1. For the past several years, one of the primary focuses of our research group has been the development of novel ion-exchange systems for the purpose of metal remediation from aqueous systems. Expanding on hints from Mother Nature, we chose to explore the metal chelation abilities of proteins and, in particular, their constituent amino acids. In order to simplify these ion-exchange systems, short-chain homopolymers consisting of repeating monomers of a specified amino acid residue have been used. These systems exhibit many of the characteristics for an ideal ion-exchanger – strong binding; fast, efficient release and structural stability. These biologically-based systems also have the added benefit of being environmentally friendly, unlike many traditional exchange systems which require harsh extraction agents. Developing Fluorescence- based Sensors Resonance energy transfer (RET) can be used to determine various characteristics of metal binding. RET involves the transfer of energy between a fluorescent donor and an acceptor molecule. The efficiency of the energy transfer is dependent on the distance between the molecules, which can be related to their spectroscopic properties. Questions? Email Brianna. briannawhite@mail.utexas.edu M+M+ M+M+ M+M+ M+M+ M+M+ M+M+ M+M+ Support The Bonded-Phase Ion-Exchange System Visit us! On the web: http://www.cm.utexas.edu/directory/james_holcombe/ In the Lab: Welch 3.240 and 3.238 Exploring a Combinatorial Approach Questions? Email Carina. cgunder@mail.utexas.edu High throughput screening Library of Oligopeptides U Determine what exclusively binds U Sequence peptide CGGDCCGDGC Synthesize polypeptide(s) and characterize uranium binding + Exposure to mixed metal solution M U CdCu High Throughput Screening of Combinatorial Libraries High Throughput Screening Techniques LED - stage illumination Polycapillary optic/ x-ray source Si Li detector Sample Micro-x-ray- fluorescence (MXRF) Fluorescence Microscopy ETV-ICPMS Bulk screening Based on fluorescence of bound species Non-destructive Single bead screening Quantitative elemental information Non-destructive UO 2 2+ in solution Absorption bands: 330-350nm, 390-440nm Emission bands: 470-570nm with max at 485nm, 510nm, 535nm, and 560nm Moulin, C. et al. Anal. Chem., 1995, 67, 348-353 Bell and Biggers. J. Molec. Spec., 1965, 18, 247-275 1mm Bead in metal solution Metal-bound bead in acid solution Metal solution to be quantified Bind metal Release metal Bulk/single bead screening Applicable for wide range of metals Non-destructive TackyDot™ slide to array beads Electrothermal vaporization inductively-coupled plasma mass spectrometry Questions? Email Ram. ramk@mail.utexas.edu Questions? Email Thomas. tk109400@mail.utexas.edu ETV-ICP-MS for Isobars and Isotopes Questions? Email Adam. adamrowland@mail.utexas.edu Creating Chemical-free Remediation Systems Column 3-electrode potentiostat Clean Effluent Stream Metal Recovery Stream valve Reference Electrode E applied Auxiliary Electrode An electrical potential is used to change the binding characteristics of the column. M n+ Oxidation Reduction M n+ Free metal can be bound and released by exposing the ligand to successive reduction and oxidation cycles. Flow Working Electrodes Counter Electrodes Scale up of the electrochemical reactor to practical size requires consideration of materials, geometry, operating conditions, and overall cost. First Vaporization Stage Second Vaporization Stage One problem with ICP-MS is elements of the same nominal mass (isobaric interference). ETV can be used to separate some problematic elements based on their differing volatilities. Rb and Sr can be separated to remove the isobar at mass 87. The time of flight design is able to offer excellent isotope ratio precision as a result of simultaneous ion extraction from the plasma. However, difficulties have been encountered with ratio accuracy. Factors that cause this and possible fixes are actively being researched. ICP-MS is the cutting edge technology for atomic spectrometry. It can offer part per trillion detection limits, over 5 orders of magnitude of linear response, and works for almost all elements in the periodic table. It uses an inductively coupled plasma (~8,000 K) as the ionization source. Our ICP-MS uses a time of flight system for mass analysis. Though many labs rely on solution nebulization for sample introduction, this is not always the best technique. It can be problematic for some matrices (e.g. salty solutions, organic solutions, and solids or slurries). An alternative is electrothermal vaporization (ETV). This uses a carbon tube to vaporize the sample before introduction to the ICP-MS. Vaporization temperatures of up to 3,000 o C can be achieved in a controlled manner. It can handle a wide variety of sample types, and generally has higher sample introduction efficiency than nebulizers. To ICP-MS Sample High Throughput Sample Introduction Multi-ETV system for rapid sample introduction, with all of the benefits of a graphite furnace. Coupled with the ICP-TOF, the periodic table can be analyzed every 40 seconds. This is 5 times faster than current techniques!