Magnetic Cotton Stalk Biochar for Rapid and Eco‐Friendly Extraction and Determination of Triazole Pesticides in Fruit Juices

ABSTRACT Triazole fungicides (TFs) are widely used but pose health risks. Among them, cyproconazole, paclobutrazol, tebuconazole, metconazole, and diniconazole have high exceedance rates and exhibit hepatotoxicity and nephrotoxicity, necessitating simple and sensitive detection methods. Therefore, this study employed magnetic cotton stalk biochar (Fe 3 O 4 /CSBC) prepared via a one‐step impregnation–pyrolysis process for rapid magnetic solid‐phase extraction (MSPE) of TFs in juice samples. Key extraction parameters were optimized using liquid chromatography–ultraviolet detection (LC–UV): 5 mg of adsorbent, 2 mL of sample, and 5 min of adsorption time were sufficient for complete extraction, followed by elution with 100 μL of acetonitrile for 5 min. Quantitative analysis was performed using LC–MS/MS, and isotope‐labeled internal standards effectively corrected for matrix effects. The linear R 2 value was > 0.995, recovery rates ranged from 85.76% to 119.68%, and the limit of detection (LOD) was 0.012–0.052 ng·mL −1 . This method does not require centrifugation, has low solvent consumption, promotes the resource utilization of agricultural waste, and supports sustainable analytical practices. Therefore, future investigations may explore its application for detecting a broader range of pesticides, additives, and contaminants.