Trichlorofenapyr, also known as acaricide, is a broad-spectrum insecticide widely used to control red spider mites in crops such as cotton, fruit trees, and tea. On October 27, 2017, the International Agency for Research on Cancer of the World Health Organization released a preliminary list of carcinogens for reference, and dichlorofenapyr was included in the three categories of carcinogens. In 2023, it will also be included in China's "Key Control New Pollutant List (2023 Edition)".Common reference standards are tested using the temperament method.Due to the unique structure of the compound (as shown in Figure 1), a liquid chromatography-mass spectrometry system can be used to thermally decompose it through the heating effect of an ion source, generating a positive ion with an m/z of 251, which can be detected by liquid chromatography-mass spectrometry.