Isopropanol and methanol

All solvents used were of LC–MS analytical grade. Acetonitrile was purchased from Carlo Erba (Val De Reuil, France), isopropanol and methanol from Fisher Scientific (Laughborough, UK) and formic acid 98–100% from Chem-Lab (Zedelgem, Belgium). Lauric acid was purchased from Acros Organics (>99%), myristic acid from Sigma Aldrich (>99.5%), myristoleic acid from Sigma Aldrich (>99%), pentadecanoic acid from Sigma Aldrich (>99%), palmitic acid from Fluka (analytical standard), 9-palmitoleic acid from Fluka (analytical standard), margaric acid from Sigma Aldrich (>98%), 10-Z-heptadecenoic acid from Cayman Chemical Company (>98%), stearic acid from Fluka (analytical standard), oleic acid from Fluka (analytical standard), linoleic acid from Sigma Aldrich (>99%), linolenic acid from Sigma Aldrich (>99%), arachidic acid from Cayman Chemical Company (>98%), bihomo-γ-linolenic acid from Cayman Chemical Company (>98%), arachidonic acid from Sigma Aldrich (>99), 5,8,11,14,17-cis-eicosapentanoic acid from Fluka (analytical standard), 7,10,13,16,19-cis-docosapentaenoic acid from Cayman Chemical Company (>98%), 4,7,10,13,16,19-cis-docosahexaenoic acid from Sigma Aldrich (>98%) and lignoceric acid from Cayman Chemical Company (>98%).

LC-MS analytical grade solvents were used. Acetonitrile was purchased from Carlo Erba (Chaussée du Vexin, Val De Reuil, France), isopropanol and methanol from Fisher Scientific (Laughborough, UK) and formic acid 98–100% from Chem-Lab (Zedelgem, Belgium). RA was commercially available from Cayman Chemical (Ann Arbor, MI, USA). 14OPA, 10OPA, 9OPA, 8OPA, 7OPA, 6OPA, 16OSA, 12OSA, 10OSA, 9OSA, 8OSA, 7OSA and 6OSA were synthesized at the Laboratory of Organic Chemistry, National and Kapodistrian University of Athens, and the details of their synthesis will be published elsewhere. The standards were characterized by ¹H and ¹³C NMR spectroscopy and HRMS. Their purity was studied by LC-HRMS and was found to be >97%.

All solvents used were of LC-MS analytical grade. Acetonitrile was purchased from Carlo Erba (Val De Reuil, France), isopropanol and methanol from Fisher Scientific (Loughborough, UK) and formic acid 98% to 100% from Chem-Lab (Zedelgem, Belgium). 10-Hydroxydecanoic acid was purchased from Fluorochem (Derbyshire, UK) and was of the highest available quality. 10-HDA, 3-hydroxydecanoic acid, decanedioic acid and 2-dodecenedioic acid were synthesized in the Laboratory of Organic Chemistry (National and Kapodistrian University of Athens). All physical data were in agreement with literature data and their purity was >97%.