System suitability test kits

Methanol, 2-propanol, dichloromethane, water, and ammonium acetate were purchased from VWR International, LLC (Radnor, Radnor, PA, USA). All of these products were of HPLC grade. Internal standard (ISTD) kits (containing ISTDs for 13 lipid classes), pike standards with quality control plasma kits, SelexION tuning kits, and system suitability test kits for quantitative lipidomic analysis of human samples were purchased from AB Sciex Germany GmbH (Darmstadt, Germany). The composition of ISTD standard mixtures containing isotope-labeled lipid molecules was previously described in detail [64 (link),65 (link)]. Lipids were extracted from the plasma samples using a modified Bligh-Dyer method [66 (link)].

Methanol, 2-propanol, dichloromethane, water, ammonium-acetate were purchased from VWR International, LLC (Radnor, Radnor, PA, USA). All of them were of HPLC grade. Internal standard (ISTD) kits for quantitative lipidomic analysis of human samples were bought from AB Sciex Germany GmbH (Darmstadt, Germany). The kits contain ISTDs for 13 lipid classes including ceramides (Cers), cholesterolesters (CEs), DGs, acylceradmides (ACer), fatty acids (FAs), hexosylceramides (HexCers), lactosylceramides (LacCers), LPCs, LPEs, PCs, phosphatidylethanolamines (PEs), SMs, and TGs. The composition of ISTD standard mixtures containing isotope-labelled lipid molecules were described in detail previously [18 (link)]. Spike standards with quality control plasma kits, SelexION tuning kits, and system suitability test kits were also obtained from AB Sciex Germany GmbH.