Process optical flow-through cell

Analytical interfaces are integrated into the AuMpRes set-up for at-line analysis by sampling and subsequent chromatography (HPLC) [108], Moreover, this allows online analysis by infrared or Raman spectroscopy. Real-time monitoring of the chemical processes can be achieved via spectroscopic measurements, for which suitable optical flow-through cells have to be installed at selected positions of the micro reaction system. 

Figure 7.4 Collection of commercial Raman probes designed for different installations (a) laboratory scale probe with interchangeable immersion or noncontact optics, shown with immersion option (b) probe shown in (a) installed in laboratory fermentation reactor (c) production scale immersion probe (d) probe shown in (c) installed in a glass reactor (e) gas phase probe with flow through cell (f) probe shown in (e) installed in process piping (g) wide area illumination (WAI) noncontact probe after completion of a pharmaceutical tablet coating operation. Adapted, with permission. Copyright 2004 Kaiser Optical Systems, Inc.

At-line sampling may involve a flow-through cell in the NIR spectrometer in one process a glass-lined steel reaction vessel was used in combination with a fibre optic probe for measurements in a full scale chemical plant reactor [57]. Fibre optic bundles can be used to transmit NIR radiation to the reaction matrix and take signal back to the spectrometer. NIR is notoriously sensitive to changes in temperature and methods for keeping the temperature constant must be incorporated into the instrumentation. 

FTIR instrumentation is mature. A typical routine mid-IR spectrometer has KBr optics, best resolution of around 1cm-1, and a room temperature DTGS detector. Noise levels below 0.1 % T peak-to-peak can be achieved in a few seconds. The sample compartment will accommodate a variety of sampling accessories such as those for ATR (attenuated total reflection) and diffuse reflection. At present, IR spectra can be obtained with fast and very fast FTIR interferometers with microscopes, in reflection and microreflection, in diffusion, at very low or very high temperatures, in dilute solutions, etc. Hyphenated IR techniques such as PyFTIR, TG-FTIR, GC-FTIR, HPLC-FTIR and SEC-FTIR (Chapter 7) can simplify many problems and streamline the selection process by doing multiple analyses with one sampling. Solvent absorbance limits flow-through IR spectroscopy cells so as to make them impractical for polymer analysis. Advanced FTIR... 

FIGURE 51 Scheme of the flow-through channel-resolved immunosensing system for the determination of AFP and CEA (a) flow cell (b) flow-through CL immunosens-ing system and process of immunoassay (c) transect of flow cell for immunoassay and (d) optical shutter. WB wash buffer RB regeneration buffer CS CL substrate S mixture of sample and tracer antibody M I anti-AFP immobilized membrane M II anti-CEA immobilized membrane. (Adapted from Fu, Z. et al. 2008. Biosens. Bioelectron. 23 1063-1069. With permission.)... 

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