One-step Magnetic SERS Platform for Rapid Capture and Sensitive Quantification of Sudan I–IV in Chili Powder and Tomato Sauce Samples

As illegal synthetic colorants in food, Sudan dyes possess carcinogenic potential and can severely threaten human health following long-term intake. Rapid and sensitive detection of Sudan dyes in complex food matrices (e.g., chili powder and tomato sauce) remains a critical challenge for food safety supervision. Herein, a facile and sensitive detection strategy targeting Sudan I, II, III, and IV was established by combining magnetic substrates with surface-enhanced Raman spectroscopy (SERS). The influence of Au NPs loading on SERS analytical performance was systematically investigated, and FSA-3 was identified as the optimal substrate. Under optimized conditions, the limits of detection (LODs) for Sudan I–IV in chili powder and tomato sauce were determined to be 0.75–11.5 μg/kg, with satisfactory recoveries ranging from 84.5% to 110%. Compared with previously reported SERS methods and conventional analytical techniques, the proposed method exhibits excellent resistance to matrix interference capability and enables sensitive and efficient detection. This work provides a reliable and efficient alternative for the rapid screening of Sudan dye residues in complex food matrices, holding great promise for practical food safety applications.