Eluting agents

Sodium trimetaphosphate was used as an eluting agent for the removal of heavy metals such as Pb, Cd, Co, Cu, Fe, Ni, Zn and Cr from aqueous solutions. Distribution coefficients of these elements have been determined regarding five different concentrations of sodium trimeta phosphate (3T0 M 5T0 M 0.01 M 0.05 M 0.1 M) on this resin. By considering these distribution coefficients, the separation of heavy metals has been performed using a concentration gradient of 3T0 - 5T0 M sodium trimetaphosphate. Qualitative and quantitative determinations were realized by ICP-AES. 

RT mp, explds below mp. Prepn is by reacting methyldiacetyleneMgBr in eth under N2 with dry Cu chloride. The mixt is extd with aq ammonium chloride, coned to 100ml and cooled to —78°. The crude yield is purified by chro-maty on A1 oxide using 1 2 eth-petr eth as the eluting agent... 

The effectiveness of the elution step can be tailored by using a single eluent, pulses of different eluents, or eluent gradients. These systems are generally characterized by mild desorption conditions. If the eluting agent is bound to the protein, it can be dissociated by desalting on a gel filtration column or by diafiltration. 

Kutun, S. and Akseli, A., New elution agent, sodium trimetaphosphate, for the separation and determination of rare earths by anion-exchange chromatography, /. Chromatogr. A, 847, 261, 1999. 

The applications of ion-exchange chromatography are exemplified by the selection shown in Table 4.18. Among the most notable are the separation of lanthanides and actinides using a citrate, lactate or EDTA eluting agent ... 

The efficiency of fractionation by gel chromatography not only depends on the type of gel but also on the dimensions of the column. The internal volume V, of the gel pores is determined by the amount of dry resin used and by its swellability, which in turn depends upon the eluting agent. The total volume of the gel bed V, is thus made up of the volume of the gel framework, the internal volume V, of the gel, and the external volume Vq between the gel particles. The external volume Vq is identical with the elution volume of a substance with a molecular weight above the exclusion limit. Macromolecules of this size cannot penetrate the network but pass through the column unimpeded. Vq can thus be readily determined. 

A solution of 250 mg of poly(acrylamide) from Example 3-9 in 25 ml of distilled water is introduced at the top of the column. At the same time the collection of the eluate is commenced, taking 10 ml portions (measuring cylinder) for each fraction.Theflow time under these conditions is about 10 ml/h. When the meniscus of the poly(acrylamide) solution reaches the gel layer, distilled water is added to the column as eluting agent. 

However, in order to remain reasonable, a more effective eluting agent, such as the solution of 0.1% ammonium citrate at pH 5.0 - 8.0 which gives thejhn (Cit) ]" species had to be used. This system was utilized to separate kilogram quantities of rare earths with a purity better than 99.99% but because of its low total capacity it was commercially unattractive. 

Eluant or Eluent, also called Elution Agent. 

Figure 15.8 Original elution data corresponding to the discovery of mendelevium, February 18, 1955. The curves for einsteinium-253 (given the old symbol E253) and californium-246 are for a-particle emission. (Dowex 50 ion exchange resin was used, and the eluting agent was ammonium a-hydroxyisobutyrate.)...

Some time s(especi ally when only a few compds are in a mixt), it is more convenient not to extrude the column, but instead to subject it to a more prolonged washing directly in the tube. This treatment, called elution, will usually separate the components more efficiently into wider bands and these may then be removed(together with solvents) and collected separately in clean receivers as the percolation thru the column continues. Solvents used in washing the column are called eluents or elution agents and they may be ales, eth, acet, dichloroethane, dichloro-methane, chlf, et acetate or petr ether(Refs 58 78)... 

Traditionally, isomers formed by polyamines and inert metal centres have been separated by fractional crystallization. More recently, the techniques of column chromatography have been used, especially for Co111 hexamines.31,3S Both geometric and optical isomers can be separated by judicious use of eluting agents and under favorable conditions isomers occurring at the 1 % level can be isolated. 

Figure 8.1. Chromatograms produced on a 100 mm column of an amino acid analyser with 0.3 N sodium citrate solution (pH 7.00) as eluting agent (a) standard solution containing 1 unol/ml of each amino acid (b) 30 g of cabbage extract purified with Dowex 50-X8 in the ammonium form (0.97 mg of S-methylmethionine) and (c) the same sample as for (b) but after treatment at pH 10.0 for 30 minutes at 120 C. MMS S-methylmethionine, fils histidine, lys lysine, orn ornithine, arg arginine. From [12]...

Carbonate has been determined in high priority water in amounts down to 0.02pg L 1 by ion chromatography on Zipax SAX phthalic acid or mucomic acid at pH 6.5 and 7.2 as eluting agent and an indirect ultraviolet detector set at 321pm [125],... 

The resulting clear filtrate is passed through a 30 X 700-mm. chromatographic column which is one-third filled with silica gel.J With low-boiling petroleum ether as the eluting agent and a rapid flow rate, 200-ml. fractions are collected until no... 

Step 2. Write a procedure for testing other eluting agents in the style of the experiments in this laboratory manual to delineate each step in sufficient detail. 

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