Lipidomics studies on macrophages - RAW 264.7 cells treated with Kdo₂-Lipid A

*:The analyte concentration was calculated relative to known amounts of three internal standards of varying fatty-acid chain lengths. Within a triplicate sample run, the peak areas of each internal standard were used to calculate a response plot relative to molecular weight. Due to significant overlap of the doubly-charged cardiolipin analytes with other singly-charged lipids, the first 13C isotope of each analyte was used to extrapolate a relative peak area of the analyte to the internal standard. The contributions of overlapping 13C isotope peaks from species with additional double bonds in the acyl chains were subtracted. The absolute amount of analyte in the sample was calculated by correcting the relative peak area ratios for response based on molecular weights. The absolute amount was normalized for the quantity of DNA in the respective sample well in order to correct for inter-sample variations in the number of cells.