1988 Volume 4 Issue 2 Pages 175-179
Acceleration effects of organic ligands for the metal ion exchange reaction of cadmium(II) with 5, 10, 15, 20-tetrakis-(N-methyl-4-pyridinio)porphinatolead(II) (Pb(II)-tmpyp) have been studied. Among 20 kinds of organic ligands, L-tryptophan showed the highest efficiency as an accelerator. In the presence of 2×10-4M of L-tryptophan, Cd(II)-tmpyp complex was formed within 2s at 20°C, over the pH range of 9.5-11.5. Based on this finding, a rapid and highly sensitive stopped-flow spectrophotometric method for trace amounts of cadmium(II) was developed. The apparent molar absorptivity at 448.0nm was 1.68×105M-1 cm-1and the relative standard deviation was 2.33% for 1.17μg of cadmium (6 determinations). The determination limit was at 23.3ng (4.16×10-9M) of cadmium(II). Tolerance limits of 18 kinds of metal ions were discussed.