*2.2. Spectral Acquisition*

In order to reduce the influence of other impurities on the experimental Raman spectra of five PAEs, the analytical pure PAE samples were used for collecting Raman spectra. For DMP spectral acquisition, 3 mL of analytical pure DMP sample was put in the Raman vial first, then the Raman vial was placed into the liquid measurement accessory of the Raman instrument. After that, the DMP sample is irradiated with laser wavelengths of 785 nm and 852 nm in sequence, and the generated Raman spectrum signal passes through a lens, dichroic mirror, and long pass filter, and is then detected by the Raman spectrometer to obtain DMP Raman spectra at two laser wavelengths. Due to the fact that the positions of the fluorescence peaks do not change with the incident laser wavelength, while the positions of the Raman peaks will change with the incident laser wavelength, matching the Raman spectra of DMP at two incident laser wavelengths through software of OPUS8.7.31 can effectively eliminate fluorescence interference. Finally, the Raman spectrum of DMP that had eliminated fluorescence signal was obtained. The Raman spectra of DEP, DBP, DEHP, and DINP were acquired in the same way. The integration time and number of scans were both set to 6 s and 3, respectively, for five PAEs. Figure 1 shows the schematic diagram of Raman spectrum acquisition.

**Figure 1.** Schematic diagram of Raman spectrum acquisition. PAEs: phthalic acid esters.
