Effective Extraction and Determination of 3-Nitropropanoic Acid in Sugarcane Samples Based on Magnetic Solid-Phase Extraction Coupled with HPLC-MS/MS

To reduce the risk associated with 3-nitropropanoic acid (3-NPA) contamination, an efficient and accurate analytical method for 3-NPA determination in sugarcane samples was established by combining magnetic solid-phase extraction (MSPE) with high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS). Owing to the hydrogen bonding and hydrophobic interactions, the mixed strong cation exchange (MCX) magnetic adsorbent showed effective extraction ability toward 3-NPA. Only 2 mL of organic solvent was consumed during the MSPE procedure, and the operation time was short (5 min). The limits of detection were 0.02 μg kg−1 for sugarcane juice and 0.04 μg kg−1 for sugarcane. The developed method showed satisfactory spiked relative recoveries (96.9–105.4%) and good precision values (RSD 1.4–9.7%). MCX-MSPE cleanup provided partial mitigation of matrix suppression, with the absolute matrix effect value rising from 39.4% to 57.1%. This study provides an efficient analytical alternative for the determination of 3-NPA in sugarcane samples.