For Method 2 and 3, 8 150-µL-aliquots of the lab plasma pool were spiked with 20 uL of the CAL4 solution of endocannabinoids and prepared until dryness. They were reconstituted in 24 µL of injection solution (concentration factor (CF) 6.25), pooled and distributed over vials to create a dilution series containing 0, 2, 4, 8, 16, 24, 32 or 40 µL of CF 6.25 plasma, 10 µL of mixed working solution of deuterated standards and 40, 38, 32, 24, 16, 8 or 0 µL of injection solution, respectively. This resulted in plasma samples with a CF ranging from 5 to 0.25, which were analyzed in triplicate using LC-MS/MS with 2F-AEA as a PCIS.