OPTIMIZATION AND EVALUATION OF THE PERFORMANCE OF ARRANGEMENTS FOR UV DETECTION IN HIGH-RESOLUTION SEPARATIONS USING FUSED-SILICA CAPILLARIES

The evaluation of arrangements for UV measurements in fused-silica capillaries as applied in, e.g., high-performance capillary electrophoresis, capillary liquid chromatography and hydrodynamic chromatography is described. The various designs are characterized with respect to sensitivity, noise, linearity, contribution to the peak width and sensitivity to refractive index effects. Some guidelines are formulated, based on theoretical and experimental observations, in order to maximize the performance. A cell with a focusing lens in front of the capillary resulted in a higher sensitivity and linear range than a cell with an adjustable aperture width. With the U-cell, having a design which is comparable to Z-shaped cells and having a longer longitudinal light path, a substantial increase in signal-to-noise ratio was achieved. Some applications of the UV cells are shown.