[en] To establish an excretion technique of RI metals (⁶³Ni, ¹⁰⁹Cd and ²¹⁰Pb) in vivo, many kinds of complexing agents were developed. The performance evaluation of these agents was carried out by mouse in vivo. They are various kinds of carbohydrate formazan derivatives with deduced uni-saccharide (D-glucose, D-mannose and D-galactose) or disaccharide (maltose) and functional group (-COOH, -NH, -OH, -N=N- and pyridyl group). For example of synthesis method of, formazan derivative with maltose was described. 100 mouse with 8 to 10 g were classified to four groups. 1 group get 0.1 ml of nickel ion hemoperitoneum injection once (control). 2 group had 0.1 ml nickel ion hemoperitoneum injection at one time a day and then 0.1 ml eccritic hypodermic injection during 5 days. 3 group get 0.1 ml cadmium ion hemoperitoneum injection once (control). 4 group had 0.1 ml cadmium ion hemoperitoneum injection and then 0.1 ml eccritic hypodermic injection at one time a day for 5 days. Decay of residue was measured. PCF-maltose showed the best chemical protector against radiation in these agents. Especially, this eccritic can excrete ⁶³Ni and ¹⁰⁹Cd without effect on the essential metals such as calcium, magnesium and iron. (S.Y.)