Ultraviolet absorbance and inductively coupled plasma mass spectrometric detection for capillary electrophoresis—A comparison of detection modes and interface designs

Abstract

A comparison of ICP-MS and UV absorbance as detectors for capillary electrophoresis (CE) was performed. A high efficiency nebulizer (HEN) with cyclone spray chamber was found to yield detection limits in the low 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, and it was found that both methods gave similar detection limits and precision values for the separation, for both methods of detection. The use of a traditional concentric nebulizer as part of the CE–ICP-MS interface was evaluated and compared with the HEN. The optimum make-up buffer liquid flow rate was evaluated for the concentric nebulizer and detection limits for the lanthanide separation were calculated. Detection limits with the concentric nebulizer were not improved compared with UV detection, illustrating that the choice of nebulizer for the interface is of primary importance for improved analytical sensitivity. Attempts to use an oscillating capillary nebulizer as part of a CE–ICP-MS interface are also described.