Continuous Flow Analysis and Discrete Analyzers

LCGC North America

LCGC North America, LCGC North America-07-01-2008, Volume 26, Issue 7
Pages: 596

In continuous flow analysis (CFA), a sample is injected into a flowing carrier solution passing rapidly through small-bore tubing. The sample is mixed with a reagent, which reacts with the sample to develop a color and determine the sample concentration. The use of carefully controlled flow conditions ensures that the color development reaction is reproducible, so that the color measurement need not wait until the reaction has gone to completion.

In continuous flow analysis (CFA), a sample is injected into a flowing carrier solution passing rapidly through small-bore tubing. The sample is mixed with a reagent, which reacts with the sample to develop a color and determine the sample concentration. The use of carefully controlled flow conditions ensures that the color development reaction is reproducible, so that the color measurement need not wait until the reaction has gone to completion.

CFA and discrete analyzer demand industry

There are several technologies of CFA such as segmented flow analysis (SFA), which uses turbulent flow conditions that allow for complete sample dispersion. Other technologies include flow injected analysis (FIA) and sequential injection analysis, which uses laminar flow existing in the narrow-bore tubing to mix with the reagent to eliminate the need for air bubble partitioning.

In contrast to CFA, discrete analyzers keep sample separate throughout the testing process, dispensing precise amounts when required. Rotating individual cuvettes through the instrument instead of releasing the sample in a continuous stream cuts down on reagent waste, and can produce hundreds of results per hour.

CFA and discrete analyzers are used in environmental applications for measuring analytes like ammonia, chloride, nitrite, phosphate, etc. The systems also are used in food and beverage, chemical testing, and pharmaceutical laboratories. Although CFA is a well-established technique for industrial applications, the prospect of cutting testing and consumable costs, along with the ease of operation have prompted many laboratories to transfer methods from CFA to discrete analyzers.

The foregoing data was extracted and adapted from SDi's Global Assessment Report, 9th Edition. For more information, contact Glenn Cudiamat, VP of Research Services, Strategic Directions International, Inc., 6242 Westchester Parkway, Suite 100, Los Angeles, CA 90045, (310) 641-4982, fax: (310) 641-8851, e-mail: cudiamat@strategic-directions.com