Chilled methanol:water, 80:20, was added to the vials (300 µL). Samples were spiked prior extraction with a mixture of isotope labeled metabolites (Mix 2 QReSS Kit, Cambridge Isotope Labs, Tewksbury, MA) to account for extraction variability among samples. Samples were extracted in a Precellys homogenizer (3x15s; 5,500 rpm). Homogenized tissue (200 µL) was transferred to a clean Eppendorf vial. Samples were centrifuged at 10,000g for 3 min at 4°C. Samples were stored overnight at -24°C to allow for precipitation of remaining proteins. Samples were centrifuged again at 13,000g for 15 min at 4°C. Supernatant (150 µL) was recovered in LCMS glass vials with 300 µL insert, spiked with a mixture of isotope labeled metabolites (Mix 1 QReSS Kit, Cambridge Isotope Labs) and stored at 4°C before analysis. Mix 1 internal standard mixture was used to check for injection accuracy and platform performance due to the large number of samples and extended batch run time.