Table 3: Comparison of the proposed optode with other spectrophotometric methods for determination of Hf(IV).
| Reagent | pH | λmax (nm) |
Range (μg cm−3) |
DL (μg cm−3) |
RSD (%) |
ε L mol−1 (cm−1 × 104) |
S.S. (ng cm−2) |
Ref. |
| 1-(2-Pyridylazo)-2-naphthol | 4.0 | 545 | 0.2–3.6 | 0.06 | 2.7 | 3.86 | 0.0046 | [19] |
| 2-Amino-3-(4-bromophenyl-azo)-8,9- dihydro-7H-pyrazolo [1,5-a]quinazolin-6-one |
3.2–4.7 | 368 | 0.005–1.0 | 0.013 | 2.4 | 25.1 | 0.0032 | [12] |
| Ficus carica tree leaves | 6.0 M HCl | 421 | 2.0–11 | 0.312 | 3.4 | 0.28 | 0.0038 | [42] |
| Arsenazo III | 9.0 M HCl | 520 | 0.0–20 | 0.3 | 2.4 | 1.36 | 0.0023 | [43] |
| 1-(2-Thiazolylazo)-2-naphthol | 2.5 | 590 | 0.0–9.0 | — | 2.9 | 3.97 | 0.0056 | [44] |
| BTABPD | 5.0 | 616 | 5.0–185 (ng cm−3) |
1.58 (ng cm−3) |
1.85 | 836 | 0.00021 | P.M. |
| S.S: Sandell sensitivity. P.M: Proposed methods. | ||||||||