Table 3. Hg(II) Ion Determination in Water Samples by Using Surface-Enhanced Raman Scattering Signal.
| probe/sensor fundamentals | calibration grapha | LR (μg L–1) | LOD (μg L–1) | samples/evaluated CHg(II) | ref |
|---|---|---|---|---|---|
| Through the strong mercury and sulfur bond, Hg(II) ion prevents the adsorption of MESNA on the surface of AgNPs resulting in a decrease of SERS of the MESNA modified AgNPs. | ΔI795 vs CHg(II) | 2–400 | 0.48b | Water samples of two different lakes and groundwater samples were spiked with 40 and 240 μg L–1 Hg(II) ion. | (56) |
| Hg(II) ion interacts with IP6 stabilized AuNPs modified by CV and TC, decreasing the intensity of SERS band of the probe at 1173 cm–1 due to the CV molecules detachment from the surface. | I1173/I0 vs CHg(II) | 0.1–1 | 1 × 10–4 | Five tap and five river water samples were spiked with 0.4 μg L–1 Hg(II) ion. | (57) |
| Hg(II) ion changes the SERS signal of DNA modified AuNPs and 4-nitrothiophenol system, through the transformation of ssDNA into double helical DNA by T–Hg2+–T interaction. Au nanochains length grew longer with increasing the CHg(II) ion, and the increase of SERS signal is detected. | I1344 vs CHg(II) | 0.001–0.5 | (4.5 × 10–4)b | Three drinking water samples were spiked with 0.04; 0.08 and 0.15 μg L–1 Hg(II) ion. | (58) |
| Nanostructured gold substrate functionalized with a crown ether formed by ADB18C6 and MPA as SERS reporter is employed. The binding of Hg(II) ion into the crown ether layer cavity increases the intensity of Raman band at 1501 cm–1. | I1501 vs log CHg(II) | 0.002–200 | (1.02 × 10–4)b | One tap water sample was spiked with 5 μg L–1 Hg(II) ion. | (59) |
| Surface modified AuNRAs with 4-MPBA as SERS reporter are employed. In the presence of Hg(II) ion spectral changes of reporter including the disappearance, emergence, and shift of Raman peaks are detected. | log I vs –log CHg(II) | 0.02–2000 | ca. 0.02 by visual inspection | One lake water sample and one groundwater sample, each spiked with 2 μg L–1 Hg(II) ion. AFS was applied for results comparison. | (60) |
| I measured at 467, 1048, 1085, and 1536 cm–1 | |||||
| Hg(II) ion interacts with surface-stabilized HEPES-AuNSs on a paper substrate forming a AuHg amalgam. The substrate is incubated in a HAuCl4, HCl and H2O2 solution with 4-MBA (reporter). SERS bands decrease as the CHg(II) increases. | peak area (1590)vs −log CHg(II) | 0.02–200 | 0.006b | Three seawater samples and three pond water samples, each spiked with 0.2; 2 and 20 μg L–1 Hg(II) ion. | (61) |
| 0.066 (seawater)b | |||||
| 0.046 (pond water)b | |||||
| A chip formed by AuNPs immobilized on aminopropyl trimethoxysilane modified ITO surface and assembled GSH molecules was constructed, and 4-Mpy was used as SERS reporter. The interaction of Hg(II) ion with the chip GSH molecules and 4-Mpy increases the intensity of SERS peaks of 4-Mpy. CHg(II) is measured through the 1093 cm–1 band intensity. | ΔI1093 cm–1 vs –log CHg(II) | 0.002–200 | 1.76 × 10–3 | Five seawater samples were filtered through filter paper and 0.22 μm microporous filters. Samples were spiked with 0; 0.002; 0.02; 0.2 and 2 μg L–1 Hg(II) ion. Samples with 0.2 and 2 μg L–1 Hg(II) also were investigated with ICP-MS. | (62) |
Subscript for I is the wavelength in cm–1.
LOD = 3Sb/m, where Sb is the standard deviation of the blank signal and m is the slope of calibration line. Abbreviations: A, absorbance; ADB18C6, aminodibenzo-18-crown-6 derivative; AFS, atomic fluorescence spectrometry; AgNPs, silver nanoparticles; AuNPs, gold nanoparticles; AuNRAs, Au nanorod arrays; AuNSs, gold nanostars; CHg(II), concentration of Hg(II) ion; CV, violet crystal; GSH, glutathione; HEPES, 2-[4-(2-hydroxyethel) piperazine-1-yl]ethanesulfonic acid; I, intensity; ICP–MS, inductively coupled plasma mass spectrometry; IP6, inositol hexaphosphate; ITO, indium tin oxide; LOD, limit of detection; LR, linear range; MPA, mercaptopropionic acid; 4-MBA, 4-mercaptobenzonic acid; MESNA, sodium 2-mercaptoethanesulfonate; 4-MPBA, 4-mercaptophenylboronic acid; 4-Mpy, 4-mercaptopyridine; NIR, near-infrared; NPs, nanoparticles; SERS, surface-enhanced Raman scattering; ssDNA, single-stranded DNA; T, thymine; TC, trisodium citrate; TMB, 3,3′,5,5′-tetramethylbenzidine.