Returned eluate

A forward displacement is given to column 1 at 25 gal/min, using one half bed volume of returned eluate , and passing it back to the returned eluate tank. This allows the column to contain some chloride... 

The first half elution is carried out with 6 5 bed volumes of returned eluate at 20 gal/min and the liquor passed to the precipitation stages. 

In the second half elution, six bed volumes of fresh eluting solution are used, at 25 gal/min. This is passed to the return tank to become returned eluate for use in the next cycle. 

This assay is based on the separation and quantitation of bilirubin. The column was a C18 Novapak radial compression column. Solvent A contained 49% 0.1 M monobasic ammonium phosphate, 40% methanol, 10% acetonitrile, and 1% DMSO, adjusted with H3PO4 to pH 3.6. Solvent B contained 79% methanol, 20% acetonitrile, and 1% DMSO. The 16-minute run included a linear gradient from 50 to 100% solvent B in 3 minutes, maintaining 100% B for 13 minutes, followed by a return to starting conditions. The eluate was monitored at 450 nm, and detector response was linear with 0 to 500 pmol of bilirubin. 

Transfer tlie resin to a Ijeaker and add 10 ml of WAC resin (H form). Mix th e resins and return the mixture to the column. Run deionized water through the column at alxjul 1 BV /2 minutes until the eluate has a low conductivity, e.g. 50 micromhos. 

Contrary to conventional practice, it is not necessary to wait tmtil the steady response of the detector indicates that the eluate concentration is the same as the concentration in the stream of mobile phase pumped into the column to return to a pure mobile phase stream. In fact, a wide rectangular injection is usually sufficient, provided that a concentration plateau is eluted at the column exit. Admittedly, in such an implementation of the method, it becomes difficult to decide whether it is FACP or ECP (see next section) but this is irrelevant. If the width of the rectangular pulse is kept reasonably narrow, the amount of sample needed is comparable to that required in ECP for the determination of the isotherm in the same concentration range. 

Figure 8.8 Asahi moving packed bed. A, adsorption section B, elution section C, fluidized resin backwash D, resin collection hoppers with screen top and non-return valve outlet for resin E, transfer and backwash water overflow F, feed G, barren effluent H, eluant I, eluate product J, backwash supply K, resin flow [1]. Copyright 1987 John WUey Sons, Inc. This material is used by permission of John Wiley Sons, Inc.

Precipitation of uranium from duate. In the Dawn mill, uranium was recovered from eluate by two-stage precipitation with alkali. In the first stage, pH is increased to 3.3 to 3.6 by addition of CaO slurry. This precipitates most of the ferric iron that may have been adsorbed with the uranium and removes most of the sulfate as CaS04. Because the filter cake contains 1 to 2 percent uranium, it is returned to the leaching circuit. 

Extract the sorbed anions with 20 ml diethyl ether saturated with HCl. Return this eluate to the column and wash through with ether-HCl. 

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