Separation Am

Kilogram quantities of americium as Am can be obtained by the processing of reactor-produced plutonium. Much of this material contains an appreciable proportion of Pu, which is the parent of Am. Separation of the americium is effected by precipitation, ion exchange, or solvent extraction. 

If I know that the compound is not soluble in aqueous solvents, I will probably select a silica column and a chloroform/hexane mobile phase. Separations of proteins will take me first to a TSK-3000sw column and a lOOmM Tris-phosphate pH 7.2 mobile phase unless I am separating soluble enzymes then I use a TSK-2000sw column. 

Figure 2. Integrated flowsheet used at the ALKEM plant for plutonium nitrate conversion combined with 241 Am separation and conversion...

M DOP, the mixing time being 10 minutes. Under these conditions the Eu/Am separation factor is about 30, and triple extraction transfers 97 europium into the organic phase. 90% Am stay in the aqueous phase, where the content of Eu is no higher than 3%. Americium can then be quantitatively extracted by 0.04 M DOP toluene solution, the phases being mixed for 45 minutes. 

In gais chromatography (GC), open-tubular caplllaury columns cam produce much more theoretical plate numbers tham conventional packed columns. Open-tubular capillary columns have been examined am separation tools also in liquid chromatography(LC)(8-12). Coated columns, ca. 20 m X 10-30 vim l.d., produced theoretical plate numbers in excess of 100,000 but long-term stability of these columns was scxnewhat poor even if the mobile phame is saturated with the mobile phase. Accordingly chemically bonded or immobilized stationaury phatses should be preferred. 

Metabolite quantitation in humans and two species of preclinical animals at Cmax in plasma is shown in Figure 16.11. UPLC—AMS separated and quantified fractions of variable width that depended on metabolites expected from the animal species. UV absorbance (dashed lines in the figure) monitored resolution and provided a marker near 8 min for one metabolite spiked into the plasma samples before separation. AMS data is plotted as the fraction of the total eluted isotope signal in the trace on both linear and log scales for 18 compounds that produced peaks in one or more of the three species. Multiple metabolic differences are noted not only between the human and the animals but also between the two animal species. Specifically, the metabolites included as a spike, M , is disproportionately found in humans at more than 10% of the total content and only minimally, but distinctly, in species 2. Chromatographic conditions broadened the UV metabolite peak in species 1 with resolution also lost in leaving only a hint of the metabolite presence. M is the only other metabolite exceeding 10% of total in human plasma in this... 

Alkyl pyrocatechol extractants provide greater group separation factors. Eu/Am separation factors of 70 have been reported for a non-equilibrium extraction in the system 4-(a,(z-dioctylethyl)-pyrocatechol/NaOH/DTPA (diethylenetriamine-N, N, N, N, N-pentaacetic acid) (or DTPP - diethylenetriamine-N, N, N, N", N"-pentameth-ylenephosphonic acid) (Karalova et al. 1982). The separation factors are based mainly on the difference in the rates of the metal-DTPA (or DTPP) complexation equilibria for Eu and Am. They are therefore highly dependent on the contact time. A principal limitation of the practical application of such a separation scheme is the relatively long contact times (> 10 min) required for extraction. However, the slow equilibration compares favorably with that for other lanthanide-actinide separation processes (e.g. TALSPEAK, section 7). 

Closs G L and Miller R J 1979 Laser flash photolysis with NMR detection. Microsecond time-resolved CIDNP separation of geminate and random-phase polarization J. Am. Chem. Soc. 101 1639—41... 

Liddell P A, Kuciauskas D, Sumida J P, Nash B, Nguyen D, Moore A L, Moore T A and Gust D 1997 Photoinduced charge separation and charge recombination to a triplet state in a carotene-porphyrin-fullerene triad J. Am. Chem. Soc. 119 1400-5... 

Resolution 10% valley definition, m/Am. Let two peaks of equal height in a mass spectrum at masses m and m/Am be separated by a valley that at its lowest point is just 10% of the height of either peak. For similar peaks at a mass exceeding m, let the height of the valley at its lowest point be more (by any amount) than 10% of either peak height. Then the resolution (10% valley definition) is m/Am. It is usually a function of m therefore, m/Am should be given for a number of values of m. 

Three important parameters for mass spectrometers are mass resolution, mass range, and sensitivity. The resolution, R, required to separate two ions of mass m and (m + Am) is given by equation 1. 

Farbar [Trans. Am. Soc. Mech. Eng., 75,943-951 (1953)] describes how a venturi meter can be used to measure solids flow rate in a gas-solids mixture when the gas rate is held constant. Separate calibration curves (solids flowversus differential) are required for each gas rate of interest. 

Knitted wire mesh serves as an effective entrainment separator when it cannot easily be foiiled by sohds in the liquor. The mesh is available in woven metal wire of most alloys and is installed as a blanket across the top of the evaporator (Fig. ll-122d) or in a monitor of reduced diameter atop the vapor head. These separators have low-pressure drops, usually on the order of 13 mm [ M in) of water, and collection efficiency is above 99.8 percent in the range of vapor velocities from 2.5 to 6 iti/s (8 to 20 ft/s) [Carpenter and Othmer, Am. nsi. Chem. 

FIG. 13-19 Liqiiid-phase activity coefficieuts for au n-fieptaue-toliieue system at 101,3 kPa (1 atm), [Henley and Sender, Eqiitlikriiim-Stage Separation Operations iu Chemical Engineering, Wiley, New York, 1981 data ofYerazunis et al., Am, Inst, Ghem, Eng, J, 10 660 (1964). ]... 

FIG. 13-41 Comparison of rigorous calcnlations with Gilliland correlation. [Henley and Seader, Eqnilihrinm-Stage Separation Operations in Chemical Engineering, Wiley, New York, 1981 data of Van Winkle and Todd, Chem. Eng., 78(21), 136 (Sept. 20, 1971) data of Gilliland, Elements of Fractional Distillation, 4th ed., McGraw-Hill, New York, 1950 data of Brown and Maiiin, Trans. Am. Inst. Chem. Eng., 35, 679 (1.93.9) ]... 

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