Effervescent tablet-enhanced acidic ionic liquid-assisted in situ solvent formation magnetic solid-phase extraction for the detection of three phenolic pesticides in four kinds of crop flour samples

Abstract

There are some notable drawbacks of ordinary magnetic effervescent tablets including their quick disintegration, hygroscopicity, and impracticability for field use. In order to solve the above problems for further extraction and preconcentration of three phenolic pesticides from crop flour samples, an effervescent tablet-assisted acidic ionic liquid-based in situ solvent formation magnetic solid-phase extraction (ETA-AIL-MSPE) technique was developed. In contrast to conventional imidazole ionic liquids, acidic ionic liquids can be employed as an acid source for effervescent processes in addition to being used as extractants. Not only does this reduce the need for organic solvents, but the production of CO₂ by the effervescent tablet also provides a rapid dispersion effect, removing the requirement for further dispersion stages and streamlining the experiment. The magnetic effervescent tablet is made of Na₂CO₃ as an alkaline source, [BMIM][HSO₄] as extractant and acidic sources, NaCl as a viscosity modifier, and Fe₃O₄ as magnetic nanoparticles. The Plackett–Burman design and the central composite design were used to screen and optimize three key variables (93 mg of Na₂CO₃, 451 mg of AIL, and 37 mg of Fe₃O₄), respectively. Through the integration of high-performance liquid chromatography-diode array detection (HPLC-DAD), the ETA-AIL-MSPE technique provided enhanced recoveries of 85.0–107.2% and limits of detection of 0.14–0.17 μg kg⁻¹ for three representative species (ioxynil, bromoxynil, and dinoseb) in four different types of crop flour samples. For both intra-day and inter-day precision, the relative standard deviations were below 7.7%. Generally, the recently developed technique is convenient, efficient and environmental-friendly, and it has great potential for on-site sample preparation for the detection of phenolic pesticides in crop flour samples.