*5.3. Samples*

The samples of culinary herbs were purchased from supermarkets and local (organic food) stores in Belgium and included 14 single herbs and 51 herb/spice mixtures. More details on the samples are provided in Table S2. Prior to the analysis, the herb samples were finely ground and homogenized. The samples of human urine were provided by volunteers.

## *5.4. Sample Preparation*

Two grams of the herb sample was weighed in a 50 mL PP tube. After addition of 25 mL of ACN, the sample was vigorously shaken on an overhead shaker for 30 min and centrifuged for 10 min at 3180× *g*. Ten mL of supernatant was transferred in a 15 mL PP tube and evaporated at 45 ◦C under a stream of nitrogen until a volume of approximately 1 mL. Subsequently, H2O containing 5% NH3 was added to a total volume of 10 mL. After thorough vortexing and centrifugation (10 min at 3180× *g*) the extract was subjected to further clean-up. Oasis® MAX SPE cartridges were conditioned with 3 mL MeOH and 3 mL H2O. Three mL of supernatant was loaded onto the cartridge and washed with 3 mL H2O containing 5% NH3. After a brief drying step, the target analytes were eluted with 3 mL MeOH and collected in 15 mL PP tubes. The eluate was evaporated until dryness at 45 ◦C under a stream of nitrogen. The residue was reconstituted in 250 μL H2O:ACN (80:20, v/v) and filtered through filter units for 5 min at 14,000× *g*.

Five mL of urine was transferred to a 15 mL PP tube, to which 5 mL H2O containing 2% HCOOH was added. After vortexing, the sample was centrifuged for 10 min at 3180× *g*. For the clean-up, Oasis ® HLB cartridges were conditioned with 3 mL MeOH and 3 mL H2O. Six mL of supernatant was loaded onto the cartridge and washed with 3 mL H2O. After a brief drying step, the target analytes were eluted with 3 mL MeOH and collected in 15 mL PP tubes. The eluate was evaporated until dryness at 45 ◦C under a stream of nitrogen. The residue was reconstituted in 500 μL H2O:ACN (80:20, v/v) and filtered through filter units for 5 min at 14,000× *g*.
