Eluant potassium hydroxide

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. 

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... 

Potassium hydroxide is a suitable eluant for the determination of inorganic anions with pJC values above 7. Due to the high pH value of the mobile phase, even weak adds are completely dissodated and, thus, may be detected via their conductivity. However, the conductivity of the analytes is lower than that of the mobile phase, so that negative signals are observed for these spedes. This method is called indirect conductivity detection. 

A much more elegant way to prepare hydroxide eluants has recently been introduced by liu et al. [148]. The respective device was commercialized under the trade name Eluant Generator. The most important part of this module is a cartridge, in which potassium hydroxide is generated by means of electrolysis. As schematically depicted in Fig. 3-146, such a cartridge consists of an electrolyte reservoir, which is filled with KOH solution (c = 4 mol/L) and connected to an electrolysis chamber via a stack of cation exchange membranes. 

Alternatively, a strongly conducting eluant may be used. In this case, elution of the solute ions is associated with a negative conductivity change. This indirect detection method is applied to the separation of anions with a potassium hydroxide eluant [7]. A corresponding chromatogram is displayed in Fig. 7-2. This indirect detection method is also utilized in the analysis of mono- and di valent cations, which are eluted by dilute nitric acid or nitric acid/ethylenediamine mixtures. 

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 ... 

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