The advantages of LOV:
1) Transparency of flow and optical path
2) Versatility of flow cell design
3) Sample introduction by flow trough port
4) Miniaturization – compact and robust structure
The LOV concept achieves down-scaling of the SI system through integration of the sampling conduit and of the flow cell into a micro-machined compact structure mounted atop a conventional multi-position valve. The LOV modules are machined with a very high degree of precision and narrow tolerances. The LOV system operates in the microliter domain and is compatible with:
In contrast to other microfluidic devices, the volume of the sample path within the LOV is minimized by reducing the channel length, while channel diameter is kept wide(0.8mm ID), in order to prevent system clogging by matrix material often present in "real life" samples. The LOV module in Perspex (to the right) is configured for UV-VIS Spectrophotometry.
In this configuration the optical fibers are mounted axially in the flow through cell, using an Ocean Optics spectrophotometer as detector and a Tungsten, LED or Deuterium light source. The length of the light path within the LOV module can be selected from 1 to 10 mm. By using the cell extension module the light path can be further increased to 5, 10, 25 and 50cm.The picture to the right shows the LOV with light path extended to 25cm. For further details consult the complimentary CD Tutorial.
For this application the optical fibers are configured at right angles. A suitable combination of excitation sources (LED, Tungsten), and detectors (High Sensitivity Ocean Optics spectrophotometer or FIAlab's PMT ) is user selected. Since the flow cell can accommodate an additional optical fiber in the axial direction towards the illuminating fiber, fluorescence and absorbance can be monitored simultaneously. The picture to the right shows the LOV module configured for fluorescence monitoring. For further details consult the Fluorescence Flow Cell page or the complimentary CD Tutorial.
For this application the optical fibers are configured at right angles in order to maximize the volume of the flow cell monitored by optical fibers. Both fibers are connected to the photomultiplier.The picture shows the LOV module configured for chemiluminescence.
Voltammetry and Conductimetry
The LOV flow cell can accommodate up to three electrodes,making it suitable for voltammetry or potentiometry with two miniaturized ISE and one reference electrode. The picture shows the LOV module configured for voltammetry. For details consult the complimentary CD Tutorial.
Bead Injection Spectroscopy and microAffinity Chromatography
Bead Injection (BI), is the third generation of FIA techniques. In its simplest form, microspheres are injected into a conduit, where they are trapped at a selected location. Next, sample zone is injected and perfused through the beads, while sample components react with functional groups on bead surfaces. Retained analyte molecules are detected in their native form by spectroscopy, or reacted in situ with suitable color or fluorescent reagents. Analyte molecules may also be eluted for detection. The picture shows the LOV module configured micro Chromatography. Example of such application is microAffinity Chromatography. For further details consult FIAlab SIChrom or the complimentary CD Tutorial.
Specifications and Material Compatibility
The LOV manifold is compatible with the FIAlab MicroSIA, FIAlab-3200 and FIAlab-3500 systems. The Lab on- valve module is offered in Plexiglas ULTEM or PEEK material, and with six or eight ports. Custom designs and materials are available upon request. Plexiglass is suitable for most applications, unless the processed solution does not contain organic solvents or more than 10% ethanol or methanol. The picture shows an 8 port LOV fabricated from Ultem.