A novel approach to non-segmented flow analysis. Part 1: An experimental system

One of the most popular approaches to continuous-flow analysis in recent years has been the technique of flow-injection analysis (FIA) 1-3]. In essence, FIA relies on the mixing of a sample with specific reagents in a continuously flowing stream of carrier liquid while travelling to a detector. The detector monitors some property of the liquid which undergoes a change according to the extent of the selective reaction, which has occurred between the injection of the sample and its arrival at the detector. The principal advantage of this technique over the older, air-segmented continuous-flow analyser approach [4] is that the incompressibility of the non-segmented flow at the pressures commonly used in FIA (typically a few p.s.i.) allows the time interval between injection and detection to be reproduced with high accuracy. This, in turn, allows reaction products to be monitored without waiting for a steady-state to be reached, so permitting a high rate of sampling to be achieved and allowing chemistries in which reactions do not go to completion to be employed.