Headspace solid-phase microextraction and gas chromatography−mass spectrometry for determination of cannabinoids in human breast milk

Human milk is a highly complex biological fluid, and it is considered to be the ideal food for infants during their first months of life. On the other hand, licit and illicit substances consumed by the breastfeeding woman can pass into the milk and may cause harmful effects to the infant. Drug extraction from this matrix can be an analytical challenge due to its high protein and lipid content. Since marijuana is the most commonly used illicit drug at the global level, the aim of the present study was to develop a headspace solid-phase microextraction (HS-SPME) method for the determination of Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN) in human breast milk using gas chromatography−mass spectrometry. The limits of detection and quantification were 10 and 20 ng/mL, respectively, for all analytes. Calibration curves were linear over a concentration range of 20.0–200 ng/mL (r2 = 0.99). Intraday and interday precision was not greater than 13.3% (relative standard deviation), and accuracy bias ranged from 5.5 to 17.9%. One hundred and nine human milk samples were randomly collected and analyzed. Only two samples were confirmed to be THC positive at 20 and 31 ng/mL. CBD was also detected in one milk sample. The present method has shown to be reliable for determination of THC, CBD and CBN in human breast milk in a very low volume sample (0.05 mL). Also, the HS-SPME procedure was demonstrated to be a rather promising, low cost and environmental-friendly technique. In addition, the SPME is very suitable for automated extraction procedure.