No abstract

No abstract

No abstract

A novel nickel phthalocyanine/iron oxide nanoparticle (NiTsPc/ION) nanocomposite electrode is proposed for the voltammetric detection of ethinyl estradiol. The method shows a wide linear range (0.07–30 μmol L−1, R2 >0.99), sensitivity of 0.308 μA cm−2/μmol L−1 and limit of detection of 7.8 nmol L−1 (3.3 Sb/b). Recoveries are above 95 % for quantification in tap and treatment plant water samples and synthetic urine. A single electrode can be used in seven consecutive runs (RSD=2.85 %) and responses of different electrodes vary only 7–9 %. The excellent sensing performance of the proposed sensor is ascribed to its porous morphology and efficient charge‐transfer between ION and NiTsPc.

Indium-doped tin oxide (ITO) substrates were surface-modified with layer-by-layer nanocomposite films of anionic nickel(II) tetrasulfonated phthalocyanine (NiTsPc) and positively charged iron oxide nanoparticles (IONs) aiming at the electrocatalytic oxidation of ethinyl estradiol (EE2). Atomic force microscopy and UV−vis and Raman spectroscopies suggest that the successive deposition of NiTsPc/ION bilayers forms a porous supramolecular structure driven by both electrostatic interaction and covalent Fe(III)−O−Ni(II) bridges. Cyclic and differential pulse voltammetry show that EE2 is effectively oxidized at the ITO/ (NiTsPc/ION) electrode while displaying an isolated and welldefined peak at +0.73 V (vs Ag/AgCl). Conversely, bare ITO and ITO modified by either ION or NiTsPc alone are unable to oxidize EE2. The benefit of the NiTsPc/ION bilayers for the EE2 oxidation is assigned to the charge-transfer process occurring between IONs and NiTsPc through the Fe(III)−O−Ni(II) bridge. This process suppresses the oxidation of both the phthalocyanine ring and Ni(II), which appear in the same potential range of EE2 oxidation and allow the electrons to be transferred from EE2 adsorbed onto IONs to the ITO substrate underneath. Therefore, this new sensing platform operates under a particular working principle in which analyte oxidation and subsequent charge transport are separately performed by its individual components.