FIAlab Instruments  Leaders in Flow Injection Technology

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FIA/SIA Principles

The manual handling of solutions (known as "beaker chemistry") remains the Achilles Heel of modern analytical instrumentation.  It is currently being replaced by flow injection analysis (FIA), which is computer compatible and allows automated handling of sample and reagent solutions with a strict control of reaction conditions. FIA was first described in Denmark by Ruzicka and Hansen in 1975.  Since then the technique has grown into a discipline covered by six monographs and more than 15,000 research papers. The scope of the method grew from serial assay of samples to a tool for enhancement of performance of spectroscopic and electrochemical instruments.  Most recently FI became applied in biology for study of live cells by fluorescence microscopy and flow cytometry.  Other fields include monitoring of chemical processes in real time, biotechnology, immunoassays including antibody/antigen reactions.   The First Generation - Flow Injection  Analysis The Second Generation - Sequential Injection Analysis Additional Information Please visit our on-line list of research articles

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The First Generation - Flow Injection  (FI)

Flow Injection Analysis

Flow Injection Continuous Flow

Flow Injection Analysis (FIA), the first generation of FIA techniques, is also probably the most widely utilized. In its simplest form, the sample zone is injected into a flowing carrier stream of reagent. As the injected zone moves downstream, the sample solution disperses into the reagent, causing the product to form. A flow through detector placed downstream records the desired physical parameter such as colorimetric absorbance or fluorescence. The modern Flow Injection Analysis system usually consists of a high quality multichannel peristaltic pump, an injection valve, a coiled reactor, a detector such as a photometric flow cell, and an autosampler. Additional components may include a flow through heater to increase the speed of chemical reactions, columns for sample reduction, debubblers, and filters for particulate removal. The typical FIA flow rate is one milliliter per minute, typical sample volume consumption is 100 microliters per sample, and typical sampling frequency is two samples per minute. FIA assays usually result in sample concentration accuracies of a few percent.

FIA Lab-On-Valve The FIA Lab-On-Valve® integrates all connections, sample loop, and flow cell into one simple manifold.  No need to purchase separate expensive manifolds for each type of assay.     Please visit our Agricultural and Environmental Testing page for discussions of specific applications for FIA.

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The Second Generation - Sequential Injection and Bead Injection   

Sequential Injection Analysis Sequential Injection Analysis (SIA) is the second generation approach to FIA compatible assays. SIA usually consists of a single-channel high precision bi-directional pump, a holding coil, a multiposition valve, and a flow through detector. The system is initially filled with a carrier stream into which a zone of sample and a zone of reagent(s) are sequentially aspirated into a holding coil, forming a linear stack. These zones become overlapped due the parabolic profile induced by differences between flow velocities of adjacent streamlines. Flow reversals and flow acceleration further promote mixing. The multiposition valve is then switched to the detector position, and the flow direction is reversed, propelling the sample/reagent zones through the flowcell. The advantage of SIA over the more traditional flow injection analysis (FIA) is that SIA typically consumes less than one-tenth the reagent and produces far less waste – an important feature when dealing with expensive chemicals, hazardous reagents, or online/remote site applications. One disadvantage of SIA is that it tends to run slower than FIA.

SIA Lab-On-Valve® SIA in Lab-On-Valve® (LOV) format is a groundbreaking technology that has won an enthusiastic acceptance in the research community for its versatility, and in the routine laboratory for its reliability. The LOV integrates manifold components, including a fiber optic coupled flow through cell, into a single unit mounted on a multiposition valve. The SIA LOV is used as a platform for microSequential Injection as well as for Bead Injection and Sequential Injection Affinity Chromatography.  Please visit our Biomolecular Assays page for additional discussions on these applications. MPG Movie Clip demonstrates the ease at which microbeads are manipulated from holding port to optical flowcell, all within the LOV manifold.  (4 MB long, may take a minute or so to download). Online process monitoring using SIA is often an ideal solution. The low reagent/sample consumption, waste production, and nearly hands-off robustness make SIA the perfect choice. Example online applications include fermentation monitoring of ammonia, glycerol, and glucose.   Or automated sample dilutions prior to absorbance monitoring, perhaps many thousands fold.  Also remote site monitoring, where the system may run for days without user intervention.

Please email or phone FIAlab Instruments for additional product information. Email: fialab@flowinjection.com, Voice: 425-376-0450 or 1-800-963-1101,  Fax: 425-376-0451

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