Polymeric ionic liquid open tubular capillary column for on-line in-tube SPME coupled with UHPLC-MS/MS to determine endocannabinoids in plasma samples

This manuscript describes the development of wall-coated open tubular capillary column with polymeric ionic liquids (PILs) for on-line in-tube solid phase microextraction coupled with ultra high-performance liquid chromatography tandem mass spectrometry (in-tube SPME/UHPLC-MS/MS) to determine anandamide (AEA) and 2-arachidonoyl glycerol (2 A G) in plasma samples. Selective PILs were synthetized from the [VC6IM][Cl], [VC16IM][Br], and [(VIM)(2)C-10]2 [Br] - ionic liquids -by in-situ thermal-initiated polymerization in a fused silica capillary column for in-tube SPME. The synthesis procedure was optimized, and the capillary columns were characterized using spectroscopic and chromatography techniques. The chemically bonded and cross-linked PIL-based sorbent phase (thickness coating: 1.7 mu m) presented high chemical and mechanical stability. Among the sorbents evaluated, the PIL-based capillary, [VC16IM][Br]/[(VIM)(2)C-10]2 [Br] presented the best performance with a sorption capacity of 37,311 ng cm(-3) and 48,307 ng cm(-3) for AEA and 2 A G, respectively. This capillary was reused more than ninety times without significant changes in extraction efficiency. The in-tube SPME-UHPLC-MS/MS method presented a linear range from 0.1 ngmL(-1) to 100 ngmL(-1) for AEA, and from 0.05 ng mL(-1) to 100 ngmL(-1) for 2 A G, with coefficients of determination higher than 0.99, p-value for Lack-of-fit test higher than 0.05 (alpha of 0.05), precision with coefficient of variation (CV) values ranging from 1.6 to 14.0% and accuracy with relative standard deviation (RSD) values from -19.6% to 13.2%. This method was successfully applied to determine AEA and 2 A G in plasma patients with Parkinson's disease. The concentrations in these plasma samples ranged from 0.14 to 0.46 ngmL(-1) for AEA and from <0.05 ng mL(-1) to 0.51 ng mL(-1) for 2-AG. (C) 2018 Elsevier B.V. All rights reserved.