*4.3. Sample Pre-Concentration*

An aliquot (6.0 mL) of the extracts (equal to 1.5 g sample) was transferred into glass tubes and evaporated at 45 ◦C under a gentle stream of nitrogen to ~0.2 mL. Then, 50 μL ISTD mixture (Section 4.1) and water were added into the tubes to obtain 0.5 mL of volume, followed by sample reconstitution by vortex-mixing for 20 s. Finally, samples were filtered through the PTFE syringe filters into the HPLC vials and analyzed by the LC-ID-MS/MS method. In this case, the sample pre-concentration was 3-fold. The concentrations of ISTDs were: TEA-13C2 (83 μg/kg), ALT-d6 (33 μg/kg), AOH-d3 (17 μg/kg), TEN-d3 (17 μg/kg), and AME-d3 (17 μg/kg).

#### *4.4. Sample Clean-Up on Mixed-Mode Cation Exchange Cartridges*

An aliquot (5.0 mL) of the extracts was diluted with 35 mL 1% (*v*/*v*) acetic acid in water in new PP centrifuge tubes, which were capped. After homogenization by handshaking for 10 s, the diluted samples were subjected to SPE clean-up on Strata-XL-C cartridges (3 mL, 200 mg). Cartridges were conditioned with 3.0 mL methanol, followed by 3.0 mL water and 3.0 mL 1% (*v*/*v*) acetic acid in water. Diluted samples (40 mL) were passed the cartridges through the dropwise method. Then, cartridges were washed with 3.0 mL water, followed by 3.0 mL *n*-hexane. Afterwards, the cartridges were dried under vacuum for 1.0 min and the samples were eluted with 5.0 mL methanol into glass tubes. Samples were then evaporated and reconstituted as written in Section 4.3.

#### *4.5. Sample Clean-Up on Silica Cartridges*

Sunflower oil samples (3.00 g) were weighed into the PP centrifuge tubes, followed by the addition of 6.0 mL *n*-hexane. The oils were completely dissolved in the tubes by vortex-mixing for 5 s. Samples were subjected to SPE clean-up on Strata-Si-1 cartridges (6 mL, 500 mg). Cartridges were conditioned with 6.0 mL methanol, followed by 6.0 mL *n*-hexane. The samples dissolved in *n*-hexane were passed the cartridges through dropwise method. Then, cartridges were washed with 6.0 mL *n*-hexane. Afterwards, the cartridges were dried under vacuum for 1 min and samples were eluted with 6.0 mL methanol into glass tubes. Samples were then evaporated and reconstituted as written above.

#### *4.6. Sample Preparation for Sunflower Seed Samples*

Sunflower seed QC samples (2.00 g) were extracted with 8 mL methanol/water (80/20, *v*/*v*) mixture, then the extracts were de-fattened with 2.0 mL *n*-hexane (Section 4.2). The hexane layer was discarded, and 0.5 mL extract was diluted with ISTD mixture (50.0 μL). Afterwards, extracts were filtered through the PTFE syringe filters into HPLC vials and analyzed by LC-ID-MS/MS.
