The CL Resin is used for the separation of chloride and iodide and is based on an extraction system that is selective for platinum group metals, gold and silver. The selectivity for halides is introduced by loading the resin with silver.
Table1 shows DW values of selected cations on the CL Resin, for practical reasons sulfuric acid was chosen as extraction medium. It can be seen that the CL Resin has high selectivity for Pd and Ag, whereas the DW values of the other elements tested are low. Ag further shows high DW values over a wide pH range (from 1M H2SO4 to dilute sulfuric acid (pH 5)). It will thus be extracted or remain fixed over a wide range of pH values.
|Analyte||Extraction condition||Dw, mL.g-1|
|Ag||Sulfuric acid, pH 3||600000|
|Ag||Sulfuric acid, pH 5||350000|
Table 1: DW values CL Resin of selected cations in sulfuric acid.
The loading of the resin with silver cations allows good selectivity for anions, especially halides, forming sparely or insoluble Ag complexes. DW values for chloride and iodide on the silver loaded CL Resin in 1M H2SO4 were deter-mined to be 1600 and 1980 respectively. Both are thus well retained under those conditions. The CL Resin used for the DW experiments was loaded with 20 mg Ag+ per g of CL Resin prior to the extraction experiments which corre-sponds to a typical working capacity. The capacities for chloride and iodide of the silver loaded resin under these conditions are: 16.3 +/- 1.6 mg iodide per 2 mL column (approx. 25 mg iodide per g resin) and 4.3 +/- 0.2 mg chlo-ride per 2 mL column (approx. 6.5 mg chloride per g resin). Higher capacities for halides can be obtained by increas-ing the silver load of the CL Resin.
In order to evaluate best suited conditions for the separation of chloride and iodide DW values of chloride and iodide were determined on silver loaded CL Resin in varying SCN- and S2- concentrations: Fig. 1 and 2 show the obtained results.
Chloride can be easily eluted from the resin using SCN- solutions whereas iodide remains fixed. Iodide can then be eluted from the resin using a high concentration solution of S2-. Based on this information, a method for the separa-tion of chloride and iodide was developed and optimized by Zulauf et al. ; fig. 3 schematically shows this method. In order to assure that both chlorine and iodine are present as chloride and iodide, the sample might be loaded from a sulphuric acid solution containing 0.1M SnSO4 as reducing agent. This is especially important in case of chlorine since e.g. chlorate is not fixed on the resin, whereas iodate is extracted, as could be expected from silver salt solubility data.
The sample is preferably loaded onto the silver loaded CL Resin from 1M H2SO4 (slightly acidic or even neutral con-ditions are also acceptable). During a first rinse (deionised water) matrix elements and potential inter-ferents are removed from the column. Chloride is then eluted in a small volume of NH4SCN or NaSCN.
During method optimization it was shown that rinsing the column with a dilute alkaline solution before iodide elution lead to a strong increase of the iodide yield. Therefore, the CL Resin column is accordingly rinsed with 1% NaOH be-fore iodide is finally eluted in a small volume of a Na2S solution (Remark: all work with the Na2S solutions should be performed under a fume hood, including the addition of the liquid scintillation cocktail.).
The small elution volumes used for elution allow for direct measurement of the obtained fractions by LSC (Remark: some LSC cocktails reduce traces of Ag+ co-eluted from the column resulting in „blackened‟ LSC samples; it is thus advisable to test your cocktail before use).
CL Resin is manufactured in two particle sizes (50-100μ, and 100-150μ) and is sold in bottles or ready to use in prepackaged columns (for gravity flow).
Source for all published data:
(1) A. Zulauf, S. Happel, M. B. Mokili, A. Bombard, H. Jungclas: Characterization of an extraction chromatographic resin for the separation and determination of 36Cl and 129I. J. Radanal Nucl Chem, 286(2), 539-546 (DOI: 10.1007/s10967-010-0772-5)
|Particle Size||Bottles||Part Number|
|100-150 μ||25 grams||CL-B25-A|
|Columns (2mL)||Part Number|
|Package of 20||CL-C20-A|
|Package of 50||CL-C50-A|
|Package of 200||CL-C200-A|
|Particle Size||Bottles||Part Number|
|50-100 μ||25 grams||CL-B25-S|