A novel microflow LC-MS method for the quantitation of endocannabinoids in serum.
Endocannabinoids (ECs) represent a class of endogenous, small molecules that bind and activate the G-protein coupled EC receptors. They are involved in a variety of fundamental biological processes and are associated with many disease states. Endocannabinoids are often present in complex matrices and at low concentrations, complicating their measurement. Here we describe a highly sensitive method for the quantitation of the following ECs in serum: N-arachidonoylethanolamine (anandamide), N-oleoylethanolamine, N-palmitoylethanolamine, 2-arachidonoylglycerol, and its inactive isomer 1-arachidonoylglycerol. On-line sample trapping coupled with separation via microflow liquid chromatography and detection by tandem quadrupole mass spectrometry results in the necessary sensitivity for accurate quantitation of ECs in less than 50μL of serum, without the need for off-line solid phase extraction. Limits of quantitation between 1.2 and 13.4pg/mL were achieved, representing a significant increase in sensitivity compared to previous methods using analytical flow rates. An additional benefit of microflow chromatography is the reduction of solvent consumption by more than two orders of magnitude. The experimental utility of the assay is demonstrated through the analysis of serum from hibernating bears to assess seasonal changes in circulating EC concentrations.
Colorado State University, Proteomics and Metabolomics Facility, 2021 Campus Delivery, Fort Collins, CO, 80523, USA.
Jay S
JS
Kirkwood
Colorado State University, Proteomics and Metabolomics Facility, 2021 Campus Delivery, Fort Collins, CO, 80523, USA.
Corey D
CD
Broeckling
Colorado State University, Department of Mechanical Engineering, 1374 Campus Delivery, Fort Collins, CO 80523, USA.
Seth
S
Donahue
Colorado State University, Proteomics and Metabolomics Facility, 2021 Campus Delivery, Fort Collins, CO, 80523, USA. Electronic address: Jessica.prenni@colostate.edu.
Jessica E
JE
Prenni
D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D063388:Endocannabinoids / Q000097:blood*; D006605:Hibernation; D007536:Isomerism; D057230:Limit of Detection; D012015:Reference Standards; D015203:Reproducibility of Results; D012212:Rheology / Q000379:methods*; D012621:Seasons; D053719:Tandem Mass Spectrometry / Q000379:methods*; D001503:Ursidae / Q000097:blood
D063388:Endocannabinoids
Chromatography; Endocannabinoids; LC–MS; Microflow; Quantitation; SRM; Sensitivity; Serum