IN-COLUMN VERSUS ON-COLUMN FLUORESCENCE DETECTION IN CAPILLARY ELECTROCHROMATOGRAPHY

Capillary electrochromatography (CEC) is a technique that uses electro osmotic flow for the propulsion of the mobile phase in liquid chromato graphy. Employing packed fused-silica capillaries, fluorescence detect ion is possible in a packed section of the separation capillary (in-co lumn detection) or in an emptied section (on-column detection). These two detection modes were compared with each other with respect to dete ction limit, precision and instrumental band-broadening effects. By mo nitoring plug-like solute zones it is shown that with in-column detect ion the signal noise is dependent on the signal height, whereas with o n-column detection the signal noise is independent of the signal heigh t.