HepG2 cells were extracted by a two-step protocol using chloroform/methanol/water based on the Bligh and Dyer approach . 10 μL of acyl-CoA internal standard (IS) containing mixture of C2:0( 13 C2)-CoA, C7:0-CoA, C15:0-CoA and C17:0-CoA with concentration of 3 µM were spiked in the HepG2 cell extracts containing 1×10 6 cells in 100 μL of methanol. To this extract, sonication, 320μL of chloroform and 188 μL of water were added. Samples were vortexed for 1 minute, left to partition on ice for 10 minutes, and centrifuged at 15800 rcf for 15 minutes at 4 °C. 450 μL of the upper aqueous layer was transferred to a new Eppendorf tube. Samples were evaporated to dryness with a Labconco CentriVap vacuum concentrator (Kansas City, MO, USA). The dried samples were reconstituted in 100 μL of methanol/water/isopropanol (1:1:1), and transferred to HPLC vial for LC-MS analysis.