15 s hete d8

High performance liquid chromatography (HPLC)-grade methanol, acetonitrile, chloroform and 2-propanol were purchased from Merck (Darmstadt, Germany). HPLC-grade water was prepared using a Milli-Q water purification system (Millipore, Burlington, MA, USA). Analytical grade acetic acid and commercial standards used for biomarker identification were purchased from Sigma-Aldrich (St. Louis, MO, USA). Internal standards (IS) including Arachidonic acid-d8, 15(S)-HETE-d8, Leukotriene-B4-d4 and Platelet-activating factor C-16-d4 (PAF C-16-d4) were purchased from Cayman Chemical (Ann Arbor, MI, USA) [18 (link)].

Lidocaine (2%) and proxymetacaine (0.5%) eye drops were from Moscow Endocrine Plant (Moscow, Russia) and Alcon-Couvreur (Puurs, Belgium), respectively. The Schirmer test tear strips were from Haag-Streit (Bern, Switzerland). Butylated hydroxytoluene (BHT) was from Sigma-Aldrich (St. Louis, MO, USA). The deuterated oxylipins standards 6-keto PGF1α-d4, TXB2-d4, PGF2α-d4, PGE2-d4, PGD2-d4, LTC4-d5, LTB4-d4, 5(S)-HETE-d8, 12(S)-HETE-d8, 15(S)-HETE-d8, Oleoyl Ethanolamide-d4, EPA-d5, DHA-d5 and AA-d8 were from Cayman Chemical (Ann Arbor, MI, USA). Solid-phase lipid extraction cartridge Oasis^® PRIME HLB was obtained from Waters (Eschborn, Germany). Other chemicals were from Sigma-Aldrich, Amresco (Solon, OH, USA), or Serva (Heidelberg, Germany) and were at least reagent grade.