OPTIMIZING DYNAMIC-RANGE FOR THE ANALYSIS OF SMALL IONS BY CAPILLARY ZONE ELECTROPHORESIS

Many applications of capillary zone electrophoresis (CZE) are for the determination of UV transparent ions. Indirect UV detection can be used for these analyses, but one problem with indirect detection is a limited dynamic range for analysis. A strategy for optimizing dynamic range for CZE analyses with indirect detection is described. Optimization involves chromaphore-electrolyte selection, concentration and wavelength optimization and tuning the electrolyte mobility through complexation. The strategy is illustrated for the analysis of aliphatic acids. We found that 2,6-naphthalenedicarboxylate is an ideal chromophore-electrolyte for aliphatic acid analysis. Through complexation with beta-cyclodextrin its mobility can be tuned to match the mobility of aliphatic acids. By optimizing detection wavelength and electrolyte concentration and mobility as little as 0.025 mg/l of aliphatic acids can be detected and up to 1000 mg/l can be quantitated. Under optimized conditions CZE can be used for trace analyses.