ULTRAVIOLET ABSORBENCY AND INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETECTION FOR CAPILLARY-ELECTROPHORESIS - A COMPARISON OF DETECTION MODES AND INTERFACE DESIGNS

A comparison of ICP-MS and UV absorbance as detectors for capillary el ectrophoresis (CE) was performed. A high efficiency nebulizer (HEN) wi th cyclone spray chamber was found to yield detection limits in the lo w parts-per-billion range while UV detection gave detection limits in the parts-per-million range for the same separation of the lanthanides . Electrokinetic and hydrostatic methods of injection were employed, a nd it,vas found that both methods gave similar detection limits and pr ecision values for the separation, for both methods of detection. The use of a traditional concentric nebulizer as part of the CE-ICP-MS int erface was evaluated and compared with the HEN. The optimum make-up bu ffer liquid how rate was evaluated for the concentric nebulizer and de tection limits for the lanthanide separation were calculated. Detectio n limits with the concentric nebulizer were not improved compared with UV detection, illustrating that the choice of nebulizer for the inter face is of primary importance for improved analytical sensitivity. Att empts to use an oscillating capillary nebulizer as part of a CE-ICP-MS interface are also described.