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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Simultaneous electrothermal vaporization and nebulization sources and improved methodologies for metallomic studies using ICP-MS

Arnquist, Isaac James 13 November 2012 (has links)
Both electrothermal vaporization (ETV) and nebulizer introduction sources offer unique advantages for inductively coupled plasma mass spectrometry (ICP-MS) analyses. A device for coupling the ETV and nebulizer was developed so that a quick switch from the nebulizer to the ETV (termed 'inline-ETV') could help gain additional information. The inline-ETV produced similar limits of detection (LODs) for most elements in both HNO₃ and HCl matrices compared to a conventional nebulizer or ETV. However, in a problematic matrix, isobaric interferences could exist that may not be accounted for in a typical nebulizer analysis. In a 1% HCl matrix, the LODs for ⁵¹V and ⁵³Cr--which are interfered with by ⁵¹ClO⁺ and ⁵³ClO⁺, respectively--improved 65- and 22-fold using the inline-ETV source compared to a typical nebulizer. In recent applications, ICP-MS has gained attention as a way of determining metal-protein associations. A novel broad-based methodology was developed to characterize metal-protein associations. The method utilized native gel electrophoresis for separation followed by electroblotting onto chemically-modified quartz membranes. The membranes were analyzed for metals using laser ablation ICP-MS. Modified membranes were shown to improve sensitivity compared to ablating a dried gel directly or using a commercially-available membrane. The coupling of separation by preparative ultracentrifugation and metal detection by ICP-MS was explored for metal-protein equilibrium determinations. This study characterizes the stoichiometry as well as apparent (K[subscript app]) and intrinsic (K[subscript int]) binding affinities for Cu-BSA, which was used as a model protein. K[subscript app] and K[subscript int] were determined at two different conditions, pH 9.53 and pH 7.93 in 100mM Tris buffer. The pH-independent K[subscript int] value at pH 9.53 agreed closely with literature values, while the value at pH 7.93 was approximately 2.5x larger. BSA undergoes a structural rearrangement between pH 7-9, and the generally accepted pH-dependency of protein tertiary structure may be responsible for the variations in the "intrinsic" binding constant. Overall, this study validates and shows the efficacy of combining preparative ultracentrifugation with ICP-MS detection for interrogating metal-protein associations while causing minimal equilibrium perturbations as a result of the separation and measurement processes. / text

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