A novel halloysite nanotubes-based hybrid monolith for in-tube solid-phase microextraction of polar cationic pesticides

The accurate determination of polar cationic pesticides in food poses a challenge due to their high polarity and trace levels in complex matrices. This study hypothesized that the use of halloysite nanotubes (HNTs) can significantly enhance the extraction efficiency and sensitivity of these analytes because of their rich hydroxyl groups and cation exchange sites. Therefore, we chemically incorporated HNTs with organic polymer monoliths for in-tube solid-phase microextraction (SPME). This novel hybrid monolith extended service life, improved adsorption capacity, and exhibited excellent extraction performance for polar cationic pesticides. Based on these advancements, a robust and sensitive in-tube SPME-HILIC-MS/MS method was constructed to determine trace levels of polar cationic pesticides in complex food matrices. The method achieved limits of detection of 1.9, 2.1, and 0.1 μg/kg for maleic hydrazide, amitrole, and cyromazine, respectively. The spiked recoveries in five food samples ranged from 80.2 to 100.8%, with relative standard deviations below 10.7%. •HNTs-based monolith enhanced polar cationic pesticide extraction for in-tube SPME.•Adsorption involved cationic exchange and hydrophilic interaction for polar targets.•Monolith was stable and cost-effective and could be reusable up to 35 times.•In-tube SPME-HILIC-MS/MS achieved high sensitivity (LODs = 0.1–2.1 μg/kg).