|Title||Centrifugal Partition Chromatography, Microfabrication, and a Smartphone-based Detection Platform: Analytical Chemistry from Preparative-scale Separation to Micro-scale Analysis|
|Year of Publication||2017|
|University||Oregon State University|
Analytical chemistry is an area of chemistry primarily focused on the study and use of instruments for separation, identification, and quantification of an analyte of interest. Specifically, separation science within analytical chemistry often refers to the process of dividing mixtures into their small component parts based on differences in their physical and chemical properties; this can be preparative or analytical chromatography. With advances in microfabrication and microfluidic technologies in recent years, miniaturization of the analytical process has been a priority. However, traditional preparative scale separation processes are equally impactful because of their use for isolating components on a greater scale to allow for isolation of highly pure products for further use. These traditional preparative separation methods, when employed in natural product extraction and isolation, can yield a highly purified product in enough quantity to perform further studies. The first research chapter describes the use of centrifugal partition chromatography (CPC) for the preparative-scale isolation and purification of xylindein from the fungi, Chlorociboria aeruginosa. Solvent system compositions for xylindein isolation using CPC were explored, resulting in a new solvent system appropriate for purification of xylindein. The separation technique was optimized and used to isolate naturally sourced xylindein in amounts suitable for further study. Though preparative scale separations are useful and impactful for natural product extraction, interest in miniaturization and microfluidic technologies has grown tremendously in the past decades owing to their benefits in many fields of applications. In the following chapter, a novel approach to fabrication employing a high-speed CO₂ laser for etching was used for rapid fabrication of polymethyl methacrylate-based microfluidic devices. The fabrication method provides a simple approach for the production of microfluidic chips, and offers the versatility needed to achieve different designs and features for a wide variety of applications. The microfluidic chips fabricated using this technique were used to perform on-chip electrophoresis with rhodamine B as a standard test dye. The electropherograms obtained from the fabricated microchips were reproducible and comparable to a polymethyl methacrylate (PMMA) standard chip. Microfluidic devices can integrate the entire analytical process, including sample handling, preparation, reaction, separation, and detection, onto a single chip. The system also allows for size reduction of instrumental components, and enhances the development of portable analytical tools for field-testing applications. The final section of this work includes the utilization of a smartphone as the detection platform for a well developed, relatively inexpensive, commercially available clinical chemistry assay as a model for rapid and inexpensive field-portable diagnostic testing. It was possible to quantify glucose over its clinically important concentration range (30–515 mg/dL) with good linearity (R² = 0.9994, n = 5). Data collected using the iPhone 4 and canine serum samples were in agreement with results from the instrumental “gold standard” (Beckman Coulter AU480 Chemistry System). Presented herein are applications in analytical chemistry and separation science. Preparative scale isolation of naturally extracted xylindein was achieved in good yield using CPC; a novel fabrication technique for a polymeric microfluidic device was developed and used for on-chip CE; the applicability of smartphone technology for glucose detection was demonstrated for use as a portable analytical tool. Finally, though analytical chemistry is a broad field, the methods and techniques described within this dissertation have contributed to furthering science and knowledge in the subfields of preparative scale separations, microfabrication and microfluidic technology, and smartphones as detectors for clinically relevant analytes.