Eluant hydroxide

In IC this problem of electrolyte background is overcome by means of eluant suppression. Thus in the above example of sodium and potassium analysis, if the effluent from the separating column is passed through a strong base anion exchange resin in the hydroxide form (suppressor column) the following two processes occur ... 

If necessary, adjust the pH to 8.4-8.5 using boric acid crystals or 0.1 M sodium hydroxide the pH of the eluant is critical. 

Concentration of Model Compounds in the Absence of Humic Substances at 120-150 Bed Volumes/h. Resin studies using XAD-4 quaternary resin in the hydroxide form were performed several times at 150 bed volumes/h at various concentrations of the model compounds. The primary objective of these studies was to make a preliminary evaluation of the separation and concentration capacity of XAD-4 quaternary (OH ) resin for the model compounds. Emphasis was thus placed on the measurement of each compound in the final eluant concentrate. However, whenever convenient, analyses were also made of the aqueous effluent and reservoir to provide for more complete mass balances. 

Eluants other than carbonate/bicarbonate have also found wide application in many environmental and nonenvironmental analyses. Some common eluants are listed in Table 1.11.2. Sodium hydroxide solution has now become an eluant of choice for many ion chromatography analyses using suppressed conductivity detection. The schematic representation of the method is outlined in Figure 1.11.2. 

For naphthalene black there is a perfect eluant, composed of equal parts ethanol and 0.5 N sodium hydroxide. The alkaline pH and the ethanol are required to overcome adsorption of protein to paper, but as alkaline solutions of the dye are very unstable, probably due to the presence of traces of heavy metal ions, the addition of 500 mg of Com-plexon (EDTA) per liter is required (D3 Fig. 26). In this condition an alkaline solution of amido black is stable for indefinite periods of time. 

Although many columns and eluants can be used for gradient elution, the conditions used in Figs. 2.16 and 2.17 are recommended as a good starting point. The HPIC-ASSA (5 i) separator with sodium hydroxide eluant provides the optimum combination of efficiency, selectivity, and speed without an unacceptable baseline slope. If fewer ions than the 36 shown in Fig. 2.16 need to be separated, the gradient steepness can be increased to reduce the run time. 

The copper phthalate eluant was prepared by mixing a solution of cupric acetate with an excess of potassium hydroxide and filtering the resulting cupric hydroxide precipitate. The cupric hydroxide precipitate was then mixed with an equimolar amount of phthalic acid and heated gently overnight to produce copper phthalate. 

Scrape off each subsidiary color and extract with 3- to 5-mL portions of 50% aqueous ethanol until no color remains on the gel by visual inspection. Dilute each sample to 13 to 15 mL, add a few drops of ammonium hydroxide, and record the final volume. Repeat this procedure for the band of Erythrosine using 10- to 20-mL portions of 50% ethanol, and dilute the eluant to 250 mL in a volumetric flask after adding enough... 

Fig. 8.1.1. Elution of lignosulfonates on Sephadex G-75 with 0.25 M calcium chloride as eluant (upper curve). Elution of kraft lignins on Sephadex G-50 with 0.5 M sodium hydroxide as eluant (lower curve). (Forss et al. 1976)...

Cation Analysis (Figure 9.6a). Suppose a dilute acid HY is used to elute a cation mixture in the order B , C, D. The suppressor column contains a finely graded conventional anion exchange resin in, say, the hydroxide form. Prior to elution of ion B, the suppressor column sees only the eluant HY, and the following exchange takes place ... 

Anion Analysis (Figure 9.6b). For anion analysis the analogous principles apply, only now the eluant is, for example, the hydroxide or mixed carbonate/bicarbonate ion and the suppressor column a cation exchange resin in the hydrogen form, thereby suppressing conductivity by the formation of water and dissolved carbon dioxide respectively. 

C. (+)-(lS,2S>-Cyolopvopane-ljZ-diBarboxylio aoid. (-)-Dimenthyl (lS,2S)-cyclopropane-l,2-dicarboxylate (4.06 g, 10 mmol, +17.8°) Is dissolved in 20 ml of a 10% potassium hydroxide solution in 9 1 methanol/water In a 50-mL, one-necked, round-bottomed flask equipped with a magnetic stirring bar. The solution is heated at 60°C with an oil bath. Progress of the reaction is monitored by TLC on silica gel, using 1 1 hexane/ethyl acetate as eluant (Note 15). After about 4 hr the resulting two-phase mixture Is diluted with 20 mL of water and extracted with three 40-mL portions of ether (Note... 

In situations when analysis is required to establish the presence and identity of calystegines in a plant extract it is not necessary to utilize a complex series of chromatographic separations. The plant material can be extracted with methanol or methanol-water and passage over a Dowex 50W-X8 column with dilute ammonium hydroxide as eluant provides substantial purification, yielding the alkaloid fraction, including other polyhydroxy alkaloids, contaminated only by basic amino adds. The extract can thus be rapidly prepared for analysis [29,30]. 

MS hydroxide in the eluant stream at a ammonium acetate in the eluant... 

For the separation of a mixture of cations the eluant commonly used is a dilute solution of HCl. The analytical column achieves the required separation while the scrubber column, in this instance a quaternary ammonium hydroxide resin, combines with the ions in the eluant and at the same time converts analyte ions to their hydroxides. The configuration of the instrumentation is depicted in Figure 6.44. 

Nebramycins, closely related aminoglycosides produced by Streptomyces tenebrarius, have been separated on a neutral polystyrene-based column, with aqueous sodium hydroxide as eluant and... 

We compared in sect. 3.1 the holdback factors for several carboxylic and aminopolycar-boxylic acids that have been (or could be) used for lanthanide separations. It is clear that among the carboxylic acid eluants, a hydroxide group on the a-carbon atom is necessary for consistent performance across the series. One might expect that the proximity of the OH group creates the possibility of simultaneous coordination of both a carboxylate oxygen and the hydroxide, thus creating a chelate complex of enhanced stability. However... 

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