“…Due to their appealing photo-physical properties, such as low autofluorescence background, good photochemical stability, large Stokes shifts nonblinking and nonbleaching emission, tunable fluorescence wavelength, deep penetration into biological samples, and relatively low toxicity, UCNPs are regarded as more promising fluorophores compare to traditional fluorescent material and have been used in medical field (Tang, Gao, Wang, Gao, Gao, Ma, et al, 2015;Wu, Xu, Li, Long, Jiao, Jin, et al, 2017). Recently, UCNPs have been successfully applied for the determination of mycotoxins, antibiotics and bacteria (Hu, Sheng, Zhang, Wang, Wu, & Wang, 2016;Pan, Zhao, & Chen, 2015;Sun, Li, Koidis, & Chen, 2016). To the best of our knowledge, no such research has been conducted to determine ZEN contents in food products using UCNPs.…”