Cation-exchange columns volumes

Accurately weigh about 6 g NaCl and dissolve in distilled water. Pass the solution through a well-rinsed cation exchange column (Dowex 50W) in the hydrogen form. The equivalent amount of HCl is washed from the column (in 10 column volumes) into a volumetric flask and made up to volume. Equivalent weight is the formula weight. 

Once all the metal has been dissolved, the solution is passed through a cation exchange column (AG 50W-X8, 100-200 mesh BioRad Laboratories). A bed volume of as little as 40 ml has been used successfully in this work. The resin removes the cations present from the large quantity of molybdate and any other anions that might be present. The column is now converted to the ammonium form by passing 0.5 M NH Cl through the column until the pH of the... 

The solution and precipitate were separated by filtration. Qualitative analysis of the precipitate showed that it contained cerium(III) and sulfate ion. [No precipitate appeared when m-bisoxalatodiaquochromate(111) ion and cerium(IV) were allowed to react at this acidity under conditions where the sulfate and/or cerium concentrations were somewhat lower.] The filtrate, including washings, was diluted to a measured volume, and two measured aliquots of this solution were withdrawn for study. The first aliquot was passed onto a cation exchange column in the hydrogen form. Elution with 1M sulfuric acid left a small dark violet band of hexaaquochromium(III) ion at the top of the column, while the rest of the chromium passed through the column. [In separate experiments it was confirmed that the Cr(OH2)fe+3 ion is retained as a dark violet band at the top of the resin when the resin is eluted with 1M sulfuric acid. This is in agreement with the observations of King and Dismukes (23).] Analysis of the effluent solution showed that 4 to 5% of the chromium had been retained by the column. 

Fig. 1. Simultaneous separation and detection of anions and cations on a latex agglomerate column. Column Dionex HPIC-CS5 cation exchange column (250X2 mm) with precolumn HPIC-CG5 (50 X 4 mm) eluent 0.5 mM copper sulfate, pH 5. 62 flow rate 0.5 ml/min sample volume 20 gl containing 0.1 m M of each ion detection two potentiomet-ric detectors equipped with different ion-selective electrodes in series. Peaks (1) chloroacetate, (2) chloride, (3) nitrite, (4) benzoate, (5) cyanate, (6) bromide, (7) nitrate, (8) sodium, (9) ammonium, (10) potassium, (11) rubidium, (12) cesium, (13) thallium. Reprinted with permission from [10].

FIGURE II IgG elution volume from a cation-exchange column as a function of the column saturation load was (a) 10% of column saturation or 6 mg per milliliter of resin, (b) 20% saturation, (c) 50% saturation, and (d) 100% saturation or 60 mg per milliliter of resin. As resin CM HyperD F was used, the loading conditions and elutions were as described in Fig. 10. 

Brioch, DeMayo, and Dal Cortivo u describe a semi-automated method for the separation and determination of narcotics mixed with mannitol and lactose. A SE-Sephadex C-2S> cation exchange column buffered with pH U.6 phosphate buffer is used to effect separation, followed by ultraviolet monitoring of the column effluent for the detection of the narcotics, including meperidine. A retention volume of 71.1 ml. was reported for meperidine when eluted with phosphate buffer from a 50 x 0.9 cm. column packed UO cm. high. 

Another valuable application of ion-exchange resins involves concentrating ions from a very dilute solution. Thus, traces of metallic elements in large volumes of natural waters can be collected on a cation-exchange column and subsequently liberated from the resin by treatment with a small volume of an acidic solution the result is a considerably more concentrated solution for analysis by atomic absorption or ICP emission spectrometry (see Chapter 28). 

Tanaka and Ishizuka [3] studied the separation of acids by ion-exclusion chromatography on a modern, high performance cation-exchange column. Hitachi cation exchange resin, 8 % cross-linking, 18 2 pm particle size was used. Retention volumes of acids were obtained at 50 °C using water as the eluent. These are given in Table 8.1. 

Retention Volumes (cnP) of Some Methyl Aldofiiranosides on Cation-exchange Columns ... 

In order to obtain a solution in 2M HPTS (p-toluenesulfonic acid), the [Mo303S(aq)] solution in IMHCl is diluted to five times its original volume with water, and was absorbed to Dowex 50W-X2 cation exchanger (column diameter 2 cm, length 10 cm). The column is then washed with O.IMHPTS to remove Cl" ion ( 200mL the column can be washed rapidly, and full removal of Cl ion is checked by AgN03 solution) and eluted slowly with 2M HPTS. Typically 120 mL of a 0.04M (per trimer) red solution is obtained. 

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