product review
Flow Injection Analysis: Quietly Pushing Ahead The field and the applications are growing, even if the technique still seems to be overlooked by some laboratory chemists. James P. Smith and Vicki Hinson-Smith xperts on flow injection analysis (FIA) agree on one thing: The technique is surprisingly under-used by laboratory chemists. Perhaps this is because automation was too expensive or took too long when FIA was introduced in the mid-1970s. But FIA enthusiasts say the game has changed since then. “This is a technique that allows chemists to easily automate and optimize well-developed wet chemical methods for routine laboratory use,” says Gary Christian of the University of Washington and previously with Alitea U.S.A., now called Global FIA, Inc. “You can even program an analyzer to switch from one analyte to another during the analysis of a batch of samples. . . . But FIA has never been a popular product of larger instrument companies, so smaller firms produce most of these analyzers.” FIA is at least fulfilling its potential in the sense that a wealth of literature describing a wide range of applications has been published. For example, FIA offers several advantages over the manual handling of solutions: It is computer-compatible, allows automated handling of solutions, and provides strict control of reaction conditions. Because sample handling is so versatile, FIA can serve as a front end to practically all spectroscopic and electrochemical detectors and to various clinical, environmental, and industrial assays. Biologists have used FIA in fluorescence microscopy for receptor
BROO SORENSEN C/O JAROMIR RUZICKA
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and live cell studies and ultrafast drug screening and in flow cytometry for automated sample introduction and studies of fast cell–reagent kinetics. Other applications include real-time monitoring of chemical processes, automated renewal of the sensing layer in chemical transducers, and electrochemical methods, such as hydrodynamic voltammetry and ion-selective electrode measurements.
Advances in computerization, microfluidics, and hardware have facilitated the further development of new flow injection techniques. Especially noteworthy are the development of new on-line UV-digestion techniques, advanced online distillation techniques, and combined FIA–sequential injection analysis (SIA) techniques; the incorporation of ion-selective electrodes; and improve-
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product review
Table 1. Selected commercial flow analyzers1. Product
ASI/Eppendorf Variable Analyzers FIAlab-3500
FIAstar 5000
FloPro 4P, FloPro 9P
Company
AMKO Systems, Inc. 250 W. Beaver Creek Rd. Unit 6 Richmond Hill, Ontario Canada L4B 1C7 (905) 771-1444
FIAlab Instruments, Inc. 14400 Bel-Red Rd. Ste. 108 Bellevue, WA 98007-3926 (800) 963-1101
Foss North America 7682 Executive Dr. Eden Prairie, MN 55344 (952) 974-9892
Global FIA, Inc. P.O. Box 480 Sixth St. Fox Island, WA 98333 (253) 549-2223
URL
www.amkosystems.com
www.flowinjection.com
www.foss.dk
www.globalfia.com
Price
$10,000–$20,000
~$15,000
~$15,000–$45,000
~$10,000–$30,000
Applications
Chemical, environmental, biotech- Sample handling for FTIR, induc- Hundreds of methods—most comnology, pharmaceutical, and food tively coupled plasma MS, chemi- monly, environmental, nutrients, and beverage cal sensors, immunoassays; and industrial process water-quality or environmental analysis; proteomics
Hundreds of organic and inorganic analytes for on-line process, lab, and field analysis; industrial proprietary sample streams
Pumps and flow rates
Variable-speed, multichannel peristaltic pumps with various tubing sizes; flow rates typically 3–10 mL/min
Two 4-channel peristaltic pumps with variable speed and stand-by feature; 0.42–5.74 mL/min
Global FIA milliGAT, Cavro syringe, and Cavro peristaltic pumps; 6 nL/min–6 mL/min
Manifold and flow diameter
2–3 min for a typical analysis
0.7-mm flow diam
FIA, SIA, and zone fluidics; 0.80-mm flow diam
Sample throughput
60–120 samples/h
1–3 min/sample
Sample injection
120-position, random-access autosampler with separate rack for calibration and check standards
Gilson autosamplers
Typically 20 samples/h with 2- to Number of 100-µL samples samples and sample volume
20- to 400-µL sample volume
Variable sample number and volume
1–400 µL/s
Detectors
Include colorimeters, ISEs, conductivity sensors; external detector signals accepted if adaptor modules are used
Spectrometer-based absorbance; photomultiplier tube-based fluorescence; chemical; bioluminescence
Digital dual-wavelength photome- UV–vis absorbance, chemilumiter with automatic interchangeable nescence with liquid-core waveinterference filters guide cell, amperometric
Accessories
Selector and injection valves, peri- Heaters, autosamplers, additional staltic pump, mixing/reaction man- pumps and valves ifold, and master controller module with detector usually included; autosampler and printer available
All tubing, injection loops and coils, and gas diffusion membranes; prepacked cadmium reductor columns; pump tubes are pre-cut; reagent and waste bottles
Components and supplies; sampleconditioning systems, including membrane sampling devices and self-cleaning sample-filtering system
Special features
Flexible systems allow user to LOV manifold designed to miniachange processes or analytical turize FIA, SIA, and BIA sequences easily; systems can be fitted with various interchangeable detectors
Up to 3 channels; start up in
