Photooxidation assisted sensitive detection of trace Mn2+ in tea by NH2-MIL-125 (Ti) modified carbon paste electrode

Abstract NH 2 -MIL-125(Ti), as a highly porous titanium-based MOF, has been firstly reported to show an efficient photooxidation activity toward Mn 2+ in pH 8.5 NH 3 –NH 4 Cl (0.04 M) buffer under visible light. Mn 2+ was detected quantitatively by cathodic stripping voltammetric method based on the oxidized manganese product. The stripping peak currents on NH 2 -MIL-125(Ti)/CPE was linearly proportional to the concentration of Mn 2+ in the range from 1.0 × 10 −8 to 1.0 × 10 −5  M with the detection limit of 4.0 × 10 −9  M. This method has been successfully applied for the detection of Mn 2+ in tea samples, and the results were in close agreements with those obtained by atomic absorption spectroscopic method.