Advances in flow extraction techniques: applications in forensic toxicology

Abstract

The goal of this work was to advance existing flow extraction techniques by incorporating repeatable fluid handling systems. The work contained in this dissertation describes the development of novel microscale extraction methods to isolate organic compounds from biological matrices encountered in forensic toxicology. Two new extraction techniques were developed; a sequential injection liquid extraction manifold and a fiber optic fluorescence detector for monitoring a heterogeneous immunoassay. The merits of each were compared to conventional methods in forensic toxicology.Conventional liquid solvent extraction was enhanced with sequential injection extraction. The sequential injection manifold took advantage of existing liquid extraction protocols and applied them to a new method of manipulating immiscible solvents in thin tubing, that combined the merits of flow injection extraction and sequential injection analysis. This method was used to extract both weakly basic and acidic drugs of therapeutic interest from urine.The merits of conventional solid phase extractions were shown with commercially available columns filled with a chemically modified solid phase to isolate the biotransformation products of cocaine. A novel flow cell designed to trap beads and monitor them with fiber optics, representing a combined extraction and detection system, was developed. An immunoassay using commercially available reagents was applied to this system to determine the feasibility of using flow injection renewable surface immunoassay in a quantitative immunoassay.Both of the techniques developed here require computer control, and enclosed and small volume samples. The advantages to such methods are that they can be readily automated and keep potentially hazardous solvents and samples away from the operator, and they produce less waste.