Maresin

Optima grade methanol (MeOH), acetonitrile (ACN), isopropanol (ISP), and acetic acid (AcOH, > 98% pure) were purchased from Fisher Scientific (Pittsburg, PA, USA). UHPLC-grade methyl tert-butyl ether (MTBE) and hexane were also purchased from Fisher Scientific (Pittsburg, PA, USA). Methyl formate (> 98% pure) was purchased from Acros Organics (Morris Plains, NJ, USA). Ammonium acetate (NH₄OAc) was purchased from Fisher Scientific (Fair Lawn, NJ, USA). Deionized water was obtained through filtration via a Millipore Q-Plus (Elix^®35, Molsheim, France). For study 1, native SPM standards: resolvin D1 (RvD1), resolving D2 (RvD2), resolving D3 (RvD3), resolvin D5 (RvD5), resolving E1 (RvE1), maresin (MaR1), and protectin (PD1), and deuterated SPM standards: resolvins (RvD1-d₅, RvD2-d₅, RvD3-d₅, RvE1-d₄) maresin (MaR1-d₅), and leukotriene B4-d₄ were purchased from Cayman Chemicals (Ann Arbor, MI, USA). C18 SPE cartridges (Supel^TM-Select HLB SPE 30 mg loading, 1 mL volume) were purchased from Supelco Analytical (Bellefonte, PA, USA). For study 2, lipid standards were purchased from Cayman Chemical (Ann Arbor, MI, USA), Santa cruz Biotechnology, Inc (Dallas, TX, USA) and Avanti polar Lipids, Inc (Alabaster, AL, USA), as summarized in Supplementary Materials: Table S1.