Simultaneous HPLC-APCI-MS/MS quantification of endogenous cannabinoids and glucocorticoids in hair

Hair matrix could retrospectively record association of endogenous cannabinoids (e.g. 2-arachidonoyl glycerol, 2-AG and N-arachidonoyl-ethanolamine, AEA) and glucocorticoids (e.g. cortisol and cortisone) in a myriad of physiological functions. However, depending on the extraction conditions, the spontaneous isomerization of 2-AG to 1-arachidonoylglycerol (1-AG) and the possible rearrangement of O-arachidonoyl ethanolamine (OAEA) to AEA in various sample matrices could be major obstacles encountered in the detection of both 2-AG and AEA. This study aimed to develop a novel method for simultaneous quantification of 2-AG, AEA, cortisol and cortisone in hair. Methanol was used as the incubation solution and an acidic mixture of deionized water and methanol were utilized as mobile phase in order to avert possible rearrangements of both OAEA and 2-AG. The analyses were performed on a high-performance liquid chromatography tandem mass spectrometer with atmosphere pressure chemical ionization in positive mode. The method showed good linearity in the range of 3.0-250pg/mg for AEA, 15.0-1250pg/mg for 2-AG and 1-250pg/mg for cortisol and cortisone. Limit of detection was 1.5pg/mg for AEA, 6.0pg/mg for 2-AG and 0.5pg/mg for cortisol and cortisone. For all four analytes, intra and inter-day coefficients of variation were less than 20% and recovery above 90%. Population analyses in 473 hair samples established that 2-AG was significantly correlated with AEA. 2-AG was significantly and positively correlated with cortisol and cortisone. There was a significant positive correlation of AEA with cortisol, but not with cortisone. Obese participants showed a significantly higher concentration of cortisone and 2-AG. Males showed significantly higher 2-AG and cortisone levels but significantly lower AEA levels than females.