Investigating Novel Methods for Using Water in Analytical Extractions and Separations
Abstract
This thesis describes the development of novel methods for using water in analytical extractions and separations to reduce organic solvent use, decrease environmental impact and lower operation costs. The first area of exploration is the sample preparation of pharmaceutical formulations, which is conventionally time consuming and organic solvent intensive. Here, subcritical water extraction (SWE) is employed as an inexpensive and environmentally friendly technique to rapidly extract active pharmaceutical ingredients from commercial formulations using only water as the solvent. Quantitative recoveries are obtained from different sample forms including capsule contents and intact tablets, the latter of which demonstrates the potential of SWE to minimize sample handling. Overall, SWE is shown to be a potentially viable method for fast, inexpensive and green sample preparation of pharmaceuticals in both capsule and tablet form. Next, the coating properties of a water stationary phase in a capillary supercritical fluid chromatography (SFC) system are investigated. It is shown that the water phase is uniformly deposited inside stainless steel (SS) columns of varying length and i.d., resulting in a consistent water coverage per area. Hydrofluoric acid etching is explored to increase water stationary phase volume, where prolonged etching of the inner capillary wall served to double water volume and analyte retention. Results indicate that etching could be a useful method to control the volume of water in the column while still maintaining good chromatographic peak shapes and plate heights. Finally, the utility of a water stationary phase is expanded by demonstrating the use of SS particles as a novel support for this phase in a packed column SFC format. Compared to analogous separations employing a water stationary phase coated onto a SS capillary column, the packed column gives faster separations and larger analyte retention factors with comparable plate heights and good peak shapes. Further, the increased volume of stationary phase in the packed column leads to a larger sample capacity. Several applications of the packed column system are examined, and the results indicate that it is a useful alternative to the capillary column mode, particularly where analyte loads or sample matrix interference is a concern.
Description
Keywords
Chemistry--Analytical
Citation
Murakami, J. N. (2015). Investigating Novel Methods for Using Water in Analytical Extractions and Separations (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/26632