Total oxylipin concentrations in NIST SRM 1950 plasma compared to fresh and commercially obtained human plasma

Authors: KAMPSCHULTE, NADJA - University Of Wuppertal; SCHOLZ, LILLI - University Of Wuppertal; PEDERSEN, THERESA - Eicosis; SNODGRASS, ISABEL - University Of California, Davis; Newman, John; SCHEBB, NILS - University Of Wuppertal

Submitted to: Journal of Lipid Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2026
Publication Date: 3/2/2026
Citation: Kampschulte, N., Scholz, L., Pedersen, T.L., Snodgrass, I.F., Newman, J.W., Schebb, N.H. 2026. Total oxylipin concentrations in NIST SRM 1950 plasma compared to fresh and commercially obtained human plasma. Journal of Lipid Research. 67(4). Article 101011. https://doi.org/10.1016/j.jlr.2026.101011.
DOI: https://doi.org/10.1016/j.jlr.2026.101011

Interpretive Summary: Oxylipins are oxidized polyunsaturated fatty acids (PUFA) such as hydroxy-PUFA and epoxy-PUFA. Total oxylipins are commonly measured following their release from complex lipids by incubating in basic conditions. Standardized methods were validated and reported in an international interlaboratory comparison in 2020. Here, we report the concentrations of total oxylipins in the National Institutes of Standards and Technology Standard Reference Material (NIST SRM) 1950 - Metabolites in Human Plasma. The results for detected compounds are consistent with those in other freshly prepared human plasma samples and analyses reported in different labs. Importantly, we also report 70 oxylipins which were not detected (~<0.5 nmol/L; 0.2 ng/mL). If plasma is collected or stored inappropriately, oxylipins are formed by autoxidation, leading to artificially high levels of total oxylipins. We demonstrate this different commercially available plasma pools of unknown origin, being 100–1000 fold higher. The ranges provided here thus inform which concentration of total oxylipins should be expected in human plasma from healthy subjects, and increase the utility of the NIST SRM 1950 for analytical quality control.

Technical Abstract: Oxylipins are oxidized polyunsaturated fatty acids (PUFA) such as hydroxy-PUFA and epoxy-PUFA. Total oxylipins are commonly analyzed following base hydrolysis as non-esterified oxylipins by means of LC-MS/MS. For that, a standard operation procedure has been developed, which was successfully tested in an international interlaboratory comparison (J. Lipid Res. (2020) 61: 1424–1436). Here, we report the concentrations of total oxylipins in NIST SRM 1950 plasma, which are consistent with those in other freshly prepared human plasma samples and LC-MS/MS analyses in different labs. Hydroxy-PUFA of the long chain PUFA ARA, DHA and EPA occur between 1 and 75 nmol/L (0,3–24 ng/mL) and linoleic acid-derived hydroxy-PUFA up to 400 nmol/L (120 ng/mL). The concentration of ARA, DHA- and EPA-derived epoxy-PUFA ranges between 2 and 20 nmol/L (0.6–6 ng/mL) and LA up to 100 nmol/L (32 ng/mL). We also report 70 oxylipins which cannot be detected (~<0.5 nmol/L; 0.2 ng/mL), mainly multiple hydroxylated PUFA, including so-called SPM, and most isoprostanes. If the plasma is prepared or stored inappropriately, oxylipins are formed by autoxidation, leading to artificially high levels of total oxylipins. This is shown for the concentrations in different commercially available plasma pools of unknown origin, being 100–1000 fold higher. The ranges provided here thus inform which concentration of total oxylipins should be expected in human plasma from healthy subjects, and increase the utility of NIST SRM 1950 for analytical quality control protocols.