Narrow-Bore Tube Magnetic Solid-Phase Extraction Method Utilizing Ionic Liquid-Modified Magnetic Nanoparticles for the Preconcentration and Determination of Catechin in Grape Juice

A magnetic solid-phase extraction (MSPE) approach is developed as an efficient and simple method on the basis of the modification of magnetic nanoparticles using an ionic liquid in order to preconcentrate and extract catechin from grape juice samples. A narrow-bore tube (NBT) containing the sample was used to carry out the extraction in a simple and efficient manner. Using scanning electron microscopy (SEM), Fourier transfer infrared (FT-IR) spectroscopy, and X-ray spectroscopy (EDX), the specifications of the synthesized nanoparticles modified with 2-hydroxyethyl ammonium chloride ionic liquid were scrutinized. The impact of various parameters on catechin extraction was assessed. Under optimized conditions (i.e., sample volume of 10 mL, pH 3, 14 mg of sorbent, 20-min desorption time, and elution with 3.0 mL of 0.15 mol L^–1 phosphate buffer at pH 10), the relative standard deviation and limit of detection (LOD) were found to be 1.63% and 0.141 µg mL⁻¹, respectively, for seven replicate determinations using HPLC–UV. Based on the obtained experimental results, the maximum adsorption capacity of the sorbent for catechin was 61 mg g⁻¹. Eventually, to determine the applicability of the developed technique, the method was a success when utilized to analyze the catechin content of the samples of grape juice, indicating a recovery range of 93.4–99.5%.