Cation elution curve

Figure 2. Cation elution curves (left scale) and lead breakthrough curve (right scale) on chabazite tuff bed in its original cationic composition Feed composition 110 mg-1 Pb feed flow rate 6 ml-min...

Fig. 10. Elution curves for trivalent cations (Eu), and for Zr, Ta, Nb, and Pa from Aliquat336/Cf -Voltalef (1 5) columns (1.6x8 mm) in ARCA II. The activities are fed onto the column in 10 M HC1. This is followed by separate elutions of a Ta fraction (6 M HC1), a Nb fraction (4 M HC1), and a Pa fraction (0.5 M HC1). Reproduced from [32] with the permission of Oldenbourg Verlag.

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.

To overcome the difficulties of ESI-MS, Simonsick and Prokai added sodium cations to the mobile phase to facilitate ionization [165,166]. To simplify the resulting ESI spectra, the number of components entering the ion source was reduced. Combining SEC with electrospray detection, the elution curves of polyethylene oxides) were calibrated. The chemical composition distribution of acrylic macromonomers was profiled across the molar mass distribution. The analysis of poly(ethylene oxides) by SEC-ESI-MS with respect to chemical composition and oligomer distribution was discussed by Simonsick [167]. In a similar approach aliphatic polyesters [168], phenolic resins [169], methyl methacrylate macromonomers [169] and polysulfides have been analyzed [170]. The detectable mass range for different species, however, was well below 5000 g/mol, indicating that the technique is not really suited for polymer analysis. 

Schweich, D., Sardin, M., and Gaudet, J. P. (1983) Measurement of a Cation Exchange Isotherm from Elution Curves Obtained in a Soil Column Preliminary Results, Soil Sci. Soc. Am. J. 47, 32-37. 

The last four actinides (Am, Cm, Bk, and Cf) have +3 as their most stable valency state in solution, just as the rare earth elemrats, and their chemistry is very similar to that of the lanthanides. This similarity in solution has been commonly used for id tification of a particular actinide Figure 16.7 shows elution curves for lanthanides and actinides from a cation exchange column. 

Better separation of zirconium and hafnium by elution from a cation-exchange resin is claimed by Benedict et al. who used 0-09 M citric acid and 0-4S M nitric acid as eluting agent, after absorbing from 0-8 M sulphuric acid. The zirconium eluted first. The elution curve is shown in Fig. 3.17. 

Fm, the daughter of the new element, was collected using the recoil technique, one atom at a time, and identified as Fm by their position in the cation-exchange elution curve. A half-life of 3 s was assigned to No at that time. However, it is now known that the 3 s radioactivity was No produced in the Cm ( C,4n) reaction the used target contained 20 times more Cm than Cm. No is now known to have 55 s half-life. The errors in this experiment indicate the difficulty associated with one-atom-at-a-time studies. In subsequent chemical experiments, it was found that the most stable oxidation state of element 102 in solution was 2+. The element was named nobelium after Alfred Nobel. 

SP-Sephadex C-25 saturated with a A-complex cation was packed in a glass column. A racemic complex anion was eluted through the column with 30% aqueous ethanol. The eluate was fractionally collected, and the AB and CD spectra were recorded. The elution curves were obtained in this way when necessary, but the degree of resolution was generally so low that only the elution orders were determined in most cases. 

Portions of the appropriate hydrolysis mixtures, prepared as described below, were loaded onto the tops of the columns and the excess electrolyte, as well as all nonadsorbed complex species, removed by washing first with distilled water and then with 0.05 M sodium perchlorate. Adsorbed species were eluted individually from the column by gradually increasing the concentration of sodium perchlorate in the eluting solution. The effluent from the columns were collected in small fractions, usually from 15 to 25 ml, which were stored in the dark at 0° until used in subsequent experiments. Typical elution curves from the anion and the cation-exchange resin columns are shown in Figs. 1 and 2, respectively. Detailed procedures for the separation of individual species are given below. 

Fig. 2. Ion exchange elution curve showing separation of neutral and cationic cyano-aquochromium(III) complexes. I. Cr(CN)3(H20)3 II. Cr(CN2(H20)4 III. unidentified species IV. Cr(CN)(H20)i+ and V. Cr(H20)i+.

In order to clarify this point, GPC measurement of the polymers was carried out and the elution curves are shown in Fig. 1. The curve obtained with TiClg-(CgHg)gAlCl catalyst gave the polymodal, and it was not the same as those obtained with (C2Hg)2AlCl or TiClj catalyst, indicating that the reaction products also serve as the cationic active species. 

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... 

Fig. 10.2 HPLC elution curve of Bk and Ce using 0.5 M ammonium a-hydroxyisobutyrate on a cation-exchange column [54]. Reproduced with permission of the authors and Pergamon Press.)...

Elution time, 19 EMIT, 340 Energy filter, 295 Enzyme conjugate, 336 Equivalent conductance, 70 Error curve, 388 Exact value, 385 Exchanging anion, 66 Exchanging cation, 66 Experimental error, 385... 

Belal et al [40] reported on the use of flame atomic absorption spectroscopy (FAAS), coupled with ion-exchange, to determine EDTA in dosage forms. EDTA is complexed with either Ca(II) or Mg(II) at pH 10, and the excess cations retained on an ion-exchange resin. At the same time, the Ca(II) or Mg(III) EDTA complexes are eluted and determined by AAS. Calibration curves were found to be linear over the range of 4-160 and 2-32 pg/mL EDTA when using Ca(II) or Mg(II), respectively. The method could be applied to eye drops and ampoules containing pharmaceuticals. Another combined AAS flow injection system was proposed for the determination of EDTA based on its reaction with Cu(II). The calibration curve was linear over the range of 5-50 pg/mL, with a limit of detection of 0.1 pg/mL [41]. 

It is worth noting that no exothermic peak was obtained on Cs salts compared to their acid analogues, showing their greater thermal stability. Note also that the content of protons, as calculated from the constitutional water evolved between 200 and 450°C, is reliable for the acid samples (close to 4) whereas it varies between 1.6 and 2.8 instead of 1.5 as expected for Cs salts. The TGA curves shown in Figure 1 illustrate this phenomenon, in particular for Cs salts for which water loss occurred up to 600°C, with a small step between 450 and 500°C. This water loss between 200 and 600°C corresponds both to water adsorbed on Cs cations and to dehydroxylation of constitutional water, i.e. to the elution of protons. This is why the number of protons given in Table 2 is more than 1.5 as expected... 

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