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A novel potentiometric sensor, based on carbon paste electrode (CPE), modified with ion-imprinted polymer (IIP) and multi-walled carbon nanotubes (MWCNTs), is introduced for detection of chromium (III). The IIP nanomaterial was synthesised and characterised by using scanning electron microscopy and Fourier Transform Infrared. The modification of the CPE with the IIP (as a ionophore) resulted in an all-solid-state Cr(III)-selective sensor. However, the presence of appropriate amount of MWCNTs in the electrode composition was found to be necessary to observe Nernstian response. The optimised electrode composition was 76.7% graphite, 14.3% binder, 5% IIP, and 4% CNT. The proposed sensor exhibited Nernstian slope of 20.2 ± 0.2 mV decade−1in the working concentration range of 1.0 × 10−6−1.0 × 10−1 mol L−1(52 µg L−1–5.2 g L−1), with a detection limit of 5.9 × 10−7 mol L−1(30.68 µg L−1) and a fast response time of less than 40 s. It displayed a stable potential response in the pH range of 2–5. It exhibited also high selectivity over some interfering ions. The proposed sensor was successfully applied for the determination of Cr(III) in real samples (sea, river water and soil). [ABSTRACT FROM PUBLISHER]

Abstract A novel nano-sized imprinted polymer/multi-walled carbon nanotube (MWCNTs)-based potentiometric sensor is introduced for lactic acid (LA) sensing in dairy products. The imprinted polymer was synthesized using allyl amine (AA) and ethylene glycol dimethacrylate as functional monomer and cross-linker, respectively. It was demonstrated that the amide linkage was created between LA and AA during copolymerization reaction which was finally hydrolyzed when removing template from the synthesized MIP. It was also shown that the MIP cavities, compatible with LA anion, were created during polymerization reaction which influenced the potentiometric response behavior of the MIP-based electrode. This novel potentiometric sensor is a carbon rod electrode, coated with a membrane consisting of the MIP nanoparticles (2.5%), MWCNTs (2%), dibutylphthalate (DBP) (65%), poly-vinyl chloride (PVC) (28.5%) and tetra phenyl phosphonium bromide (TPPB) (2%). The active ion sensed by the electrode is the LA anion formed at elevated pH condition. The sensor exhibited Nernstian slope of 30.3 ± 0.4 mVdecade−1 in the working concentration range of 1.0 × 10−1to 1.0 × 10−6 mol L−1 with detection limit of 7.3 × 10−7 mol L−1. The sensor displayed a stable potential response in the pH range of 5–8 and fast response time of less than 60 s. It exhibited also high selectivity over the interfering species. The proposed sensor was successfully applied for the determination of LA in real samples (milk and yoghurt). Graphical abstract fx1 Highlights • A new nano-sized imprinted polymer was synthesized for lactic acid recognition. • Ally amine was used as the functional monomer for LA imprinting. • LA-MIP was used as ionophore of the membrane coated graphite rod electrode. • Including of MWCNTs in the membrane improved the electrode performance. • The electrode exhibited response time of 60 s and DL of detection limit of 0.73 µM. [ABSTRACT FROM AUTHOR]