Bio-derived solvent-based dispersive liquid-liquid microextraction followed by smartphone digital image colorimetry for the detection of carbofuran in cereals

Bio-derived solvent-based dispersive liquid-liquid microextraction coupled with smartphone digital image colorimetry (BDS-DLLME with SDIC) was established to detect carbofuran in cereals. Carbofuran was hydrolyzed to benzofuranol by adding Na2CO3 solution. Bio-derived solvent p-cymene as the extractant and acetic acid as the dispersant were utilized in the DLLME process. The Na2CO3 and acetic acid reacted to generate CO2 bubbles, increasing the contact area between the extractant and sample solution. Thus, the rapid and efficient extraction of benzofuranol was achieved. Fe3O4 nanoparticles catalyzed the oxidative coupling reaction between benzofuranol and 4-aminoantipyrine in the presence of H2O2. Thus, the colorless solution was changed to purple-red which was captured using a smartphone and analyzed with an RGB system, achieving the quantitative detection of carbofuran. The concentration of carbofuran had a good linear relationship in the range of 0.02–20 mg kg−1. The limit of quantification was 0.018 mg kg−1, and the limit of detection was 0.005 mg kg−1. This method was successfully applied to analyze cereal samples with the recoveries of 91.1–113.8%. The BDS-DLLME with SDIC method was used to detect carbofuran with good sensitivity, selectivity, and reliability. The developed method has broad application prospects in rapid and efficient extraction and detection.