Quantitative Lipid Analysis Protocol

Nuclease P1 from Penicillium citrinum, phosphodieasterase I and II, alkaline phosphatase from bovine intestinal mucosa, DNase I and DNase II, benzonase 99%, BHT, deferoxamine mesylate and pentostatin were purchased from Sigma-Aldrich (Steinheim, Germany). RNase T1 was from Thermo Fisher Scientific (Waltham, MA, USA) and RNase A from Roche Diagnostic GmbH, (Mannheim, Germany). The 3 kDa cut-off filters were obtained from Millipore (Bedford, OH, USA). Solvents (HPLC-grade) were purchased from Fisher Scientific. 2′-Deoxyadenosine monohydrate were purchased from Berry & Associates Inc. (Dexter, NY, USA). Isotopic labeled internal standards of 5′R-cdA, 5′S-cdA, 5′R-cdG, 5′S-cdG and 8-oxo-dA (see Supplementary Materials) were prepared according to the previously reported procedures [21 (link)]. Ultrapure water (18.3 MΩ.cm) distilled and deionized water (Milli-Q water) were purified by a Milli-Q system (Merck-Millipore, Bedford, OH, USA). Chloroform, methanol and n-hexane were purchased from Merck (HPLC-grade). Anhydrous sodium sulfate (Na₂SO₄) was purchased from Carlo Erba (Val de Reuil Cedex, France). All fatty acid methyl esters (FAME) used as reference standard for GC analyses were purchased from Sigma-Aldrich or Fluka (Steinheim, Germany) without further purification. Analytical silica gel thin-layer chromatography was performed on Merck silica gel 60 plates.