Fast technetium Eigen-colloid determination: preparative CPC combined with suspension liquid scintillation

Full text of publication follows: Both medical and environmental studies concerned with the solubility and the complexation chemistry of technetium have encountered colloidal Tc(IV)-forms. Although the existence of the Tc colloids has been proven by various techniques [1-6], their determination still remains an issue. Recently a Column Precipitation Chromatography (CPC) technique was developed which enabled the quantitative determination of technetium Eigen-colloids. Based on this technique, a solid phase extraction (SPE)-like methodology was developed that can be used in combination with suspension liquid scintillation to provide a fast analysis of the Eigen-colloid content of a sample. The CPC technique is a thorough analysis methodology for the quantitative determination of the Eigen-colloid content of a sample containing reduced technetium species. This technique requires a relative long elution scheme and fractionation of the eluate. The fractionation also implies a relatively long counting time to determine the Eigen-colloid activity of a sample. Currently an SPE-like analysis methodology was developed which combines a good estimate of the Eigen-colloid content with fast analysis times. To construct a methodology providing both features a specialized extraction apparatus was constructed and a quantitative suspension liquid scintillation technique was developed. This combination enables the Eigen-colloid determination within a short experimental time (15 min) and a limited counting time (60 min). The authors acknowledge a grant from KULeuven University and financial support from the KULeuven Geconcerteerde Onderzoeksacties (GOA2000/007). We also kindly acknowledge NIRAS/ONDRAF for financial support from Contract CCHO 20004004862 [1] Grossmann, B. and R. Muenze, Relationship between complex formation by 99Tc(IV) and the chemical structure of aliphatic carboxylic acid ligands. The International Journal of Applied Radiation and Isotopes, 1982. 33(3): p. 189-192. [2] Mang'era, K., et al., Synthesis and evaluation of the 99mTc-complexes of -cysteine acetyl-di-glycine (a hybrid of MAG3 and -EC) and of -[beta]-homocysteine acetyl-di-glycine. Nuclear Medicine and Biology, 2000. 27(8): p. 781-789. [3] Sekine, T., et al., Radiolytic formation of Tc(IV) oxide colloids. Radiochimica Acta, 2002. 90(9- 11): p. 611-616. [4] Maes, A., et al., Evidence for the Formation of Technetium Colloids in Humic Substances by X-Ray Absorption Spectroscopy. Environmental Science and Technology, 2004. 38(7): p. 2044-2051. [5] Ben Said, K., et al., Gamma radiation effects on potassium pertechnetate in carbonate media. Applied Radiation and Isotopes, 2001. 54(1): p. 45-51. [6] Vichot, L., et al., XAS study of technetium(IV) polymer formation in mixed sulphate/chloride media. Radiochimica Acta, 2002. 90(9-11): p. 575-579. (authors)