Flow injection analysis
Encyclopedia
Flow injection analysis is an approach to chemical analysis that is accomplished by injecting a plug of sample into a flowing carrier stream. The principle is similar to that of segmented flow analysis
(SFA) but no air is injected into the sample or reagent streams.
) is injected into a carrier solution which mixes through radial and convection
diffusion
with a reagent
for a period of time (depends on the flow rate and the coil length and diameter) before the sample passes through a detector to waste. A Peristaltic pump
is the most commonly used pump in FIA instruments. FIA can, like SFA, be used for both medical and industrial analyses.
AutoAnalyzer
AutoAnalyzer is an automated analyzer using a special flow technique named "continuous flow analysis " first made by the Technicon Corporation. The instrument was invented 1957 by Leonard Skeggs, PhD and commercialized by Jack Whitehead's Technicon Corporation...
(SFA) but no air is injected into the sample or reagent streams.
Overview
FIA is an automated method in which a sample is injected into a continuous flow of a carrier solution that mixes with other continuously flowing solutions before reaching a detector. Precision is dramatically increased when FIA is used instead of manual injections and as a result very specific FIA systems have been developed for a wide array of analytical techniques.Principles of Operation
A sample (analyteAnalyte
An analyte, or component , is a substance or chemical constituent that is of interest in an analytical procedure. Grammatically, it is important to note that experiments always seek to measure properties of analytes—and that analytes themselves can never be measured. For instance, one cannot...
) is injected into a carrier solution which mixes through radial and convection
Convection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....
diffusion
Diffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
with a reagent
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
for a period of time (depends on the flow rate and the coil length and diameter) before the sample passes through a detector to waste. A Peristaltic pump
Peristaltic pump
A peristaltic pump, or roller pump, is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained within a flexible tube fitted inside a circular pump casing . A rotor with a number of "rollers", "shoes" or "wipers" attached to the external circumference...
is the most commonly used pump in FIA instruments. FIA can, like SFA, be used for both medical and industrial analyses.
Detectors
A flow through detector is located downstream from the sample injector and records a chemical physical parameter. Various different types of detector can be used For example:- colorimeterColorimeterFor articles on Colorimeter see:* Colorimeter * Tristimulus colorimeter...
- fluorimeter
- ion-selective electrode
- biosensors