Zr-based metalloporphyrin MOF probe for electrochemical detection of parathion-methyl

An electrochemical (EC) sensor based on metalloporphyrin metal-organic framework (MOF) for the detection of parathion-methyl (PM) has been developed. The prepared MOF-525(Fe) exhibits great signal enhancement toward the electrochemical detection of PM owing to its unique structural properties and electrochemical activities. Under optimal experimental conditions, the as-prepared MOF-525(Fe) based EC sensor exhibited excellent PM sensing performance with a wide linear detection range (0.1 μM-100 μM) and low limit of detection (LOD, 1.4 nM). Compared to its corresponding Fe metalloporphyrin (linker), MOF-525(Fe) exhibited a superior sensitivity (28.31 μA cm^-2·μM^-1), which is 3.7 times higher than the sensitivity of FeTCPP linker (7.56 μA cm^-2·μM^-1) towards PM. The improved performance is associated with the high specific surface area and the large pore channels of MOF-525(Fe) facilitating a better interaction between PM and the Fe metalloporphyrin active sites, especially in the lower concentration range. Moreover, a possible affinity of the PM molecules toward Zr₆ clusters may also contribute to the selective enrichment of PM on MOF-525(Fe). This EC sensor further demonstrated high selectivity in the presence of interfering molecules. The recovery results further confirm accurate PM sensing in actual samples, which suggests promising applications for the rapid detection of environmental organophosphates by metalloporphyrin MOFs.