Signal amplification for simultaneous determination of two proton pump inhibitors in biological matrix based on newly synthesized metal organic framework and polymeric film

Electrochemical sensor based on 3D-printed substrate by masked stereolithography (MSLA): a new, cheap, robust and sustainable approach for simple production of analytical platforms

The development of miniaturized, sustainable and eco-friendly analytical sensors with low production cost is a current trend worldwide. Within this idea, this work presents  the innovative use of masked stereolithography (MSLA) 3D-printed substrates for the easy fabrication of pencil-drawn electrochemical sensors (MSLA-3D-PDE). The use of a non-toxic material such as pencil (electrodes) together with a biodegradable 3D printing resin (substrate) allowed the production of devices that are quite cheap (ca. US$ 0.11 per sensor) and with low environmental impact. Compared to paper, which is the most used substrate for manufacturing pencil-drawn electrodes, the MSLA-3D-printed substrate has the advantages of not absorbing water (hydrophobicity) or becoming crinkled and weakened when in contact with solutions. These features provide more reproducible, reliable, stable, and long-lasting sensors. The MSLA-3D-PDE, in conjunction with the custom cell developed, showed excellent robustness and electrochemical performance similar to that observed of the glassy carbon electrode, without the need of any activation procedure. The analytical applicability of this platform was explored through the quantification of omeprazole in pharmaceuticals. A limit of detection (LOD) of 0.72 µmol L^-1 was achieved, with a linear range of 10 to 200 µmol L^-1. Analysis of real samples provided results that were highly concordant with those obtained by UV-Vis spectrophotometry (relative error ≤ 1.50%). In addition, the greenness of this approach was evaluated and confirmed by a quantitative methodology (Eco-Scale index). Thus, the MSLA-3D-PDE appears as a new and sustainable tool with great potential of use in analytical electrochemistry.

An electrochemical sensor based on an Eriochrome Black T polymer and deep eutectic solvent for the simultaneous determination of omeprazole and lansoprazole

Here we report the fabrication of an electrochemical sensor for the simultaneous determination of the concentrations of omeprazole (OMZ) and lansoprazole (LAN) in biological fluids and pharmaceuticals in Britton-Robinson buffer solution (pH 6.0). The sensor was prepared by bulk modifying a carbon paste electrode with deep eutectic solvent (DES), followed by carrying out electropolymerization of Eriochrome Black T (EBT) at this electrode. The presence of DES increased the extent of the polymerization of EBT on the surface of the electrode, and this increase led to better OMZ and LAN electron transfer kinetics at the electrode surface. The modified electrode was evaluated and characterized by performing cyclic voltammetry, electrochemical impedance spectroscopy, scanning electronic microscopy, and Fourier-transform infrared spectroscopy. The best responses were obtained in drug-free Britton-Robinson buffer solution (pH 6.0) after 600 s of stirring at the open circuit potential. Linear relationships were obtained between the anodic peak currents and the concentrations of OMZ and LAN in the ranges of 0.010-0.276 and 0.010-0.300 μM, with detection limits of 0.006 and 0.009 μM, respectively. Satisfactory results were also obtained for the analysis of OMZ and LAN in real samples. The excellent sensitivity and easy regeneration and modification of this electrode with DES followed by the polymerization of EBT make this electrode relatively highly applicable for flow methods.