Elution with electrolyte solution

Elution of Lignin Sulfonates with Electrolyte Solution and Calibration of Columns... 

Because of the polyelectrolyte properties of lignins, elution is performed with electrolyte solutions. If the lignins are water soluble and the column... 

Relative molecular mass distributions for components of biochemical and polymer systems can be determined with a 10% accuracy using standards. With biochemical materials, where both simple and macro-molecules may be present in an electrolyte solution, desalting is commonly employed to isolate the macromolecules. Inorganic salts and small molecules are eluted well after such materials as peptides, proteins, enzymes and viruses. Desalting is most efficient if gels with relatively small pores are used, the process being more rapid than dialysis. Dilute solutions of macro-molecules can be concentrated and isolated by adding dry gel beads to absorb the solvent and low RMM solutes. 

Figure 6 shows that the proteins used for calibration elute in the same way as lignin sulfonates, which justifies the use of proteins as calibration standards. A comparison between Figures 4 and 6 shows that elution with an electrolyte solution fractionates lignin sulfonates in the range 3 000-80 000 dalton, but that elution with water fractionates those in the range 20 000-100 000 dalton. 

Fibre or micromembrane suppressors of high ionic capacity have now taken over from chemical suppressors. With dead volumes in the order of 50 pi, they allow gradient elution with negligible drift in the baseline. Figure 4.8a shows the passage of an anion A- in solution in a typical electrolyte used for anionic columns through a membrane suppressor. 

The essential advantage of the application of resins with neutral anchor groups — compared with those resins where ionic groups are fixed — is that one only needs pure solvents or mixtures of solvents instead of electrolyte solutions for the chromatographic elution of the metal ions . For example, the isotopic exchange reaction between Ca and using a resin with [2b.2.2] anchor groups is as... 

Commercial ion chromatography instrumentation thai requires no suppressor column is also available, 1 his approach depend.s on the small differences in conductivity between sample ions and the prevailing clucni ions. To amplify these differences, low-capacity exchangers arc used that permit elution with solutions with low electrolyte concentrations. Furthermore, eluents of low conductiviiy arc chi>scn. ... 

All these studies on chromatographic size exclusion separations on neutral separation media and selectivity of transportation of ions through membranes were carried out with very dilute electrolyte solutions. Only Rona and Schmuckler [135] examined Dead Sea concentrated brine on a Bio-Gel P-2 (crosshnked polyacrylamide) column and obtained a Hthium-enriched fraction free of calcium and magnesium. Bio-Gel P, however, is known to retain cations and probably enters hydrogen-bond interactions between the anions and the amide hydrogen. The elution order of chlorides was thus different from that expected for pure SEC, namely, K, Na, Li, Mg, and Ca, all, however, emerging before the hold-up (dead) volume of the column. 

Figure 12.12 Redistribution of CaCl2 and HCl within the aqueous solution passed through a column with dry carbon D4609 and then eluted with n-butanol. Initial concentration of each electrolyte in the feed, 0.6 N. (After [171].)...

Sulfur-containing macrocycles bound to silica gel are highly selective concentration and purification ligands for Pd", Hg" and Ag. These immobilized macrocycles efficiently removed Au " and Pd" from solutions of HCl and FeCls. Similarly, Ag+, Au" and Pd" were separated by these columns and selectively eluted from the columns with purities of 99.9%. It was also shown that Pd" can be removed from industrial silver electrolyte solutions with 99.9% purity in one pass through these columns <91ANC1014>. 

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