A Disposable Pipette Extraction‐UHPLC‐MS/MS Method Based on Removal of Phospholipids to Determine Anandamide, 2‐Arachidonoylglycerol, Cannabidiol, and Δ9‐Tetrahydrocannabidiol in Plasma Samples

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Cannabidiol (CBD) and Δ9‐tetrahydrocannabinol (THC), the main components of Cannabis sativa plants, can interact with specific cell receptors known as cannabinoid receptors (CBs). The endogenous compounds anandamide (AEA) and 2‐arachidonoylglycerol (2‐AG) are CB agonists, and, alongside enzymes, they constitute the endocannabinoid system (ECS) and take part in neuromodulation. Several LC‐MS/MS methods have been developed to quantify these compounds in biological matrixes, but a fast and simple method that can determine these analytes in plasma samples simultaneously is not available. Here, we propose a disposable pipette extraction technique containing a zirconia‐based sorbent (DPX(Zr)) combined with UHPLC‐MS/MS analysis to determine CBD, THC, AEA, and 2‐AG in plasma samples, simultaneously. The method combines simple protein precipitation (PPT) with a one‐step DPX procedure to remove phospholipids, one of the most common endogenous interferents in biological samples. Optimization of the combined PPT‐DPX sample preparation method reduced the matrix effect and improved the sensitivity of the analytical method. The validated DPX(Zr)‐UHPLC‐MS/MS method reported LLOQs of 0.1 ng mL−1 for AEA and 2‐AG and 1 ng mL−1 for CBD and THC. The method demonstrated intra‐ and interassay accuracy and precision of less than 20% for the LLOQ, and less than 15% for the other calibration points. Additionally, no carryover or significant matrix effect was observed. We applied this method to determine AEA, 2‐AG, and CBD in plasma samples obtained from obsessive‐compulsive disorder patients treated with CBD.