| The high efficiency of capillary electrophoresis (CE) was combined with the element specificity and low detection limits of inductively coupled plasma mass spectrometry (ICP-MS) for rapid elemental speciation. An external sheath flow interface was developed to provide an efficient method for interfacing capillary electrophoresis with the inductively coupled plasma. The sheath interface provides control over the nebulizer induced laminar flow in the separation capillary allowing the tradeoff between separation efficiency and analysis time to be selected. In this manner, the conditions can be optimized for the rapid separation of positive and negative ions in one injection or high resolution analyses of metal cations.; The effect of laminar flow on CE resolution and ICP-MS sensitivity was characterized. Mathematical models were developed to include the effects of laminar flow and predict both migration times and peak widths in the separation capillary under a variety of conditions.; The desolvation, vaporization, atomization, ionization and excitation of sample in the ICP have been difficult to study previously because conventional nebulizers introduce millions of drops with widely varying sizes into the ICP each second. A monodisperse dried microparticulate injector (MDMI), developed by French and co-workers at the University of Toronto Institute for Aerospace Sciences, was used to introduce individual, monodisperse droplets of sample into the ICP reproducibly. A series of experiments using laser light scattering, emission and saturated laser fluorescence images of atom and ion clouds in the ICP are described. A large, high power laser beam is used to illuminate the ICP. A gated, intensified charge coupled device (iCCD) detector, mounted on the focal plane of an imaging spectrometer was used to acquire the image of a complete atom or ion cloud as a function of height and time in the ICP. The effect of the NaCl matrix on droplet desolvation was studied. Using integrated emission and fluorescence and emission images, the total numbers of atoms and ions as well as the fraction excited can be studied in the presence and absence of the matrix elements. Using this system, the effects of matrices on the fundamental processes which occur in the ICP can be investigated with previously unattainable clarity. |
