A facile COF loaded-molybdate resonance Rayleigh scattering and fluorescence dimode probe for determination of trace PO43−

A new covalent organic framework loaded-molybdate (COFMo) nanomaterial was prepared simply by solvothermal procedure and characterized by electron microscopy and molecular spectral techniques. The COFMo had a strong resonance Rayleigh scattering (RRS) signal at 465 nm and a fluorescence peak at 345 nm. When the PO43- was added in the system, it reacted with the molybdate, which loaded on the surface of COF particles, to form stable phosphomolybdic acid occurring RRS/fluorescence-energy transfer, the RRS and fluorescence signals were decreased. The decreased RRS/fluorescence intensities were linear to the PO43- concentration in the range of 0.053-3.2 nmol/L and 0.10-3.2 nmol/L, with a detection limit of 0.050 nmol/L and 0.090 nmol/L respectively. Accordingly, a new and facile RRS/fluorescence dimode method for detection of trace PO43- was established, only one fluorometer was used.