Table 1.
Summarized results of the formation and stoichiometry of isoquercitrin complexes with iron and copper at all pH values analyzed.
| pH 4.5 | pH 5.5 | pH 6.8 | pH 7.5 | ||
|---|---|---|---|---|---|
| Job’s method | 1:1 | 1:1 | 1:1 | 1:1 | |
| Fe3+ | Complementary approach | 1:1 | 1:1 | 1:1 | 1:1 |
| Competitive method | low affinity | X | X | X | |
| Job’s method | no complex | low affinity | 1:1 | 1:1 | |
| Fe2+ | Complementary approach | no complex | low affinity | 1:1 → 3:2 | 1:1 |
| Competitive method | low affinity | low affinity | 2:1 | 3:2 | |
| Job’s method | no complex | 1:1 or 3:2 | 1:1 | 1:1 | |
| Cu2+ | Complementary approach | no complex | 1:1 | 1:1 | 1:1 |
| Competitive method | X | low affinity | 2:1 | 2:1 * | |
| Job’s method | no complex | ||||
| Cu+ | Complementary approach | no complex | |||
| Competitive method | low affinity | ||||
The data are shown as a ratio of isoquercitrin to metal. Low affinity—the complex was detected but due to low affinity of isoquercitrin toward the metal, the stoichiometry cannot be determined; *—unstable; X—method cannot be applied.