Chelex-100 resin

Ion exchange column. Prepare the Chelex-100 resin (100- 500 mesh) by digesting it with excess (about 2-3 bed-volumes) of 2M nitric acid at room temperature. Repeat this process twice and then transfer sufficient resin to fill a 1.0 cm diameter column to a depth of 8 cm. Wash the resin column with several bed-volumes of de-ionised water. 

Pietra, R., Fortaner, S., and Sabbioni, E. (1993). Use of Chelex 100 resin in preconcentration and radiochemical separation neutron activation analysis applied to environmental toxicology and biomedical research. /. Trace Microprobe Tech. 11, 235-250. 

Ion exchange chromatography using Chelex 100 resin has been used for the concentration of rare earth elements from large volumes of seawater, with recoveries of 85-112% [636]. 

A method described by Hirata and Honda [618] uses a flow injection analysis manifold for pH adjustment of a seawater sample, followed by concentration of zinc on a column packed with Chelex 100 resin. The zinc was eluted with nitric acid and determined by atomic absorption spectrometry. The detection limit is 0.5 p,g/l and the relative standard deviation is 2.7% at the 10 ig/l level. 

Olsen et al. [660] used a simple flow injection system, the FIAstar unit, to inject samples of seawater into a flame atomic absorption instrument, allowing the determination of cadmium, lead, copper, and zinc at the parts per million level at a rate of 180-250 samples per hour. Further, online flow injection analysis preconcentration methods were developed using a microcolumn of Chelex 100 resin, allowing the determination of lead at concentrations as low as 10 pg/1, and of cadmium and zinc at 1 pg/1. The sampling rate was between 30 and 60 samples per hour, and the readout was available within 60-100 seconds after sample injection. The sampling frequency depended on the preconcentration required. 

Nygaard et al. [752] compared two methods for the determination of cadmium, lead, and copper in seawater. One method employs anodic stripping voltammetry at controlled pH (8.1,5.3 and 2.0) the other involves sample pretreatment with Chelex 100 resin before ASV analysis. Differences in the results are discussed in terms of the definition of available metal and differences in the analytical methods. 

Greenberg and Kingston [821,822] used a solid Chelex 100 resin to preconcentrate these elements from 100-500 ml of estuarine and seawater prior to their determination. A procedure is described for the preconcentration of 100 ml of estuarine and seawater into a solid sample using Chelex 100 resin. This solid sample weighs less than 0.5 g, and contains the transition metals and many other elements of interest, but is essentially free of alkali metals, alkaline earth metals, and halogens. 

The application of the Chelex 100 resin separation and preconcentration, with the direct use of the resin itself as the final sample for analysis, is an extremely useful technique. The elements demonstrated to be analytically determinable from high salinity waters are cobalt, chromium, copper, iron, manganese, molybdenum, nickel, scandium, thorium, uranium, vanadium, and zinc. The determination of chromium and vanadium by this technique offers significant advantages over methods requiring aqueous final forms, in view of their poor elution reproducibility. The removal of sodium, chloride, and bromide allows the determination of elements with short and intermediate half-lives without radiochemistry, and greatly reduces the radiation dose received by personnel. This procedure was successfully applied in a study of... 

Cadmium Cadmium collected on Chelex-100 resin and elution with Graphite furnace AAS nitric acid [118]... 

Calcium Adsorption on Chelex-100 resin, desorbed with hydrochloric acid Flame photometry at 622 nm [167]... 

Lead Lead pre-concentrated on Chelex-100 resin Inductively coupled plasma 0.6 ng/1 [871,872]... 

Table 5.14. Application of Chelex-100 resin to the pre-concentration of metals in seawater prior to analysis by graphite atomic spectrometry ...

The benefits imparted by preconcentration to improved sensitivity are illustrated in the example of lead preconcentration on Chelex 100 resin [871,872], followed by analysis by ICP-AES. Without preconcentration the best detection bmit achievable is 60 ng/1, via direct nebubsation. When the Chelex 100 preconcentration step is included, the detection limit improves to 0.6 ng/1, i.e., 100 times better, which is a very important improvement achieved in the analysis of seawaters. Examinaton of Table 5.12 reveals that the following metals can be determined with detection limits in the 1 -10 ng/1 range beryllium (0.6 ng/1),... 

Analytical Procedure We followed the OECD guidance document [United Nations 2007, p. 548] for the preparation of a standardized marine test medium. The document states that trace metals should be removed from the test medium before T/D tests are performed. For this step we used a Chelex-100 resin in a column set-up with a flow rate of 5 ml/min. 

Pai SC, Whung PY, Lai RL. Preconcentrahon Efficiency for Chelex-100 Resin for Heavy Metals in Sea Water, parts 1 and 2 Analyhca Chimica Acta 1998 211 257-280. 

ET-AAS with graphite furnace tubes constituted the analytical support for the speciation analysis of Al and the concomitant determination of Al (III) in tea infusions, as described by Alberti and coworkers [141], Lvov platforms incorporated into the graphite furnace atomizers enabled the authors to attain an LoD of 2 xg l-1 Al. The determination was not impaired by the relatively high solid contents. Adsorption of Al on ion Chelex-100 resin was employed to estimate the free metal content and the concentration and stability constants of complexed Al species. The metal is reported to be present in total concentrations from 0.09 to 0.26 mM, but mainly linked to strong complexes. Strong complexation is demonstrated by the inability of Chelex-100 to dissociate the complexes. These results are considered by the authors as an explanation of the low toxicity of the Al associated with tea infusions. The concentration of free Al was found to be very low (at the nM level). No structural or chemical information about the ligands was obtained from the method. 

Manganese as well as other transition metals are separated quantitatively from alkali and alkaline earths elements in sea water with the Chelex-100 resin mentioned in chapters 2.3.3 and 2.3.4. The pH of sea water is adjusted to 5.0-5.5. Alkali and alkaline earth metal ions are eluted from the resin with ammonium acetate whereas manganese is eluted with 2.5 M HN03 65). 

Fig. 4.5.4. An example of separation of uridine, guanosine, cytidine and adenosine by ligand exchange chromatography [151]. Column 33 xO.9 cm, Chelex 100 resin in Cu form, 200-400 mesh, elution with 1 M ammonium hydroxide, flow rate 0.77 ml/min.

Rao, M.G., Grupta, A.K., Williams, E.S. and Aguwa. A.A. (1982). Sorption of Heavy Metal Ions on Chelex-100 Resin. AlChE Symposium series, 103. 

Because of the extremely low concentrations of the trace metals in seawater, some method of concentration is commonly employed. Adsorption on Chelex 100 resin, chelation followed by extraction with an organic solvent, or co-precipitation, are techniques favored [98-100]. Intercomparison of concentration methods demonstrates that the choice of method depends on the metal chosen for analysis no collection method appears to be clearly the best for all metals. 

The relative merits of ion-exchange and reversed phase modes are discussed in a study of the nucleotide pools from mammalian tissues (Brown et al., 1982). The tissue extracts were initially purified on a Cu -loaded Chelex 100 resin to maximise both resolution and sensitivity during the main HPLC separations. It was concluded that the best routine method was on the anion-exchange column containing jaBondapak NH2 (Fig. 11.1.7), but where necessary this could be complemented with reversed phase or reversed phase ion-pair HPLC. 

Greenberg et al. [86] employed a preirradiation chemical separation involving retention of the vanadium moiety on Chelex-100 resin. Tlie vanadium recovery was 97.6 3%. These authors report a vanadium value of 0.055 0.035 ng/g for bovine semm SRM 1598 and a value of 0.028 0.02 ng/g for random samples of human blood serum. While these values are more in line with those of Versieck et al. in different serum matrices ( l ng), there remains the question of how meaningful are quoted values less than 1 ng for physiological interpretation in clinical chemistry. We conclude, based on serum values from different laboratories, that the vanadium concentration in serum is s 1 ppb. 

FIA system for the extraction of metals by use of a column packed with Chelex 100 resin. IV Injection valve. 

Add 5 grams of Chelex 100 Resin to 100 ml of sterile, distilled water. Store in the refrigerator, discard If you see growth or contamination... 

Figure 7. Conq>arison of the catalytic activity of transition metal texaphyrins in effecting the air-based oxidation of ascorbic acid in buffered aqueous media. Conditions [Ascorbate] - 1.23 mM sidfstrate catalyst ratio = 20 1 pH 7.5 HEPES/NaCl buffer solution pretreated with Chelex 100 resin ambient...

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