In H2SO4 solution, the arsenic was reduced to arsine (AsH3) by NaBH4, and absorbed by solution of H3PO4-HAuCl4-NH4SCN-gum arabic. The Au3+ was reduced to nanogold, which led to the absorption value at 555nm increased. Under the selected conditions, the value was linear to the concentration of As (III) in the range of 0.07-1.10 μg/mL, a detection limit of 0.03 μg/mL. The proposed method was applied to detect As (III) in water samples, with satisfactory results.
Nanogolds (AuNPs) were synthesized with the citrate reduction of HAuCl4. In pH 3.0 glycineHCl buffer solution (0.20 mol/L), AuNPs do not aggregate. In the presence of Cr (III), that Cr (III) could form astable Cr (III) citrate complex with the citrate on surface of AuNP in 1: 2 binding stoichiometry, and the AuNPs were aggregated to big AuNPs clusters that led to the resonance Rayleigh scattering (RRS) peak at 530 nm increased greatly. Under the selected conditions, the increased RRS intensity (ΔI530nm) is linear to Cr (III) concentration in the range of 0.25-5.0 μmol/L. This RRS method was applied to determination of Cr (III) in synthetic samples, with satisfactory results. Cr (VI) was also detected after reduction to Cr (III).
In HCl medium and in the presence of CuSO4, Na3AsO4 can be reduced by NaH2PO2 to form As nanoparticles (AsNs) which exhibited a strong resonance Rayleigh scattering (RRS) peak at 370 nm. Under the chosen conditions, the increased intensity at 370 nm was linear to As5+ concentration in the range of 0.48-38.0×10-6 mol/L, with a regression equation of ΔI370nm = 82.3 CAs + 33.9, a correlation coefficient of 0.9878 and a detection limit of 2.0×10-7 mol/L As5+. The proposed method was applied to detect As5+ concentration in waste water, with simplicity, rapidity and accuracy. Thus, a novel RRS spectral method was established to determine As5+.
In pH 6.6 Na2HPO4-citric acid buffer solution and in the presence of KCl, the nanosilver-labeled rabbit anti-hCG (Ag-RAhCG) was aggregated un-specifically to the aggregations. Upon addition of rhodamine 6G (RhG) molecular probe, it adsorb on the surface of Ag-RAhCG aggregations that exhibited the strongest surface-enhnaced resonance Raman scattering (SERRS) peak at 613 cm-1. In the optimal condition, the decreased SERRS intensity responds linearly with the concentration of hCG over 0.05-1.75 µg/mL. Based on this, a new and simple SERRS method has been proposed for the determination of hCG in serum samples, with satisfactory results.
There are strong forces between phenylenediamine (PPD) and nanogold particle (AuNP) that make the AuNPs aggregation and exhibit a strong resonance Rayleigh scattering (RRS) peak at 368 nm. When there is NO2-, it reacts with PPD to generate an azo compound. However, there is weak force between AuNP and the azo compound that can’t make the AuNPs aggregation. When concentration of NO2- increased, the AuNP aggregations become weak that led the RRS peak to decrease. The decreased RRS intensity is linear to NO2-concentration in the range of 1-25 μmol/L. This method was applied to analysis of water samples with simplicity.
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