and CDDGS. Samples were first homogenized using a spatula, and then weighed (10 g) into 50 mL conical tubes, to which 15 mL of water for CWDGS and MWDGS, and 35 mL of water for CDDGS was added. Then EC-d5 (100 µL, 10 ug/mL in water) was added as internal standard (IS). Samples were vigorously mixed on a VX-2500 vortexer (VWR, Radnor, PA) at 4°C for 2 h and then centrifuged at 17000 g and 4°C for 30 min using an Eppendorf 5430 centrifuge (Hauppauge, NY). The supernatant was recovered and washed with hexane (5 mL) to remove neutral lipids. NaCl (4 g) was added to the de-oiled aqueous extract (10 mL) and extracted with MTBE in a solvent-tosample ratio of 4:1 (by vol). After 1 min of vigorous vortexing, samples were centrifuged at 2000 g and 4°C for 10 min using an Allegra X-12R centrifuge (Beckman Coulter) and the top MTBE layer was recovered and dried under a gentle stream of nitrogen until about 100 µL remained. Cautions were taken not to let the extract completely dry. All the sample extracts were stored at -20°C until analyzed.