Rapid and selective RRS determination of ferrocyanide with a nanogold surface molecularly imprinted polymethacrylic acid probe†

In this work, a nanogold surface molecularly imprinted polymer spectral probe (AuNP@MIP) for selectively identifying ferrocyanide was prepared under microwave irradiation using nanogold as the core, ferrocyanide as the template ion, methacrylic acid as the monomer, and ethylene glycol dimethacrylate as the cross-linking agent. AuNP@MIP was found to produce a resonance Rayleigh scattering (RRS) peak at 370 nm. When potassium ferrocyanide (K₄Fe(CN)₆) was present, a AuNP@MIP–Fe(CN)₆ complex was formed, producing RRS-energy transfer (RRS-ET). With an increase in ferrocyanide concentration within a certain range, the RRS intensity at 370 nm decreased linearly, and the detection range was 0.02–0.40 μmol L⁻¹, with a detection limit as low as 0.006 μmol L⁻¹ ferrocyanide. This new method has the advantages of simplicity, rapidity, and selectivity when applied for the determination of K₄Fe(CN)₆ in table salt.