Online monitoring methods

The existing IRAC website (http //www.irac-online.org) has now been on-line since 2001 and has become the main home for IRAC information. It has recently been completely redesigned and updated. Data available include the IRAC Monitoring Methods, the IRAC Mode of Action Qassification Scheme, Project and Coimtry Group updates, meeting minutes, member contact details and useful hnks, details of published articles and copies of new posters recently produced. 

R315 I. M. Clegg, C. M. Gordon, D. S. Smith, R. Alzaga and A. Codina, NMR Reaction Monitoring During the Development of an Active Pharmaceutical Ingredient , Anal. Methods, [online computer file], 2012, 4, 1498. 

Orton, C.R., Fraga, C.G., Christensen, R.N. et al. (2012). Proof of concept experiments of the multi-isotope process monitor An online, nondestructive, near-real-time monitor for spent nuclear fuel reprocessing facflities, Nucl. Instrum. Methods Phys. Res. A 672,38-45. 

Additionally, online monitoring methods have been developed to adapt off-line characterization methods into in situ (i.e., in-reactor) probes for determination of kinetics and monomer conversion with optical methods such as mass spectroscopy (MS), ESR, FTIR, near IR, and Raman spectroscopy. However, frequently, due to high turbidity and viscosity of the polymer reaction milieu, the optical surfaces are easily fouled, leading to frequent sensor failure. Furthermore, data acquired with these probes are model dependent the empirical and inferential calibration schemes used can be expensive and time consuming to develop and can drift and become unreliable as reactor conditions change and as sensors become fouled. Another limiting feature of these methods is that they usually measure only one characteristic of the reaction, such as monomer conversion and are not directly sensitive to polymer molecular mass and intrinsic viscosity. More detailed discussion of these techniques can be found in Chapters 6-10 of this book. 

Several online monitoring methods for polymerization have been reviewed [63, 64]. While some of these methods are still in development or suited for laboratory use, many monitoring techniques, in particular spectroscopic techniques, have found their way into industrial processes. There are several reaction features that could be addressed through improved online monitoring techniques in the production of water-soluble polymers. These techniques are used to... 

Available online or at-line monitoring methods of cultivations currently focus on the measurement of bulk parameters such as viable or total cell density, cell morphology, pH, (dissolved) gas concentrations, or a relatively small number of metabohtes using (FT-)IR or (FT-)Raman spectroscopy, which has been reviewed elsewhere [92-94]. Population-resolved monitoring currently involves the necessity to take samples and perform elaborate assays on them as described in Section 4.3.3.1, for example, involving online flow cytometry [95]. Since population heterogeneity influences the overall behavior during the cultivation. 

Inspection techniques for the detection and measurement of corrosion range from simple visual examination to nondestructive evaluation. Significant technological advances have been made in the last decade. For example, the combined use of acoustic emission (AE) and ultrasonics (UT) can, in principle, allow an entire structure to be inspected and growing defects to be quantified in terms of length and depth. Advanced corrosion monitoring methods have been developed that have both online capabihty and the abihty to detect problems at an early stage. The oil and gas production and petrochemical industries have assumed a... 

There are several methods to monitor the off-gas analysis. Online gas chromatography is commonly used. The daily operation for inlet and outlet gases is balanced to project growth in the bioprocess. High operating cost is the disadvantage of the online system. 

E. Zilkha, T.P. Obrenovitch, A. Koshy, H. Kusakabe, and H.P. Bennetto, Extracellular glutamate online monitoring using microdialysis coupled to enzyme-amperometric analysis. J. Neurosci. Methods. 60,1-9 (1995). 

Papadopouluo-Mourkidou E. et al., 2001. Use of an automated online SPE-HPLC method to monitor caffeine and selected aniline and phenol compounds in aquatic systems of Macedonia-Thrace, Greece. Frese-nius J Anal Chem 371 491. 

Automatization of all stages of the analytical process is a trend that can be discerned in the development of modern analytical methods for chemical manufacture, to various extents depending on reliability and cost-benefit considerations. Among the elements of reliability one counts conformity of the accuracy and precision of the method to the specifications of the manufacturing process, stability of the analytical system and closeness to real-time analysis. The latter is a requirement for feedback into automatic process-control systems. Since the investment in equipment for automatic online analysis may be high, this is frequently replaced by monitoring a property that is easy and inexpensive to measure and correlating that property with the analyte of interest. Such compromise is usually accompanied by a collection of samples that are sent to the analytical laboratory for determination, possibly at a lower cost. 

Many of the characterization techniques described in this chapter require ambient or vacuum conditions, which may or may not be translatable to operational conditions. In situ or in opemndo characterization avoids such issues and can provide insight and information under more realistic conditions. Such approaches are becoming more common in X-ray adsorption spectroscopy (XAS) methods ofXANES and EXAFS, in NMR and in transmission electron microscopy where environmental instruments and cells are becoming common. In situ MAS NMR has been used to characterize reaction intermediates, organic deposits, surface complexes and the nature of transition state and reaction pathways. The formation of alkoxy species on zeolites upon adsorption of olefins or alcohols have been observed by C in situ and ex situ NMR [253]. Sensitivity enhancement techniques play an important role in the progress of this area. In operando infrared and RAMAN is becoming more widely used. In situ RAMAN spectroscopy has been used to online monitor synthesis of zeolites in pressurized reactors [254]. Such techniques will become commonplace. 

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