Electrocatalytic detection of phenolic estrogenic compounds at NiTPPS|carbon nanotube composite electrodes

A Ni(II)tetrakis(4-sulfonatophenyl) porphyrin (NiTPPS)|carbon nanotube composite electrode that shows strong catalytic and antifouling capability was developed to detect a series of phenolic endocrine compounds including bisphenol A, nonylphenol and ethynylestradiol. This electrode was fabricated by electropolymerizing NiTPPS complexes on a carbon nanotube-modified glassy carbon electrode. Optimized experimental parameters including a hydrodynamic potential of 0.7 V for flow injection analysis (FIA) and a NiTPPS surface coverage of 2.2 nmol cm−2 (standard deviation 0.2 nmol cm−2; n = 6) were obtained for detection of the endocrine disrupting compounds. The sensor responded well to all the tested compounds with limits of detection ranging from 15 nmol L−1 to 260 nmol L−1 (based on three times S/N ratio) under FIA conditions. Both carbon nanotubes and NiTPPS account for the excellent performance of the composite modified electrode.