MODIFICATIONS OF A HPLC UV-VIS DETECTOR FOR ON-COLUMN DETECTION IN CAPILLARY ELECTROPHORESIS

The mechanical and optical modifications carried out to adapt an High Performance Liquid Chromatography (HPLC) UV-Vis detector for on-column detection in Capillary Electrophoresis are reported. The new cell permits the repositioning of the separation capillaries into the light beam with a reproducibility of +/- 2 mum. The beam intensity obtained by the new optics is sisfold bigger than that obtained with the original one. The detection limit for ethyl benzene (the solute tested) is in the low picogrammes range (4,6-12 pg depending on the capillary internal diameter). The detection lineary is better than three orders of magnitude in the different capillaries tested (internal diameters of 50, 75 and 100 mum).