potential of the ligand and electrophoretic displacement options.