Halloysite-based sorbents: Synthesis, characterization, and applications in sample preparation

Abstract

Halloysite nanotubes (HNTs), naturally occurring aluminosilicate clay minerals, possess unique structural and physicochemical properties that make them highly promising sorbents for solid-based extraction methods. Their tubular structure, high surface area, and inherent adsorption capacity enable efficient capture of analytes from complex matrices. This review comprehensively examines the application of HNTs in solid-phase extraction (SPE) and its miniaturized variants, such as solid-phase microextraction (SPME) or micro SPE (μ-SPE), focusing on their use in isolating analytes from environmental, beverage, food, and biological samples. Key aspects covered include the synthesis and modification of HNT-based composites to enhance extraction selectivity and efficiency, the assessment of the environmental impact and greenness of the extraction methodologies, and the characterization techniques used to elucidate the structure-property relationships of the HNT-based materials. The review highlights the significant potential of HNTs to advance sample preparation technologies by offering sustainable and efficient extraction processes across a broad range of analytical disciplines.