Rapid assay of picogram level of sudan I in hot chilli sauce by flow injection chemiluminescence

A novel chemiluminescence method for the assay of sudan I was designed using flow injection with chemiluminescence detection. The proposed method was based on the increment effect of sudan I on the chemiluminescence intensity in the luminol–KIO₄ system. The increment of chemiluminescence intensity was correlated with the sudan I concentration in the range from 0.1 to 10 pg ml⁻¹, and the determination could be performed in 0.5 min in flow rate of 2 ml min⁻¹, including sampling and washing, giving a throughput of 120 h⁻¹ with a relative standard deviation of less than 5.0%. The method had been successfully applied to the assay of sudan I in Pixian douban, Golden mark guilin chilli sauce and Golden mark satay sauce, and the recovery was 90.0–103.8%.