Patent ID: 8263413

Claim:
A method for determining the relative abundance of a lipid of interest, comprising: (i) culturing a first sample of a cell population in a first medium, the first medium including a lipid precursor having a first abundance of at least one isotope; (ii) culturing a second sample of the cell population in a second medium, the second medium including the lipid precursor with a second and different abundance of the at least one isotope, wherein the lipid precursor in each of the samples is incorporated into a biological lipid within the respective samples; (iii) modulating one of the samples of the cell population; (iv) isolating one or more lipids from each of the first and second samples, the lipids from each of the samples including the biological lipid; (v) combining at least a portion of the first sample and a portion of the second sample to form a combined sample, the combined sample comprising the biological lipids from each of the samples; (vi) subjecting the isolated lipids in the combined sample to mass-spectrometry; and (vii) determining the relative abundance of a lipid of interest in the first sample compared to the second sample.