FIAlab Instruments
Leaders
in Flow Injection Technology
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FIAlab Instruments |
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Lab-On-Valve and Sequential Injection |
| A six position selector valve
is
the heart of LAB-ON-VALVE system, where ports #1 to #6, are
interconnected by strategically designed microchannels and to a
multipurpose
flow cell, probed by optical fibers. The peripherals of the
LAB-ON-VALVE comprise a 24,000 step 500 microliter syringe, connected with
the valve by a holding coil, PC, fiber optic Spectrophotometer, light sources,
reagent reservoirs and sample changer. Each port in the LAB-ON-VALVE
is assigned a specific function: port # 5 is a flow through port
designed to accept samples manually, from an autosampler or from
a monitored sample stream, with the aid of an auxiliary peristaltic
pump. Note that this pump is used only to bring sample solution to port
#5. Precise sample solution metering is carried out by means
of the flow reversal of the syringe pump when
the selector valve is turned to port #5. Similarly reagents are aspirated
from ports # 3, #4 and #6, while the composite sample zone is transported
from the holding coil through port #2 into the flow cell by the forward
movement of the syringe pump. Port #1 of the leads to waste, while
the remaining ports serve as reagent sources. The central port
can be connected either to a single syringe pump ( as shown) or to two
syringe pumps. A two pump system affords a wider range of flow rates (
by using 500 microliter and 100 microliter syringe) and more flexibility
for multiple reagent based experimental protocols. (Instrument).
The multipurpose flow connected to port #2 , can be configured to measure UV-VIS absorbance spectra, fluorescence or chemiluminiscence. The photograph shows flow cell in absorbance configuration, where optical fibers, encased in stainless steel are facing each other through a 5 mm long optical path while the cell is shown filled with a blue dye. This light path can be adjusted down up to 0.5 mm when monitoring highly colored solutions, by repositioning the tips of the optical fibers. ( see the drawing ). For fluorescence measurement the fibers are repositioned at right angles ( as shown ) while the flow is directed to waste by side flow channel. Simultaneous absorbance and fluorescence measurement is based on the use of three fibers and dual channel solid state spectrophotometer.(Instrument) Since Sequential Injection is based on combination of physical
and chemical processes that must be repeated throughout every measurement
cycle, it is imperative that the physical processes such as injection,
mixing and optical monitoring are perfectly reproducible. This feature
of LAB-ON-VALVE is shown tested by repeatedly injecting 20
microliters of dye samples ( ten injections ) of three different concentrations,
into a colorless carrier stream and by monitoring absorbance through 1mm
path length at 520nm.
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| 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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