Elution curves, from short

Fig. 17. Elution curve for short-lived W isotopes modeling the seaborgium separation [52J in ARCA II using a solution of 0,1 M HNO3/510 4 M HF with a flow rate of 1 mL/min. The 1.6x8 mm columns are filled with the cation-exchange resin Aminex A6. Reproduced from [52] with the permission of Oldenbourg Verlag.

On examination of the curve in figure 4 the problem associated with high efficiencies becomes apparent. The elution time for the short column having about 3500 theoretical plates is only just about one half minute. The elution time from the 1.5 million plate column, however, is about 54 days, a rather long time to wait for a chromatographic separation. It is also seen that the higher the efficiencies that are required (the more difficult the separation problem) the longer the separation time and this is inevitable as a result of practical limits to the column inlet pressure. 

Fig. 3.3 Elution curve of Hf isotopes resulting from multiple cycles of a short bombardment followed by a longer beam-off interval [11]. The hatched area (the activity produced at beam-on) equals that under the histogram.

A procedure for the rapid separation of berkelium from other actinides, lanthanides, and fission products was developed in order to measure the decay properties of short-lived isotopes [54]. Bk and Ce were separated from other elements using solvent extraction with HDEHP followed by cation-exchange high-pressure liquid chromatography (HPLC) using a-hydroxyisobutyrate as the eluant. The elution curve, showing a clean separation of Bk from Ce, is shown in... 

Adjust an accurately weighed sample, as needed, with 20% aqueous sodium chloride to obtain a Sample Solution with a solids content of 36%. Transfer a 20-g aliquot of the Sample Solution into a 20-mL Extrelut NT column (EM Science, Gibbstown, NJ), or equivalent, and allow it to equilibrate for 15 min. Elute the column with 150 mL of ethyl acetate, collecting the eluent in a 250-mL short-neck, round-bottom flask with a 24/40 joint. Using a rotary evaporator at 50°, concentrate the eluent to a volume of approximately 3 mL. Add 0.5 mL of Internal Standard Solution to the eluent, transfer this mixture to a 4-dram screw-cap vial, and dilute to a volume of 5.0 mL. Inject 1 pL into the gas chromatograph, measure its response area ratio of 3-CPD to the Internal Standard Solution, and determine from the standard curve the micrograms of 3-CPD in the 20-g aliquot taken. l,3-Dichloro-2-propanol (DCP)... 

The curves in Fig. 24 show the effect of addition of fatty acids of different chain length on the NaTDS micelles [43]. The free energy solubilization in the micelle will be larger for long chain fatty acids, in comparison to short chain acids. This is seen clearly from the data in Fig. 24, where the elution volume for oleic acid (= 22 fraction number) is much lower than for C6-acid (= 56 fraction number). Since the solubility of oleic acid in water is very low, it would be expected to be present entirely in the micellar phase. 

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