... radionuclides,principally129I (Muramatsu and Yoshida, 1995; Parry et al., 1995),232Th and 2 38 U (Edgington, 1967; Fakhi et al., 1 988 ), and 237Np (Ruf and Friedrich, 19 78; Byrne, 1 986 ; May and Pinte, 1 986 ). For the metal ... theresidual sample is dissolved in 8 M HNO3 and passed through a Sr. Specextraction chromatography column. This consists of 4,40(50)-bis-t-butyl-cyclohexano- 1 8- crown-6, a highly selective complexant ... long-lived isotopes (Landrum et al., 1969; Efurdet al., 1 986 ; Taylor et al., 19 98; Goodall and Lythgoe, 1999). In terms ofultimate sensitivity, counting techniques are usually better than ICP-MS.This...