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Rates, free-solution separations

The sohd can be contacted with the solvent in a number of different ways but traditionally that part of the solvent retained by the sohd is referred to as the underflow or holdup, whereas the sohd-free solute-laden solvent separated from the sohd after extraction is called the overflow. The holdup of bound hquor plays a vital role in the estimation of separation performance. In practice both static and dynamic holdup are measured in a process study, other parameters of importance being the relationship of holdup to drainage time and percolation rate. The results of such studies permit conclusions to be drawn about the feasibihty of extraction by percolation, the holdup of different bed heights of material prepared for extraction, and the relationship between solute content of the hquor and holdup. If the percolation rate is very low (in the case of oilseeds a minimum percolation rate of 3 x 10 m/s is normally required), extraction by immersion may be more effective. Percolation rate measurements and the methods of utilizing the data have been reported (8,9) these indicate that the effect of solute concentration on holdup plays an important part in determining the solute concentration in the hquor leaving the extractor. [Pg.88]

The importance of the withdrawal rate of solution waste fliom the gas-expansion separator was stressed in Sec. 5.42. Forced withdrawal using a pump is strongly recommended in preference over free outflow of reaction waste for ensuring optimum precision and long term trouble-free operation. This aspect should not be overlooked, at least in the design of a FI hydride generation system using gas-expansion separators. When gas-diffiision separators are used, the requirements may be different. [Pg.150]

It is the relative ease of hydrolysis of hemiacetals I and II from a polysaccharide that is so attractive in effecting dispersibility. Glyoxal-treated xanthan gum and other gums are very dispersible because of their relative insolubility but as the acetals are hydrolyzed, the gums begin to hydrate at a rate that allows each gum particle to remain separated to form lump-free solutions. [Pg.34]

Figure 9 Comparison of RP-LC (A) and CZE (B) separations of tryptic peptides of hGH. Peak assignments and correlations for selected fragments are noted. CZE background electrolyte 0.01 mol I Tricine, 0.045 mol I morpholine, 0.02 mol I NaCI, pH 8.0, detection at 200 nm, 316 V cm, 20 pA. LC column Aquapore RP-300 (4.6 x 250 mm), flow rate 1 ml min, detection 214 nm. Solvents A, 0.1% trifluoroacetic acid (TEA) in water B, 0.1% in acetonitrile gradient 0-20% B in 20 min, 20-25%B in 25 min. (Reprinted with permission from Grossman PD, Colburn JC, Lauer HH, et al. (1989) Application of free-solution capillary electrophoresis to the analytical scale separation of proteins and peptides. Analytical Chemistry 61(11) 1186-1194 American Chemical Society.)... Figure 9 Comparison of RP-LC (A) and CZE (B) separations of tryptic peptides of hGH. Peak assignments and correlations for selected fragments are noted. CZE background electrolyte 0.01 mol I Tricine, 0.045 mol I morpholine, 0.02 mol I NaCI, pH 8.0, detection at 200 nm, 316 V cm, 20 pA. LC column Aquapore RP-300 (4.6 x 250 mm), flow rate 1 ml min, detection 214 nm. Solvents A, 0.1% trifluoroacetic acid (TEA) in water B, 0.1% in acetonitrile gradient 0-20% B in 20 min, 20-25%B in 25 min. (Reprinted with permission from Grossman PD, Colburn JC, Lauer HH, et al. (1989) Application of free-solution capillary electrophoresis to the analytical scale separation of proteins and peptides. Analytical Chemistry 61(11) 1186-1194 American Chemical Society.)...
In a 500 ml. bolt-head flask, provided with a mechanical stirrer, place 70 ml. of oleum (20 per cent. SO3) and heat it in an oil bath to 70°. By means of a separatory funnel, supported so that the stem is just above the surface of the acid, introduce 41 g. (34 ml.) of nitrobenzene slowly and at such a rate that the temperature of the well-stirred mixture does not rise above 100-105°. When all the nitrobenzene has been introduced, continue the heating at 110-115° for 30 minutes. Remove a test portion and add it to the excess of water. If the odour of nitrobenzene is still apparent, add a further 10 ml. of fuming sulphuric acid, and heat at 110-115° for 15 minutes the reaction mixture should then be free from nitrobenzene. Allow the mixture to cool and pour it with good mechanical stirring on to 200 g. of finely-crushed ice contained in a beaker. AU the nitrobenzenesulphonic acid passes into solution if a little sulphone is present, remove this by filtration. Stir the solution mechanically and add 70 g. of sodium chloride in small portions the sodium salt of m-nitro-benzenesulphonic acid separates as a pasty mass. Continue the stirring for about 30 minutes, allow to stand overnight, filter and press the cake well. The latter will retain sufficient acid to render unnecessary the addition of acid in the subsequent reduction with iron. Spread upon filter paper to dry partially. [Pg.589]

C. Isolation and purification of XK-62-2 100 g of the white powder obtained in the above step B are placed to form a thin, uniform layer on the upper part of a 5 cm0X 150 cm column packed with about 3 kg of silica gel advancely suspended in a solvent of chloroform, isopropanol and 17% aqueous ammonia (2 1 1 by volume). Thereafter, elution is carried out with the same solvent at a flow rate of about 250 ml/hour. The eluate is separated in 100 ml portions. The active fraction is subjected to paper chromatography to examine the components eluted. XK-62-2 is eluted in fraction Nos. 53-75 and gentamicin Cja is eluted in fraction Nos. 85-120. The fraction Nos. 53-75 are combined and concentrated under reduced pressure to sufficiently remove the solvent. The concentrate Is then dissolved in a small amount of water. After freeze-drying the solution, about 38 g of a purified preparate of XK-62-2 (free base) is obtained. The preparate has an activity of 950 units/mg. Likewise, fraction Nos. 85-120 are combined and concentrated under reduced pressure to sufficiently remove the solvent. The concentrate is then dissolved in a small amount of water. After freeze-drying the solution, about 50 g of a purified preparate of gentamicin Cja (free base) is obtained. [Pg.1024]

The total consumption type of burner consists of three concentric tubes as shown in Fig. 21.5. The sample solution is carried by a fine capillary tube A directly into the flame. The fuel gas and the oxidant gas are carried along separate tubes so that they only mix at the tip of the burner. Since all the liquid sample which is aspirated by the capillary tube reaches the flame, it would appear that this type of burner should be more efficient that the pre-mix type of burner. However, the total consumption burner gives a flame of relatively short path length, and hence such burners are predominantly used for flame emission studies. This type of burner has the advantages that (1) it is simple to manufacture, (2) it allows a totally representative sample to reach the flame, and (3) it is free from explosion hazards arising from unbumt gas mixtures. Its disadvantages are that (1) the aspiration rate varies with different solvents, and (2) there is a tendency for incrustations to form at the tip of the burner which can lead to variations in the signal recorded. [Pg.786]


See other pages where Rates, free-solution separations is mentioned: [Pg.66]    [Pg.2814]    [Pg.31]    [Pg.260]    [Pg.242]    [Pg.19]    [Pg.332]    [Pg.117]    [Pg.93]    [Pg.2768]    [Pg.445]    [Pg.778]    [Pg.48]    [Pg.669]    [Pg.6]    [Pg.2814]    [Pg.1400]    [Pg.10]    [Pg.139]    [Pg.6051]    [Pg.123]    [Pg.706]    [Pg.416]    [Pg.421]    [Pg.367]    [Pg.20]    [Pg.253]    [Pg.357]    [Pg.357]    [Pg.717]    [Pg.766]    [Pg.808]    [Pg.812]    [Pg.153]    [Pg.8]    [Pg.96]    [Pg.386]    [Pg.142]    [Pg.282]    [Pg.206]    [Pg.279]   
See also in sourсe #XX -- [ Pg.66 ]




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Free solution

Free-solution separations

Rates separation

Separable rate

Separators solutions

Solute separation

Solution separations

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