Comparison of a cross-flow and microconcentric nebulizer for chemical speciation measurements using CZE-ICP-MS

A standard cross-how nebulizer and commercially available micro-concentric nebulizer (MCN-100) have been compared for capillary zone electrophoresis (CZE) inductively coupled plasma mass spectrometry (ICP-MS) measurements. Metallothionein samples were separated and detected to characterize the performance of the two nebulizers for chemical speciation measurements. The MCN-100 offered improved sensitivity and lower detection limits compared to the cross-dow nebulizer, but provided slightly poorer resolution. The detection limit for Cd-114 in metallothionein solutions was 90 ng/g with the cross-flow nebulizer and 10 ng/g with the MCN-100 for similar to 4 nL injections. These values correspond to absolute detection limits of 360 fg Cd in the injected sample with the cross-flow nebulizer and 40 fg Cd for the MCN-100. Quantitation of Cd in metallothioneins (rabbit liver and horse kidney) with the use of a well-characterized rabbit liver metallothionein sample as the calibration standard is reported. Measured Cd concentrations agreed with results obtained by both graphite furnace atomic absorption spectroscopy (AAS) and solution nebulization ICP-MS.