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A sensor based on graphite nanosheets was fabricated through the electrochemical expansion of a graphite electrode in dimethyl sulfoxide for the sensitive electrochemical determination of enrofloxacin. The modified electrode surface exhibited a distinctive structure of nanoplates, characterized by layer thickness ranging from a few nanometers to ten nanometers. The developed electrode displayed notable electrochemical properties, including a faster charge transfer rate and a larger electrochemically active surface area, which was 1.3 times greater compared to the unmodified electrode. As a result, the sensor improved square wave voltammetric signals for enrofloxacin, exhibiting a 2.4-fold enhancement compared to the unmodified electrode. By optimizing the experimental parameters such as electrode fabrication conditions, pH of analytical solution, and adsorption time for enrofloxacin, the sensor demonstrated good reproducibility and a strong linear correlation over two ranges of enrofloxacin concentrations from 0.05–0.15 μM and 0.1–20 μM. The limit of detection was determined to be 0.002 μM. The sensor was successfully employed for the determination of enrofloxacin in spiked surface water samples before and after treating enrofloxacin by a photocatalytic method. The obtained results exhibited consistency with those obtained using a liquid chromatography-tandem mass spectrometry reference method, and a high recovery rate of 105.5% further confirmed the reliability of the proposed method for enrofloxacin detection. [ABSTRACT FROM AUTHOR]

Ciprofloxacin (Cip), a fluoroquinolone antibiotic, was determined by linear sweep adsorptive stripping voltammetric method using multilayer reduced graphene oxide electrode (m-rGO). The m-rGO electrode was fabricated directly, simply and promptly from graphite platform by potentiostatic technique without further modification. The produced electrode exhibited excellent performance for ciprofloxacin (Cip) determination with a much higher signal of Cip than that on the initial graphite electrode (13.4 times). This dominance of the m-rGO electrode resulted from the large electrochemically active surface area, electrochemical catalysis, suitable functional groups on the electrode surface. Experimental conditions such as the electrode fabrication time, the supporting solution, and accumulation time were optimised to obtain the Cip highest signal. A Cip analytical method established under the optimal conditions had a good linear relationship between the Cip signal with its concentration range from 0.5 to 20 µM (R2 = 0.9953). The method showed a low detection limit (LOD = 0.078 µM), satisfactory reproducibility (RSD = 1.50%), and high accuracy. Cip concentration in a spiked lake water sample determined by the proposed method with acceptable precision (RSD = 5.59%) and trueness (recovery = 94.2–106.3%) was comparable with LC-MS/MS method. [ABSTRACT FROM AUTHOR]

It is essential to develop new nanomaterials able to improve sensing performance of electrochemical sensors for determination of heavy metal pollutants. In this work, a novel nanoscale metal–organic-framework material (Yb-MOF) with Ytterbium (Yb) rare-earth metal core and benzenetricarboxylic (BTC) ligands was prepared in aqueous conditions using hydrothermal approach. The results have revealed highly porous structure of the as-synthesized material with specific active area up to 1166 m2 g−1. A sensing platform was then constructed by drop-casting Yb-MOF onto glassy carbon electrode for detection of two most commonly found heavy metal ion pollutants (Cd2+ and Pb2+) in water sources. The nanoporous structure of Yb-MOF is very profitable to the selective preconcentration of targeted metal ions. The detection limits were estimated to be 3.0 ppb, 1.6 ppb for Cd2+ and Pb2+ species, respectively. This work provides a new electrochemical sensing platform for fast and sensitive in-situ detection of water contaminants. [ABSTRACT FROM AUTHOR]