for analysis. The injection volume was 20 μL and the auto sampler temperature was set at 5°C. The chromatographic separation of anandamide and 2-AG was performed on a Discovery® HS C18 column 15cm × 2.1mm, 3μm (Supelco: Bellefonte, PA) kept at 40°C. The mobile phase was 10 % water with 1g/L ammonium acetate and 0.1% formic acid, and 90% methanol with 1g/L ammonium acetate and 0.1% formic acid. The flow rate was 0.3 mL/min. The following transition ions (m/z) were monitored in positive multiple reaction monitoring (MRM) mode: anandamide, 348>62 & 348>91; anandamide-d8, 356>62; 2-AG, 379>287 & 279>269; and 2-AG, 387>296. Total run time was 10 min.
