Development of miniaturised flow systems for wet chemical applications

Abstract: This thesis is based on five papers addressing different types of analytical problems. In Papers I and II, the development of a miniaturised flow system is described as well as its use for monitoring compounds in industrial processes. In Papers III, IV and V, the development and practical use of a robust set-up is described, which is shown to be useful for a variety of chemical flow analyses for discrete samples, for example micro-volume extraction and titration.The miniaturised systems developed employ piston pumps yielding a controlled pulsed flow, giving rise to a detection response signal containing a wealth of information that can be related to important variables such as the amount of analyte and reaction kinetics. The pulsed flow also enhances the extraction rate in the monosegmented extraction system due to the efficient intrasegmental mixing. The pumps are used to introduce the samples and the reagents into a capillary. This effectively prevents the sample and reagent losses during the injection process that commonly occur in flow systems with valve injection. Typical volumes needed for this flow system for discrete samples range from 200 nl to 3 µl.The applicability of the miniaturised flow systems is illustrated by its successful use to monitor chlorine and phosphate, and to screen both partition coefficients (logKow) and dissociation constants (pKa).All the systems developed would be easy to automate.