New Approaches to Absorption Detection in Capillary Chromatography and Capillary Electrophoresis

Two new approaches for absorption detection in capillary columns are presented. They are applicable to columns as narrow as 10μm i.d. Both provide good sensitivity despite the very short optical pathlengths that are commonly available in commercial systems. The first involves irradiating the column along its axis rather than across the axis. The entire analyte zone can then participate in absorption. Gains up to 1000 fold can be expected. The second is a modification of laser‐excited fluorescence. The absorbing analytes, even though they do not fluoresce efficiently, can transfer their energy to a fluorophore added to the mobile phase. The secondary emission can be used to detect absorption in the nanomolar range.