In-line analysis

Spectrophotometric methods for determining concentration of Pu(111, IV, VI, and "polymer") in nitrate media have been reported.(30) Adaptation of such procedures to routine rapid in-line analysis of feed and raffinate solutions may be possible. 

It is worth briefly pointing out the difference between in-line and online analysis. In-line analysis does not involve removal of the sample from the reaction vessel, for example in determining water or oxygen content. On-line analysis does involve removing a sample, usually as a side stream, which adds to the complexity of the plant since the sample off-take equipment will often need to be built to the same integrity as the plant. There are four common techniques employed ... 

In some cases the object under study has to be continuously monitored. Then on-line analytical methods are applied by which the system can be directly measured. The analytical process then runs without sampling and sample preparation, as can be seen in Fig. 2.3a. The analytical process is shortened even more in the case of in-line analysis where measurement and... 

Fig. 2.3. The analytical process in case of on-line analysis (a) and in-line analysis (b)... 

In-line analysis and continuous monitoring. In this style of analysis there is no possibility of repeating the measurement, so the concept of IQC as used in the guidelines is inapplicable. 

This non-destructive technique is a very suitable tool for rapid in-line analysis of inorganic additives in food products (Price and Major, 1990 Anon, 1995). It can be readily used by non-skilled operators, and dry materials can be pressed into a pellet or simply poured into a sample cup. The principles of this technique related to food analysis are described by Pomeranz and Meloan (1994). A useful Internet site is http //www.xraysite.com, which includes information about different XRF instruments from various companies. Wavelength dispersive X-ray fluorescence (WD-XRF) or bench-top energy dispersive (ED-XRF) instruments are available. XRF is a comparative technique, thus a calibration curve needs to be established using food products of the same type as those to be... 

Some analyzers do not use a sampling system the analyzer probe is put directly into the process line. Many spectroscopic analyzers can be operated with a probe directly interfaced with the process (called in-line analysis). Some concerns with taking this approach are calibration, and how to introduce a real standard to the system for instrument verification. These are questions one must be asking. 

The Lasentec particle/droplet size analyzer can be used for laboratory and in-line analysis in the +1 pm size range over a wide range of operating conditions. 

Papers by DeMaesserchalck et al. and Bemtsson et al.f" are significant in that they disucss the mathematical treatments involved in following blend uniformity and in-line analysis of active. 

Special features/comments complete high-throughput organic chemistry stand with synthesizer, SPE, balance, vortexer, liquid-liquid extraction module, vacuum centrifuge cooling with cold nitrogen gas multichannel (up to 8) pipette for solvent delivery reactive gas chemistry possible (rv can be pressurized up to 6 bar) 16 independent heating zones analytical port for in-line analysis (optional) on-board liquid-liquid extraction... 

In-line analysis and control systems that prevent the rerunning of a nonspecification product are safer and certainly better way to run a complex operation. While samples are still taken and analyzed in the laboratory, the research is mostly used for calibration purposes and to check online analysis. 

The Raman technique has been readily adapted for on-line process analysis, especially in the pharmaceutical industry ". It has the benefits of mid IR, e.g. the ability to identify compounds from the vibrational fundamentals, without the constraints of mid IR, e.g. the limitations of the optical materials that can be used. Its popularity is also due in part to the excellent throughput of optical fibres for the radiation required for Raman, i.e. in the Vis and NIR regions. This use of optical fibre probes (Figure 9.14) facilitates easy in-line analysis because the sample can be remote from the instrumentation, even to hundreds of metres in distance. Fibre optic multiplexers are also available, allowing many samples to be analysed sequentially. Small laser diode sources and CCD detectors can be attached to the optical fibres and changed as required, rendering the overall device small and flexible. Radiation from the laser diode light source is transmitted to the sample by optical fibre... 

An area that will require attention in the future involves in-line analysis of polymer blends during processing potentially allowing feedback information to improve uniformity of the resultant blend. In-line morphology determination, rheological measurements, and shear-induced phase behavior are subjects for consideration. Rheo-optical studies under shear for low molecular weight PS/PIB blends near phase separation conditions were... 

In addition to on-line and in-line analysis, very often off-line systems are used in industry. Intermediates and products are analysed with laboratory analyzers. An example of this is the equipment constructed for the content uniformity analysis and dissolution rate determination of pharmaceutical tablets.The tablet is dissolved under well-defined conditions and the solution analysed using a flow technique with voltammetric detector (Fig. 11). 

Each spectrum in the in-line prediction was measured for 2 minutes. The real-time prediction for the quantitative in-line analysis for real industrial... 

Since microreactor technology was first seen as an effective method for the synthesis of chemical compounds, enormous advances have been made in this area. The examples discussed in this chapter and many other illustrations in the Hterature, prove the potential of flow chemistry in chemical and phamiaceutical production and confirm the expected benefits and the intensification of chemical processes. The above-mentioned flow processes furthermore illustrate the flexibiHty of microfluidic devices, as flow chemistry allows the Hnking of individual reactions into multi-step reactions as well as preparing a series of analogues by simple modifications. A variety of technical approaches can additionally be considered for the implementation of flow processes, such as the automated and real-time in-line analysis and... 

Nielsen et al. described an automated system for the characterization of liquid-phase ethylene polymerizations [10]. The system had control of residence times, concentration of catalysts, temperature and pressure. In real time with in-line sensors, it was possible to determine the heat evolved from the reaction and to determine catalyst performance. Thus, by using a carefully controlled microscale reactor with in-line analysis capabilities, a complex polymerization reaction could be characterized in the laboratory setting. 

The surface mount hard vare, which can be valves, flow controllers, filters, gauges and analyzers, which now constitutes a long list of components, has the fluid fed from below. Three major vendors provide different flow path systems but all surface mount components are interchangeable. Many analyzers that are often used for in-line analysis can also be mounted in the flow path of the NeSSI-based hardware. 

Of course, there are many possibilities for integrating spectroscopic cells into a microreaction system. Because of the small cross-sections within the microfluidic devices, typically no bypass is necessary for such adaptation. Spectroscopic process monitoring can be either realized subsequent to the microreactor setup or direcfly within the microreactor. As an example. Figure 6.1 shows a pragmatic and flexible setup that allows spectroscopic in-line analysis of microreaction processes. This setup was designed for monitoring parameter screenings and allows adaptation of one or more of the above-mentioned spectroscopic methods. Miniaturized optical... 

Although the described spectroscopic methods for quantitative in-line analysis can in principle be applied to all kinds of screening experiments that comprise systematic variations of process parameters, this approach has to be handled with care since some of the parameters have an undesired non-linear effect on a spectrum. For instance, in NIR spectroscopy, an increase in temperature can cause band shifts and influence the peak height. Variations in stoichiometry, which can be easily achieved in a microreaction process by changing the reactant flows, have a direct impact on the analyzed compound concentration. However, such modifications can be calculated subsequent to the reaction, if concentrations are in the linear detection range or the detection range was calibrated in advance. 

G. Billeb, M, Schwarzer, S, Loebbecke, In-line analysis in microreaction technology suitable tools for process screening and optimization, Chem. Eng. Technol. 2007, 30, 370-378,... 

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