Flow injection analysis (FIA) is a microchemical technique, developed in Denmark and the United States, for performing chemical analysis of sample materials in a flowing stream of carrier liquid. This computer compatible process has become the most popular type of flow analysis, and replaces manual methods using lab tubes and beakers. FIA is employed in monitoring industrial processes in the food, beverage and pharmaceutical industries; in agriculture; in environmental monitoring, such as testing water for contamination; and in life sciences.
In a flow injection system, the reagents, along with a carrier solution, are pumped through tubes in a continuous manner, mixing coils and the flow center in the detector. A reagent is a substance used in chemical reactions to detect, measure or produce other substances. A small sample of the substance to be tested in injected into the liquid solution where it combines with one or more reagents. The ensuing chemical reaction results in a color change that is measured in the detector. The entire process can be accomplished in approximately one minute with a much smaller sample than required in manual processes.
A wide range of flow injection analysis equipment is available. The simplest forms are inexpensive, manually operated units used to conduct inexpensive assays, or tests to determine the presence of a chemical or substance. More complex, completely automated systems are offered for biomolecule assays, such as determining hormone levels in blood. Automated systems range from affordable single chamber units to much more complex, multi-chamber configurations required for more difficult applications.
Flow injection analysis has become an inexpensive method to detect the presence of toxic substances in rivers or waste water. Testing near industrial sites is conducted in order to monitor if pollutants are being released. Existing FIA methods can detect the presence of ammonia, arsenic, mercury, cyanide, phosphate and nitrate in water.
Agriculture and forestry also make use of flow injection analysis to perform soil testing. On-site soil tests can be very helpful for site-specific crop management. Based upon the test results, growers can determine which nutrients may need to be replenished in order to obtain maximum crop yields. Forestry departments use FIA to determine the health of soil in state and national forests.
Flow injection analysis has been instrumental in helping pharmaceutical companies comply with strict regulations regarding quality control of drugs. Several samples are taken from each drug batch and tests are conducted to make certain the potency is stable; if a prescription calls for 250 mg of penicillin, it is important that every capsule contain exactly that amount. FIA is also used to test for vitamin, hormone and chemical levels in blood. Biologists use FIA to study live cells, monitor chemical processes and to study how the body produces antibodies when substances called antigens are introduced.
Flow injection analysis offers many advantages over traditional tube and beaker analysis. The procedure is inexpensive and quick, often producing results in under a minute. The automated flow of liquid provides a uniform testing environment and offers an additional level of protection to technicians when handling or testing toxic substances. The equipment is computer compatible as well, providing quicker analysis while limiting the data entry errors possible in manual testing.