Serum Lipid Reference Materials Analysis

All organic solvents were HPLC grade (except nonane, which was 99% pure reagent grade) and purchased from Thermo Fisher Scientific (Waltham, MA, USA). Labeled d₇-cholesterol was purchased from Sigma-Aldrich (USA). Cholesteryl-d₇-palmitate was purchased from Avanti Polar Lipids, (Alabaster, AL, USA). Labeled d₉₈-tripalmitin was purchased from CDN Isotopes, (Pointe-Claire, Quebec, Canada). Two serum reference materials, SRM 1951c Level 1 and Level 2, were provided by the National Institute of Standards and Technology (NIST, Gaithersburg, MD, USA). Five value assigned reference materials (701, 707, 713, 801, and 813) were provided by the Lipid Standardization Program (LSP) at the Centers for Disease Control (CDC). Four units of frozen human serum from de-identified individuals were purchased from Interstate Blood Bank (Memphis, TN, USA) and were used for the preparation of a quality control (QC) pool. After mixing, the pool was distributed into 1 mL aliquots and stored at –80 °C. The 32 de-identified serum samples from normolipidemic (N = 11), hypercholesterolemic (N = 6), hypertriglyceridemic (N = 9), and hyperlipidemic donors (N = 6) were purchased frozen from Bioreclamation IVT (New York City, NY, USA), stored at –80 °C until analysis. All individual donor samples were viral tested before shipment.