In situ on-line

Recent advances and further improvements have led to a broad variety of applications for single-mode microwave instruments, offering flow-through systems as well as special features such as solid-phase peptide synthesis or in situ on-line analy-... 

Spoilage of the reference electrolyte is one of the major problems during long-term cultivations. Monzambe et al. [292] and Buhler (personal communication) have reported discrepancies of one pH unit between in situ on-line and off-line measurements which were caused by black clogging of the porous diaphragm. Either acidification or pressurization of the electrolyte was suitable to restrain this. 

Clausen BS, Schiotz J, Grabek L, et al. Wetting/non-wetting phenomena during catalysis evidence from in situ on-line EXAFS studies of Cu-based catalysts. Top Catal. 1994 1 367. 

Gerhardt A., Ingram M.K., Kang I.J. and Ulitzur S., 2006. In situ on-line toxicity biomonitoring in water recent developments, Environ Toxicol Chem 25 2263-71. 

It is mainly in absorption spectrometry that the concepts of on-line remote control by optical fibers have been defined [172]. As a starting hypothesis, they all use the in situ on-line measurement over long periods and they can be summarized as follows ... 

Topsoe N-Y (1994) Mechanism of the Selective Catalytic Reduction of Nitric Oxide by Ammonia Elucidated by in Situ On-Line Fourier Transform Infrared Spectroscopy. Science 265 (5176) 1217-1219... 

For optimizing the use of biocides against biofilms, it will be useful to monitor their development on surfaces in situ, on line, in real time and possibly in a way which can be automated. Some devices have been developed which fulfil these requirements (Flemming, 2003 Tamachkiarow and Flemming, 2003). 

A wide variety of particle size measurement methods have evolved to meet the almost endless variabiUty of iadustrial needs. For iastance, distinct technologies are requited if in situ analysis is requited, as opposed to sampling and performing the measurement at a later time and/or in a different location. In certain cases, it is necessary to perform the measurement in real time, such as in an on-line appHcation when size information is used for process control (qv), and in other cases, analysis following the completion of the finished product is satisfactory. Some methods rapidly count and measure particles individually other methods measure numerous particles simultaneously. Some methods have been developed or adapted to measure the size distribution of dry or airborne particles, or particles dispersed inhquids. 

The on-line principle has also been extended into the field of detection (Fig. 8). Thus, it is now possible to record FTIR [27-31] and Raman spectra in situ [32, 33], and there have been considerable advances in the on-line coupling of thin-layer chromatography with mass spectrometry. Here it has been, above all, the research groups of Wilson [34-36] and Busch [37-40] that have made the necessary instrumental and methodological advances, so that TLC must no longer be viewed as merely a clean-up method. Rather it forms the essential central point for all these on-line coupling techniques. 

There are a number of well-established systems for the aseptic packaging of liquids. Notable among these are those packs constructed, box form, in situ on the filling line from a cardboard, aluminium, plastic laminate sheet, such as TetraPak or Combi-box. In the TetraPak system, the packing material enters the filling machine from a feed roll the sheet contact surface is sterilised with warm hydrogen peroxide solution it is formed into a tube, and its lower end is heat-sealed across the width the tube is filled, sealed at the upper end, cut and then folded into a box shape. This produces a continuous output of filled cartons with premium utilisation of bulk storage capacity. 

Chemical separations are achieved using chromatographic and, to a much lesser extent, electrophoretic methods. In chromatographic methods, separation is based on variation in the distribution of different compounds between two dissimilar phases—a stationary phase and a mobile phase. Further differentiation can be made between chromatographic procedures in which the individual components elute from the stationary phase and are monitored on line (column chromatography) and procedures in which the components are measured in situ on the chromatographic stationary phase [e.g., thin-layer... 

The versatility of Raman spectroscopy for the on-line analysis of polymers both in the laboratory and also in-situ on the production line is demonstrated and the benefits and disadvantages of the technique as an on-line method are considered. Application of the technique to an analysis of acrylic terpolymers, monitoring of polymerisation and on-line measurement of morphology/composition is... 

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