INDIRECT FLUOROMETRIC DETECTION IN OPEN-TUBULAR CAPILLARY COLUMN CHROMATOGRAPHY

Reversed-phase open-tubular capillary (OTC) columns are prepared by cross-linking vinyl silicon gums on the inside of fused-silica capillaries. These columns are then provided with a low capacity of anion-exchange sites by dynamic modification with cetyltrimethylammonium bromide. Following anion-exchange chromatography, common anions are detected by indirect fluorescence detection, using micromolar salicylate as the eluent and the visualization agent, and a UV laser as the excitation source. Unmodified reversed-phase OTC columns are used for the separation of various alcohols. These alcohols are detected by indirect fluorescence detection, using 2,7-dichlorofluorescein as the fluorescent reagent and a visible laser as the excitation source. The small dimensions (13-15 μm I.D.) of the OTC columns and good stability of the fluorescence background (dynamic reserve ≥ 103) allow femtogram (attomole) amounts of both types of analytes to be detected. The detectable concentrations are in the 30-nM range. © 1990.