Flow Injection Analysis in Industrial Biotechnology

Abstract

Flow injection analysis (FIA) is an analytical chemical continuous flow (CF) method which, in contrast to traditional CF procedures, does not rely on complete physical mixing (homogenization) of the sample and the reagent(s) or on attaining chemical equilibria of the chemical reactions involved. Exploiting controllable dispersion of the injected sample within the reagent‐containing carrier stream and strictly reproducible timing of all events taking place, it is based on measuring transient signals, which not only implies very high sampling rates but also, and most importantly, permits implementation of a number of novel methodologies that are not feasible when performed under batch conditions or by conventional CF procedures. Demonstrated for selected bioanalytical and technological applications encompassing cellular and enzymatic assays as well as monitoring of culture media, the principles and operational characteristics of FIA are first outlined, and then its downscaled/miniaturized sequels, that is, sequential injection analysis (SIA) and lab‐on‐valve (LOV), are detailed. Thus, in SIA the sample and reagents are, via the use of a multi‐position valve and an attached syringe pump operated under full programmable control, aspirated sequentially and then propelled forward allowing the sample and reagent(s) to be intermixed and, if called for, subjected to appropriate treatments before analyte detection. This infers that, merely minute sample/reagent volumes are consumed, hence leading to generation of small amounts of waste. In LOV this downscaling is taken further by using a small monolithic structure within which all sample manipulations and ultimate analyte detection under programmable control can be effected. Even bead materials with different surface groups/characteristics, including live cells, can be handled and utilized as demonstrated. Because the syringe pump in SIA and LOV can be used for accurately aspirating, propelling or even stopping the flow, these modi operandi allow fully to exploit the interplay between the kinetics and the thermodynamics of the chemical reactions involved, so that there are no restrictions whatsoever as to the chemistries that can be implemented, even if they entail multistep reactions. Representative bioanalytical examples of this interplay are presented.

Point-of-Care Platforms

“…Because in many cases optical POCT platforms are used in combination with microfluidics, flow injection analysis is used, which for many years has been known for immunoanalyses (32,33). Flow injection analysis has been reviewed in several publications (34)(35)(36)(37). References 38-40 review special applications to clinical and pharmaceutical analysis.…”

Automated Bioanalyzer Based on Amperometric Enzymatic Biosensors for the Determination of Ethanol in Low-Alcohol Beers

“…However, the application of this kind of system at an industrial production level is still not well established due to the lack of continuous detection devices with correction capacity allowing monitoring and control of processes. Real-time monitoring in the production line demands that the analyzer system by itself would be able to scrutinize the obtained results and perform recalibrations, if needed, at required time intervals [28].…”