Sensitive Quantification of Cannabinoids in Milk byAlkaline Saponification–Solid Phase Extraction Combined withIsotope Dilution UPLC–MS/MS

摘要

Maternal exposure to marijuana during the lactation period—either active or passive—has prompted concerns about transmission of cannabinoids to breastfed infants and possible subsequent adverse health consequences. Assessing these health risks requires a sensitive analytical approach that is able to quantitatively measure trace-level cannabinoids in breast milk. Here, we describe a saponification–solid phase extraction approach combined with ultra-high-pressure liquid chromatography–tandem mass spectrometry for simultaneously quantifying Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) in breast milk. We demonstrate for the first time that constraints on sensitivity can be overcome by utilizing alkaline saponification of the milk samples. After extensively optimizing the saponification procedure, the validated method exhibited limits of detections of 13, 4, and 66 pg/mL for THC, CBN, and CBD, respectively. Notably, the sensitivity achieved was significantly improved, for instance, the limits of detection for THC is at least 100-fold moresensitive compared to that previously reported in the literature.This is essential for monitoring cannabinoids in breast milk resultingfrom passive or nonrecent active maternal exposure. Furthermore, wesimultaneously acquired multiple reaction monitoring transitions for ¹²C- and ¹³C-analyte isotopes. This combined analysislargely facilitated data acquisition by reducing the repetitive analysisrate for samples exceeding the linear limits of ¹²C-analytes.In addition to high sensitivity and broad quantitation range, thismethod delivers excellent accuracy (relative error within ±10%),precision (relative standard deviation <10%), and efficient analysis.In future studies, we expect this method to play a critical role inassessing infant exposure to cannabinoids through breastfeeding.