Abstract: In this study, a time-resolved fluorescence immunochromatographic assay (TRFICA) for detecting aflatoxin B1 (AFB1) and ochratoxin A (OTA) simultaneously was developed. Europium-based time-resolved fluorescent microspheres were used to label anti-AFB1 monoclonal antibody and anti-OTA monoclonal antibody. Various factors such as pH for the activation of fluorescent microspheres, concentration of labeled antibodies, dosage of fluorescent probes, concentration of coating antigens for test line, concentration of goat anti-mouse IgG for quality control line, and sample pretreatment conditions were optimized. Under the optimal conditions, the assay showed half inhibition concentration (IC50) values of 1.58 and 3.91 μg/kg , linear ranges of 0.26–9.73 and 1.14–13.29 μg/kg, and visible limits of detection (vLOD) of 3.70 and 5.55 μg/kg for AFB1 and OTA, respectively. The cross-reactivity rates of this method with aflatoxin analogues and ochratoxin B were 12%–62% and 58%, respectively, without cross-reactivity with other mycotoxins. The recoveries of the two toxins spiked in corn samples were 92%–103%, with coefficients of variation (CV) less than 15%. The results of this method for real samples coincided with those of high performance liquid chromatography (HPLC) and commercial colloidal gold strip. The TRFICA strip was stored at 4 ℃ for more than 5 months with good stability. To sum up, this immunochromatographic strip is sensitive, accurate, rapid and easy to operate, and is very suitable for rapid screening of AFB1 and OTA in food and agricultural products.

Key words: aflatoxin B1; ochratoxin A; time-resolved; fluorescence immunochromatographic strip