Flow cell development using functionalized

The combination of these two powerful characterisation techniques can provide the ability simultaneously to characterise the molecular distribution and to identify and quantify IR-active functional groups in the distribution. The main problem in linking such technologies is the choice of solvent or eluent used to carry the polymer through the SEC system. Many of the typical SEC solvents have strong absorption bands in wide regions of the infrared spectrum. Developments have centred around the use of low-volume cylindrical internal-reflection flow cells for use in the FTIR system. However, their use is still restricted in many cases to IR-friendly SEC solvents. 

EC-ALE studies of ZnTe using a TLEC were performed with up to 20 cycles of deposition [130], Coulometry was the only analysis performed on the deposits. A plot of coverage as a function of the number of cycles was linear, as expected for a surface limited process. No thicker films have as yet been formed using the flow deposition system. At present there is no reason to believe that the cycle developed for 20 cycle deposits will not produce good quality deposits of any given thickness, using the automated flow-cell system. 

Dual working electrode systems have been developed which can be operated with the electrodes in parallel or in series. In the later one working electrode is located upstream of the other and is complementary in function. This system can be used with analytes which undergo reversible oxidation or reduction and in use enhances selectivity. In the former configuration the electrodes are mounted at 90° to one another in the flow-cell. Different fixed voltages can be applied to the electrodes and the response monitored and ratioed to check peak purity. Alternatively, one electrode can be operated as a cathode the other as an anode and oxidants and reductants determined simultaneously. 

To this end multiphysics simulations have been successfully employed to model and calculate hydrodynamic flow and the associated shear forces, transport phenomena due to diffusion and convection, the effects of Joule heating, as well as electrically induced forces acting on cells for the purpose of organ assembly and the resulting cell trajectories. Using this approach, microsystems may be evaluated with respect to the desired function even before building devices, enabling efficient optimization and acceleration of development [5]. 

The choice for the type of LC-FTIR coupling (flow cell or solvent-elimination) depends on the particular application of the user, where aspects such as type of spectral information needed, required sensitivity, and ease of use are main criteria. Flow-cell LC-FTIR is relatively simple and straightforward, and has developed into a special-purpose technique that can be used in a routine fashion for the monitoring of major mixture constituents with specific functional groups. Solvent-elimination LC-FTIR is somewhat more complicated requiring (sometimes complex) evaporation interfaces, but allows characterization of minor sample components with a high level of confidence. At present, the practical application of FTIR detection in LC is still quite limited. 

Recently, a streptavidin-functionalized capillary immune microreactor (Figure 10.8) was developed for highly efficient chemiluminescent immunoassay [67]. The functionalized capillary was used as both a support for highly efficient immobilization of antibody and a flow cell for flow-through immunoassay. For the immunoassay protocol,... 

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