Table 2.
The metrological characteristics of the developed tests for Co(II), Rh(III), and Pd(II).
| Impurity | Analytical reaction/test tool/ | Indication way | Concentration range, mg L−1 | LOD or LOQ, mg L−1 |
RSD in decimal fraction (for median range) |
|---|---|---|---|---|---|
| Co(II) | Indigocarmine oxidation by H2O2
in the presence of Co(II)/sandwich/ |
Visual | 0.5–10 | 0.5∗ | — |
| Pyrocathechin oxidation in the presence of Co(II)/sandwich/ |
Visual | 0.01–1.0 | 0.01∗ | — | |
| Instrumental (RGB) | 0.005–0.1 | 0.005∗∗
6σ |
0.06 | ||
| Instrumental (square of the spot) |
0.01–1.0 | 0.01∗∗
the first point |
0.12 | ||
| Formation of color complex with PAN/paper/ | Visual | 0.25–10 | 0.25∗; 0.25∗∗ the first point |
— | |
| 0.002–0.1 (preconcentration) |
0.002∗∗
(preconcentration) |
||||
| Instrumental | 0.1–10; 0.001–0.1 (preconcentration) |
0.05∗∗
6σ; 0.001∗∗ (preconcentration) the first point |
0.05 | ||
| Formation of color complex with thiocyanate/PUF/ | Visual | 0.1–1.5 | 0.02∗ | — | |
| Instrumental | 0.01–1.5 | 0.01∗∗
RSD = 0.3 |
0.01 | ||
|
| |||||
| Rh(III) | Oxidation of Cu(II) by periodate in the presence of Co(II)/blisters/ |
Visual | 0.01–0.8 | 0.005∗ | — |
| Instrumental | 0.01–0.8 | 0.005∗∗
6σ; 0.01∗∗ RSD = 0.3, the first point |
0.1 | ||
|
| |||||
| Pd(II) | Formation of color complex with rhodamine 6G/PUF/ | Visual | 0.04–0.8 | 0.04∗ | — |
| Instrumental | 0.04–0.8 | 0.06∗∗
6σ; 0.08∗∗ RSD = 0.3, 0.04∗∗ the first point |
0.1 | ||
| Visual, instrumental | 0.004–0.08 (preconcentration) |
0.004∗∗
(preconcentration) the first point; 0.008∗∗ (preconcentration) RSD = 0.3 |
0.1 | ||
Sample volume n = 10; ∗LOD; ∗∗LOQ.