The determination of the total element content in a biological sample or system has become outdated in recent years. Trace element speciation has become increasingly important in environmental, nutritional, biological and medical sciences. Speciation of an element includes the identification of the compound to which the element is bound and the quantification of the element associated with the particular compound. Various separation techniques coupled with elemental detection techniques have been used for the speciation of trace elements. Capillary electrophoresis (CE) has been under development for more than a decade. It offers rapid separation with high separation efficiency and resolution, and it also requires very small sample size which makes it especially attractive for biological sample analysis. Currently, inductively coupled plasma mass spectrometry (ICP-MS) is one of the most sensitive elemental detection techniques, with detection limits down to part per trillion levels. Research on interfacing CE and ICP-MS has been in progress during the past five years. Different nebulizers have been used for the CE-ICP-MS interfaces. In this research project, two nebulizers, a concentric and an ultrasonic (USN), are used as CE-ICP-MS interfaces. Metallothioneins (MTs) are used to characterize and optimize the interfaces. Metallothionein isoforms are separated and determined by the CE-ICP-MS. With the concentric nebulizer interface, negative pressure had to be applied at the inlet of the CE capillary in order to maintain the separation resolution. No suction occurred in the USN interface. Signal intensity was improved with the USN interface compared to the concentric nebulizer; however, signal-to-noise ratio was only marginally improved owing to the higher noise level. Protein-bound zinc in human serum albumin and $\alpha\sb2$-macroglobulin was determined with the USN interface. In addition to being a model protein for characterization of the interfaces, metallothionein is also one of the major zinc-binding proteins that is of interest in this project. Separation and determination of metal-contents of MTs in different buffers by CE-ICP-MS was examined with on-line photodiode array detector. Analysis of serum proteins by CE-ICP-MS was investigated. The possibility of ICP-MS detection of protein-bound zinc in albumin and $\alpha\sb2$-macroglobulin is demonstrated. Zinc isotope ratio measurement of these proteins is also attempted, however, the signal sensitivity available from current instrumentation and interface does not ensure precise and accurate measurement. Further improvement of the interface and instrumentation is necessary.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-2841 |
| Date | 01 January 1997 |
| Creators | Lu, Qinghong |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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