Flow injection analysis
Flow injection analysis (FIA) is an approach to chemical analysis. It is accomplished by injecting a plug of sample into a flowing carrier stream.[1][2][3] The principle is similar to that of segmented flow analysis (SFA) but no air is injected into the sample or reagent streams.
Overview
FIA is an automated method of chemical analysis in which a sample is injected into a flowing carrier solution that mixes with reagents before reaching a detector. Over past 30 years, FIA techniques developed into a wide array of applications using spectrophotometry, fluorescence spectroscopy, atomic absorption spectroscopy, mass spectrometry, and other methods of instrumental analysis for detection. Based on computer control, FIA evolved into Sequential Injection and Bead Injection which are novel techniques based on flow programming. FIA literature comprises over 22,000 scientific papers and 22 monographs.[4]
History
Principles of Operation

A sample (analyte) is injected into a flowing carrier solution stream that is forced by a peristaltic pump. The injection of the sample is done under controlled dispersion in known volumes. The carrier solution and sample then meet at mixing points with reagents and react. The reaction time is controlled by a pump and reaction coil. The reaction product then flows through a detector. Most often, the detector is a spectrophotometer as the reactions usually produce a colored product. One can then determine the amount of an unknown material in the sample as it is proportional to the absorption spectrum given by the spectrophotometer. After moving through the detector, the sample then flows to waste.
Detail of Sample Dispersion
When a sample is injected into the carrier stream it has the rectangular flow. As the sample is carried through the mixing and reaction zone, the width of the flow profile increases as the sample disperses into the carrier stream. Dispersion results from two processes: convection due to the flow of the carrier stream and diffusion due to a concentration gradient between the sample and the carrier stream. Convection of the sample occurs by laminar flow, in which the linear velocity of the sample at the tube’s walls is zero, while the sample at the center of the tube moves with a linear velocity twice that of the carrier stream. The result is the parabolic flow profile, before the sample passes through a detector to a waste container. [5]
Detectors
A flow-through detector is located downstream from the sample injector and records a chemical physical parameter. Many types of detector can be used such as:[5]
Industrial Applications
Agriculture
Flow injection analysis can be used to test soil, fertilizer, water, plant tissue samples, and many other matrices. The compounds analyzed are typically inorganic molecules, including nitrate, phosphate, chloride, ammonia, and more. Possibly the most widely conducted soil tests are those done to estimate the plant-available concentrations of plant nutrients, in order to determine fertilizer recommendations in agriculture. Other soil tests may be done for engineering (geotechnical), geochemical or ecological investigation.
Environmental
Common uses include ammonia analysis, anion analysis (chloride, nitrate/nitrite, phosphate) and hexavalent chromium.
Marine
Flow injection techniques have proven very useful in marine science for both organic and inorganic analytes in marine animal samples/seafood. Flow Injection methods applied to the determination of amino acidss (histidine, L-lysine and tyrosine), DNA/RNA, formaldehyde, histamine, hypoxanthine, polycyclic aromatic hydrocarbons, diarrheic shellfish poisoning, paralytic shellfish poisoning, succinate/glutamate, trimethylamine/ total volatile basic nitrogen, total lipid hydroperoxides, total volatile acids, uric acid, vitamin B12, silver, aluminium, arsenic, boron, calcium, cadmium, cobalt, chromium, copper, iron, gallium, mercury, indium, lithium, manganese, molibdenum, nickel, lead, antimony, selenium, tin, strontium, thallium, vanadium, zinc, nitrate/nitrite, phosphorus/phosphate and silicate. [6]
Research and Education
Experiments
An experiment that is used in analytical chemistry lab courses to familiarize students with FIA is the determination of phosphate by flow injection analysis. The experiment involves calibrating an FIA system, optimizing the system for detection of phosphate and finding the amount of phosphate in an unknown sample.
See also
References
- ^ Xu, Weihong; Sandford, Richard; Worsfold, Paul; Carlton, Alexandra; Hanrahan, Grady (2005). "Flow Injection Techniques in Aquatic Environmental Analysis: Recent Applications and Technological Advances". Critical Reviews in Analytical Chemistry. 35 (3): 237. doi:10.1080/10408340500323362.
- ^ Tyson, Julian F. (1985). "Flow injection analysis techniques for atomic-absorption spectrometry. a review". The Analyst. 110 (5): 419–569. Bibcode:1985Ana...110..419T. doi:10.1039/an9851000419. PMID 4025835.
- ^ Anastos, N.; Barnett, NW; Hindson, BJ; Lenehan, CE; Lewis, SW (2004). "Comparison of soluble manganese(IV) and acidic potassium permanganate chemiluminescence detection using flow injection and sequential injection analysis for the determination of ascorbic acid in Vitamin C tablets". Talanta. 64 (1): 130–4. doi:10.1016/j.talanta.2004.01.021. PMID 18969577.
- ^ Ruscika, Jarda. "Flow Injection Tutorial". www.flowinjectiontutorial.com. Retrieved 2016-03-28.
- ^ a b Trojanowicz, M. (2000). Flow injection analysis : instrumentation and applications. World Scientific.
- ^ C., Yebra-Biurrun, M. (2009). Flow injection analysis of marine samples. New York: Nova Science Publishers. ISBN 9781608765669. OCLC 593305526.
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5. J. Ruzicka Flow Injection Analysis. Tutorial 2015 Edition www.flowinjectiontutorial.com
- Trojanowicz, Marek (2000). Flow injection analysis: instrumentation and applications. Singapore: World Scientific. ISBN 981-02-2710-8.
- Hansen, Elo Harald; Růžička, Jaromír (1988). Flow injection analysis. New York: Wiley. ISBN 0-471-81355-9.
- Martínez Calatayud, José (1996). Flow injection analysis of pharmaceuticals: automation in the laboratory. Washington, DC: Taylor & Francis. ISBN 0-7484-0445-7.
- Pacey, Gil E.; Karlberg, Bo (1989). Flow injection analysis: a practical guide. Amsterdam: Elsevier. ISBN 0-444-88014-3.
- Cerdà, Víctor; Ferrer, Laura; Avivar, Jessica; Cerdà, Amalia (2014). Flow analysis: A practical guide. Amsterdam: Elsevier. ISBN 978-0-444-62606-6.
- Cerdà, Amalia; Cerdà, Víctor (2009). An introduction to flow analysis. Mallorca: Sciware.