Zn/Al-layered double hydroxide–graphene oxide nanocomposite use in the solid-phase extraction–preconcentration and HPLC determination of diclofenac

Fabrication of MXene/chitosan/polyurea nanocomposite decorated on a graphenized substrate for electro-enhanced solid-phase microextraction of diclofenac followed by its determination using differential pulse voltammetry

A novel solid-phase microextraction fiber based on MXene-chitosan-polyurea (MXene/CS/EPPU) nanocomposite decorated on a graphenized pencil lead fiber (MXene/CS/EPPU/GPLF) was prepared and utilized for electro-enhanced solid-phase microextraction (EE-SPME) of diclofenac (DCF) in biological samples. After extraction and desorption of DCF, it was determined by differential pulse voltammetry (DPV). For this purpose, the working electrode was prepared by deposition of the mentioned MXene/CS/EPPU nanocomposite onto the graphenized pencil lead. The synthesized SPME fiber was characterized using scanning electron microscopy and X-ray diffraction techniques. The effect of various parameters influencing the extraction and the desorption process were investigated, including applied voltage in the extraction and desorption steps, extraction and desorption times, and pH. The developed method exhibited a rather wide linearity in the range 2-1200 ng mL-1 (R2 = 0.985) for the determination of DCF in plasma samples. The limit of detection and the limit of quantification for plasma samples were estimated to be 0.58 and 1.9 ng mL-1 based on the 3Sb/m and 10Sb/m definitions, respectively. The method's accuracy and applicability have been evaluated by the analysis of plasma samples, leading to the relative recoveries in the range 87.0% and 98.0% with the relative standard deviations lower than 3.1%.

Progress in pre-treatment and extraction of organic and inorganic pollutants by layered double hydroxide for trace-level analysis

Continuous release of pollutants into the environment poses serious threats to environmental sustainability and human health. For trace-level analysis of pollutants, layered double hydroxide (LDH) is an attractive option to impart enhanced sorption capability and sensitivity toward pollutants because of its unique layered structure, tunable interior architecture, high anion-exchange capacities, and high porosity (e.g., Zn/Cr LDH/DABCO-IL, Ni/Al LDH, CS-Ni/Fe LDH, SDS-Fe₃O₄@SiO₂@Mg-Al LDH, Boeh/Mg/Al LDH/pC, and Fe@NiAl LDH). In concert with the well-defined analytical methodologies (e.g., HPLC and GC), the LDH materials can be employed to detect trace-level targets (e.g., as low as ∼ 20 fg/L for phenols) in aqueous environments. This review highlights LDH as a promising material for pre-treatment of a variety of organic and inorganic target pollutants in complex real matrices. Challenges and future requirements for research into LDH-based analytical methods are also discussed.

Electrochemically Activated Screen-Printed Carbon Sensor Modified with Anionic Surfactant (aSPCE/SDS) for Simultaneous Determination of Paracetamol, Diclofenac and Tramadol

In this work, an electrochemically activated screen-printed carbon electrode modified with sodium dodecyl sulfate (aSPCE/SDS) was proposed for the simultaneous determination of paracetamol (PA), diclofenac (DF), and tramadol (TR). Changes of surface morphology and electrochemical behaviour of the electrode after the electrochemical activation with H₂O₂ and SDS surface modification were studied by scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The influence of various parameters on the responses of the aSPCE/SDS such as pH and concentration of the buffer, SDS concentration, and techniques parameters were investigated. Using optimised conditions (E_acc. of −0.4 V, t_acc. of 120 s, ΔE_A of 150 mV, ν of 250 mV s⁻¹, and t_m of 10 ms), the aSPCE/SDS showed a good linear response in the concentration ranges of 5.0 × 10⁻⁸–2.0 × 10⁻⁵ for PA, 1.0 × 10⁻⁹–2.0 × 10⁻⁷ for DF, and 1.0 × 10⁻⁸–2.0 × 10⁻⁷ and 2.0 × 10⁻⁷–2.0 × 10⁻⁶ mol L⁻¹ for TR. The limits of detection obtained during the simultaneous determination of PA, DF, and TR are 1.49 × 10⁻⁸ mol L⁻¹, 2.10 × 10⁻¹⁰ mol L⁻¹, and 1.71 × 10⁻⁹ mol L⁻¹, respectively. The selectivity of the aSPCE/SDS was evaluated by examination of the impact of some inorganic and organic substances that are commonly present in environmental and biological samples on the responses of PA, DF, and TR. Finally, the differential pulse adsorptive stripping voltammetric (DPAdSV) procedure using the aSPCE/SDS was successfully applied for the determination of PA, DF, and TR in river water and serum samples as well as pharmaceuticals.