Chelex^® 100 Resin

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Overview

Analytical Grade Resin Selection Guide

Change in Structure

Change in Structure of Chelex Resin with Increasing pH

Chelex chelating resin is efficiently regenerated in dilute acid and operates in basic, neutral, and weakly acidic solutions of pH 4 or higher. At very low pH, the resin acts as an anion exchanger. This figure shows the zwitterionic forms of the Chelex resin as a function of pH.

Selectivity for Divalent Cations

Hg⁺²	1060	Fe⁺²	0.130
Cu⁺²	126	Mn⁺²	0.024
UO⁺²	5.70	Ba⁺²	0.016
Ni⁺²	4.40	Ca⁺²	0.013
Pb⁺²	3.88	Sr⁺²	0.013
Zn⁺²	1.00	Mg⁺²	0.009
Co⁺²	0.615	Na⁺¹	0.0000001
Cd⁺²	0.390

The selectivity of Chelex resin for metal cations corresponds to that of iminodiacetic acid. This is a list of selectivity factors for several divalent cations. The selectivity factor is a quantitative measure of the affinity that Chelex resin displays for a particular cation compared to its affinity for a reference cation, in this case Zn+2.

Sample Applications and References

Chelex 100 Sample Applications and Resins

Application	Reference

Preparation of metal-free apoenzyme	O'Keefe, E. T., Hill, R. L. and Bell, J. E., Biochem., 19, 4954 (1980).
Removal of calcium from sarcoplasmic reticulum vesicles	Chiesi, M. and Inesi, G., Biochem. 19, 2912 (1980).
Removal of extraneously bound metal ions from enzymes prior to NMR and ESR studies	Barker, R., et al., Biochem. J., 177, 289 (1979).
Batch removal of calcium from whole blood	Raymond, F A. and Weinshilboum, R. M., Clin. Chim. Acta, 58, 185 (1975).
Removal of metals from ATP	Sontheimer, G. M., et al., Biochem., 26, 2701 (1987).
Removal of metals from buffer, brine, and biological solutions	Knapp, G., et al., J. Anal. Atomic Spectrometry, 2, 611 (1987); Laue, T. M., et al., Biochem., 28, 4762 (1989).
Removal of metals from S100b and melittin	Baudier, J., et al., Biochem., 26, 2886 (1987).
Purification of dinucleotides	Reinhardt, C. G. and Krugh, T. R., Biochem., 17, 4845 (1978).
Removal of metals from cell suspension	Bosron, W. F., Kennedy F. S. and Vallee, B. L., Biochem., 14, 2275 (1975).
Batch removal of metals from urine	Agarwal, M., Bennett, R. B., Stump, I. G. and D'Avria, J. M., Anal. Chem., 47, 924 (1975).
Removal of metals from enzyme solutions	Dunn, M. F., Pattison, S. E., Storm, M. C. and Quiel, E., Biochem., 19, 718 (1980).
Removal of metals from guinea pig complement	Amiraian, K., McKinney, J. A. and Duchna, L., Immunology, 26, 1135 (1974).
Removal of aldehydes and peroxides from polyethylene glycol	Ray, W. J. and Pavathingal, J. M., Anal. Biochem., 146, 307 (1985).
Removal of interfering components from myo-inositol	Brandt, S. J., Dougherty, R. W., Lapetina, E . G. and Niedel, J. E., Proc. Nat. Acad. Sci., 82, 3277 (1985).
Calcium removal from protein kinases	Putnam-Evans, C. L., Harmon, A. C. and Cormier, M. J., Biochem., 29, 2488 (1990).
Removal of divalent cations from NMR stock solutions	Devlin, C. C. and Grisham, C. M., Biochem., 29, 6192 (1990). Chuknyisky, P. P., Rifkind, J. M., Tarien, E., Beal, R. B. and Eichhorn, G. L., Biochem., 29, 5987 (1990).
Removal of paramagnetic impurities from oligonucleotides for NMR analysis	Kochoyan, M., Leroy, J.L. and Guéron, M. Biochem., 29, 4799 (1990), Schroeder, S.A., Roongta, V., Fu J. M., Jones, C.R., and Gorenstein, D.G., Biochem., 28, 8292 (1989).
Trace metal removal from buffer solutions and seawater	Pai, S.-C., Chen, T.-C., Wong, G.T.F. and Hung, C.- C., Anal. Chem., 62, 774 (1990)
Iron removal from bacteria	Trost, J.T. and Blankenship, R.E., Biochem., 28, 9898 (1989)
Trace metal ion removal from buffer solutions	Yong, G., Leone,C. and Strothkamp, K.G., Biochem., 29, 9684 (1990). Severns, J.C. and McMillin, D.R., Biochem., 29, 8592 (1990) Shang, S., Liao Y.-D., Wu, F., Y,-H. and Wu, C.- W., Biochem., 28, 9790 (1989), Chung, H.K. and Ingle, J.D., Anal. Chem., 62, 2547 (1990), Grimshaw, C.E., Shahbaz, M. and Putney, C.G., Biochem., 29, 9936 (1990).
Removal or multivalent cation contaminants	Swanson, J.E., and Feigenson, G.W., Biochem., 29, 8291 (1990).
Purification of NMR reagents	Brito, R.M.M., Rudolph, F.B., and Rosevear, P.R., Biochem., 30, 1461 (1991). Ray, W.J. Burgner, J.W., and Post, C.B., Biochem., 29, 2770 (1990)
Calcium removal from calmodulin	Vorherr., T., James, P., Krebs, J., Enyedi, A., McCormick, D.J., Penniston, J.T., and Carafoli, E., Biochem., 29, 355 (1990)
Purification of zinc isotopes from human blood and excrement	Gökmen, I.G., Aras, N.K., Gordon, G.E., Wastney, M.E., and Henkin, R.I., Anal. Chem., 61, 2757 (1989)
Calcium removal from buffer solutions	Kinoshita, C.M., Ying, S.-C., Hugli, T.E., Siegel, J.N., Potempa., L.A., Jiang, H., Houghten, R.A. and Gewurz, H., Biochem., 28, 9840 (1989), Thielens, N.M., Dorsselaer, A.V., Gagnon, J. and Arlaud, G.J., Biochem., 29, 3570 (1990)
Removal of zinc from buffer solutions	Jefferson, J.R., Hunt, J.B., and Ginsburg, A., Biochem., 29, 6687 (1990)
DNA Extraction for PCR	Walsh, P.S., Metzger, D.A. and Higuchi, R., BioTechniques, 10, 506 (1991)

Stability of AG Resins

Stability of Selected Analytical Grade Resins to Various Treatments


Resin	Heat*	Solvents (Alcohols, Hydrocarbons, etc.)	Oxidation	Reduction

AG 1	OH- form, fair to 50°C Cl- and other forms, good to 150°C	Very good	Slowly dissolves in hot 15% HNO₃ or concentrated H₂O₂	Good**
AG 2	OH- form, fair to 30°C Cl- form, good to 150°C	Very good	Slowly dissolves in hot 15% HNO₃	Good**
AG 50W	Good to 150°C	Very good	Slowly dissolves in hot 15% HNO₃	Very good
AG 4-X4	Good to 60°C	Good	Good	Unknown
AG 501-X8	Good to 50°C	Very good	Slowly dissolves in hot 15% HNO₃ or concentrated H2O₂	Good**
AG 11 A8	Good to 100°C	Good	Slowly dissolves in hot 15% HNO₃ or concentrated H2O₂	Good
Bio-Rex 5	Good to 60°C	Good	Good	Excellent
Bio-Rex 70	Good to 100°C	Good	Good	Good
Bio-Rex MSZ 501(D)	Good to 50°C	Very good	Slowly dissolves in hot 15% HNO₃ or concentrated H₂O₂	Good**
Chelex 100	Good to 75°C	Good	Breaks down in strong oxidizing agents	Unknown

* All anion resins may be autoclaved except the CH- form; all cation exchange resins may be autoclaved.
** AG 1, AG 2, AG 501, and Bio-Rex MSZ 501 (D) resins will slowly break down in the presence of sulfur-containing reducing agents.

AG Resin Wet Mesh and Diameters

Wet mesh (U.S. Standards)	16	20	40	50	80	100	140	200	270	325	400
Diameter, µm	1,180	850	425	300	180	150	106	75	53	45	38

Chelex 100 resin is a styrene divinylbenzene copolymer containing paired iminodiacetate ions, which act as chelating groups in binding polyvalent metal ions. The carboxylic acid groups of Chelex 100 resin classify it as a weak cation exchange resin, but it differs from other exchangers in this class by featuring uniquely high selectivities for metal ions and much higher bond strengths. The resin can be used to ultrapurify buffers and ionic reagents: it will scavenge metal contaminants without altering the concentration of nonmetal ions.

Chelex 100 chelating ion exchange resin has a stronger selectivity for copper, iron, and other heavy metal ions over monovalent cations such as sodium and potassium. Its selectivity for divalent over monovalent ions is approximately 5,000 to 1, and it has a strong attraction for transition metals, even in highly concentrated salt solutions.

The following forms of Chelex 100 resin are available:

Analytical grade Chelex 100 resin — exhaustively sized, purified, and converted to make it suitable for accurate, reproducible analytical techniques
Biotechnology grade Chelex 100 resin — the analytical grade form certified to contain fewer than 100 microorganisms per gram of resin

Larger volumes and special packaging for industrial applications are available upon request.

Type	Weak cation, chelating
Functional group	R-CH₂N(CH₂COO^-)₂
Matrix	Styrene divinylbenzene
Crosslinkage	1%
Approx. MW exclusion	3,500
Operating stability/pH range	4–14/0–14
Min. wet capacity (meq.ml)	.04
Nominal density	0.65
Ionic forms	Sodium, iron*
* Iron form is glyphosate concentration.