Portable Flow-Injection Systems for Field Testing

One of the pronounced trends in the development of instrumentation for chemical analysis in recent years is the design of analytical instruments that makes possible their operation in situ in the direct vicinity of the material to be analysed. The objectives are to allow operation in rugged areas without electricity or consumables, and to limit or even eliminate difficult problems associated with sampling, transport of the samples, and sample pretreatment. This approach is the basic for the intensive developments in areas of chemistry such as in process analysis, in vivo analysis, and field analysis.Field analysis is being developed particularly for environmental, military, industrial and agriculture aims. For these purposes, various types of instrumentation designs are utilized in order to miniaturize the analytical measuring device. The rapid technological progress in material science, electronics and optoelectronics allows the constrrction of portable chromatographs, mass spectrometers, FT-IR, and X-ray spectrometers. The classical methods of wet analysis have also been used in procedures based on various systems with layers of solid reagents. Specific field tests dependent on immunochemical reactions have replaced with great success the more complex chromatographic method.Is there in this race a place for field devices based on flow-injection analysis (FIA) methodology? FIA has been widely accepted in analytical laboratories using wet procedures, and there has been an increasing number of applications reported over recent years in process analysis. The miniaturization of fluid transport systems for liquids and gases, and also detectors, is now in advanced stage of development for use in field portable instrumentation. The use of appropriate biocatalytic and immunochemical steps provides the means for obtaining sufficient selectivity, and thus eliminates sample pretreatment steps. Appropriately designed FIA systems can be operated with very small sample volumes in closed-loop systems allowing re-circulation of reagents.FIA systems also allow the simple dosing of small volumes of sample and reagent solutions without additional accessories, which are troublesome in field usage. Thus, we can conclude that field FIA systems in comparison with solid reagent systems are especially useful for environmental analytes, both gaseous and liquid, which normally would require pre-concentration of trace quantities from large volumes of the original material or separation from complex matrices.