*2.7. Blind Sample Detection*

Twenty milk and ten pork blind samples were provided by Guangdong Provincial Key Laboratory of Food Quality and Safety, which were tested by the developed TRFM-ICG and LC-MS/MS as the confirmatory method. It should be noted that we did not know the concentration of DEX in each sample. Each sample was tested in triplicate; the correlation between the two methods was compared; and the consistency of the results reflects the reliability of the method.

The working parameters of the LC-MS/MS method are given in the Supplementary Materials. The sample pretreatment of milk and pork was consistent with the national standards [30,31].
