LC-MS/MS-ESI method for simultaneous quantitation of three endocannabinoids and its application to rat pharmacokinetic studies.

An LC-MS/MS-ESI method has been validated for simultaneous estimation of the three endocannabinoids; N-arachidonoylethanolamine (AEA), N-oleoylethanolamine (OEA) and palmitoylethanolamide (PEA), in surrogate matrix using AEA-d (4) as an internal standard with highest sensitivity over the existing methods. Simple precipitation was used to extract analytes and these were subsequently analyzed on a monolithic column. Linear response function was established over the concentration range 12.3 to 1225 pg/ml for AEA (r > 0.994); 0.70 to 641 ng/ml for OEA (r > 0.999) and 0.54 to 321 ng/ml (r > 0.998) for PEA. The intra- and inter-day precision values met the acceptance to criteria as per US FDA guidelines. Analytes were found to be stable in the battery of stability studies. The method was applied to quantify endogenous levels of analytes in rat plasma.