A new CaMOF resonance Rayleigh scattering probe for trace sulfide based-methylene blue receptor

The as-preared Ca metal organic framework (CaMOF) nanosol exhibits a strong resonance Rayleigh scattering (RRS) peak at 380 nm under the chosen conditions. The S2− reacts with p-aminodimethylaniline (DMPD) to produce methylene blue (MB) in the presence of Fe(III). The produced MB acts as a RRS receptor and CaMOF as RRS donor, the both taken place RRS-energy transfer (RRS-ET) when MB was adsorbed on the CaMOF surface to result in the RRS signal quenching. As the concentration of Na2S increasing, the MB formed increased and the RRS-ET enhanced, leading to a linear decreasing in the RRS intensity at 380 nm. The decreased value ΔI shows a good linear relationship with the concentration of Na2S in the range of 0.050–5.0 μmol/L. Accordingly, a new RRS-ET method was established to determine sulfate in water and H2S in air samples, with high sensitivity, good selectivity and simplicity.