All solvents and reagents employed were ≥98% purity unless otherwise indicated, including cyclohexane, acetonitrile, methanol, ethanol absolute, ammonia solution 30% (w/w), and water, all sourced from Fisher Chemicals (Waltham, MA, USA). Hexane, ethyl acetate, potassium hydroxide, sodium hydroxide, sodium chloride, potassium chloride, calcium chloride, magnesium chloride, monosodium phosphate, disodium phosphate, glucose, trimethyl phosphite, acetic acid, and formic acid were obtained from Merck (Darmstadt, Germany). The free radical initiator 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V70) was procured from FUJIFILM Wako Chemicals (Tokyo, Japan) and N-methyl benzohydroxamic acid (NMBHA) was prepared in our laboratory following the methodology outlined in a prior publication . Tyrode's solution was prepared weighting and dissolving in water the appropriated amounts of the following salts to obtain the concentration of NaCl 8 g/L, KCl 0.2 g/L, CaCl2 0.2 g/L, MgCl2 0.1 g/L, NaH2PO4 0.05 g/L, NaHCO3 1 g/L, and glucose 1 g/L. The pH was adjusted with 1M solution NaOH to 7.4. The PUFAs used in the in vitro oxidation were AA and EPA from Merck (Darmstadt, Germany), DHA from Santa Cruz Biotechnology (Dallas, TX, USA), and ALA from BLDpharma (Shanghai, China). The PUFA esters employed were DHA ethyl ester, AA methyl ester, and EPA methyl ester from Merck (Darmstadt, Germany) and ALA methyl ester purchased from Fisher Chemicals (Waltham, MA, USA). Regarding oxylipin standards, individual stock solutions at 1 µmol/L of 131 oxylipins (purity >95%) were prepared dissolving the appropriate amounts in H2O:CH3CN mixture (i.e. 20% CH3CN). This includes 72 commercially available enzymatic oxylipins and NEO-PUFAs purchased at Cayman Chemical (Ann Arbor, MI) as individual standard or premixed solution and 59 NEO-PUFAs obtained by total synthesis in our laboratory following previously developed procedures and purity-checked by NMR . As internal standards (IS); the same mixture of oxylipins commonly employed in our laboratory for quantitative methods published elsewhere weighting the appropriate amounts of compounds and dissolving it in H2O (20% CH3CN) to obtain a concentration of 3.25 mg/L each. This includes non-natural odd number analogues of oxylipins C19-16-F1t-PhytoP and C21-15-F2t-IsoP, and an isotopically labelled D4-10-epi-10-F4t-NeuroP.