Current research has demonstrated the presence of sub parts per billion levels of Sudan dye in paprika fruits during the vegetation process, which is difficult to understand on the basis of the conventional concept of cross-contamination or malicious addition. Detailed surveys on Sudan dyes I-IV in paprika fruits, soils, and agronomic materials used from seven fields of Xinjiang (China) were conducted to investigate the natural contamination. Results revealed that Sudan dyes II-IV were never detected and that Sudan I existed in almost all samples except for the mulching film and irrigation water. The higher total amount of Sudan I in soils, pesticides, and fertilizers compared to coated seeds indicated the combination of Sudan I-contaminated soils and application of Sudan I-containing agronomic materials constitutes a major source of 0.18-2.52 μg/kg levels of Sudan I in fruits during the growth period. The study offers a more reasonable explanation for the previously observed Sudan I in paprika fruits.
Keywords: GPC; Sudan I; UPLC-MS/MS; agricultural environment; agronomic materials; paprika fruit.