| The goal of this research is to design, construct, and implement a spectroscopic system for measurement of reflected light intensities from a bulk-type ion selective optode membrane. It was hypothesized that a bulk-type ion selective optode membrane could be characterized in reflectance-mode measurements. Results of the reflectance-mode characterization experiments were compared directly to previously published absorbance-mode measurements.; There were three major outcomes of the project. A small volume (<50μL), reflectance-mode sensing system was developed using a novel spectrochemical flow-cell with 2 fiber-optic reflection probes (one emitting fiber and one detecting fiber) for reflection measurements. A plasticized PVC potassium-selective optode membrane consisting of a potassium-selective neutral ionophore, a neutral H+-selective chromoionophore, and lipophilic anion was incorporated into the reflectance-mode system and characterized in pH buffered solutions. Performance characteristics such as dynamic range, repeatability, reproducibility, response time, and selectivity measurements were comparable to the absorbance-based optode measurements.; The results of the study indicate the potential application of reflectance-mode spectroscopy and ion-selective optode membranes toward the measurement of ion concentrations in systems in which traditional absorbance-mode spectroscopy is not feasible. The results also indicate a need to continue to refine the system for measurements in biological media so that future work with in vivo applications will be possible. |
