Breakthrough Procedure

The adsorbent and adsorbate interaction obtained using the pulse test is at a diluted feed condition. So, the interaction information might not fully represent the actual interaction since the commercial feed concentration is normally much higher. To be more representative, the breakthrough technique is introduced. 

The breakthrough procedure is similar to the pulse test procedure except a large amount of high feed concentration is used. The breakthrough procedure can be described as follows  

1) Introduce solvent into a packed adsorbent column at a fixed flow rate, pressure and temperature. 

2) Introduce a feed mixture to be separated until the effluent reaches the feed composition. The feed breakthrough comprises the components to be separated, the tracer and the desorbent. 

3) Introduce solvent until no component in the feed mixture is detected in the effluents. 

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Although a proper cycling procedure has been used between alternate beds, an unexpected contamination of the adsorbent would cause a premature breakthrough of the beds resulting in the release of contaminants. A routine shutdown would normally only involve the shut off of the gas flow from the process. 

An important breakthrough in that respect was the use of soHd-phase organic synthesis (SPOS) where the attachment of the substrate to an insoluble support allowed for easy workup (filtration) and for rapid generation of products via split-mix procedures [1,2]. An important subsequent development consisted of the immobihzation of reagents, scavengers and catalysts. This technique, coined polymer-assisted solution phase chemistry (PASP), allowed solution phase synthesis of compoimds, yet still enjoying the bene-... 

An important breakthrough in HTS ee assays came from the group of Reetz in late 1990, with the introduction of mass spectroscopy (MS)-based procedures [90]. These methods use special asymmetrically isotope-labeled compounds. Enzymatic transformations of these compounds usually lead to two pseudoenantiomeric compounds whose relative concentration can be estimated using MS techniques. 

More particularly, a serious breakthrough was achieved in the methods of electrochemical calorimetty. Initial conclusions as to anomalous heat evolution during the electrolysis of solutions prepared with heavy water were caused by an incorrect formulation of control experiments in light water. In fact, none of the communications confirming anomalous heat evolution have been free of procedural errors, so that one cannot even discuss a sporadic observation of this effect. In contrast to all other experimental manifestations, heat evolution is indicative of any possible nuclear transformation, which implies that in its absence, neither reaction (33.4.1) nor reaction (33.4.2) can be suggested to occur. 

Sensitive analytic procedures enable detection and measurement of very low tracer levels. In tracer studies, an identifiable tracer material is injected through one or more injection wells into the reservoir being studied. Water or other fluid is then injected to push the tracer to one or more recovery wells in the reservoir. The output of the recovery wells is monitored to determine tracer breakthrough and flow through the recovery wells. Analysis of the breakthrough times and the flows yields important information regarding how to perform the secondary or enhanced recovery processes. 

When fortifying air tubes or air filters, the use of the formulated active ingredient in water is not recommended since the material on the air tube or filter must dry before air is drawn over the matrix. If the field fortification is nol dry on tiie sorbenf or air filter, breakthrough of the fortification solution may occur through the air filter or air tube into the back portion of the air tube and invalidate the procedure. 

An online filter was also used to protect the analytical column. A guard column was used before the T to prevent breakthrough. A restrictor was used to balance the pressure before, during, and after the valve switches. After sample transfer, the valve was switched back. With this method, both water-insoluble retinoids and water-soluble retinoic acid were extracted simultaneously. Because of the minimal light exposure of these light-sensitive analytes during the procedure, an extraction recovery of 97 to 100% was achieved with a quantitation range of 100 fmol to 3 nmol. 

The introduction of g.l.c. for oligosaccharide analysis constituted a major breakthrough in the field. In addition to strategies for accurate and sensitive quantitation of monosaccharide type (19,20), chiral procedures may be adopted for enantiomeric (d and l) determination (21). The sensitivity of h.p.a.e. chromatography with pulsed amperometric detection now provides an alternative to g.l.c. for oligosaccharide compositional analysis (22). 

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