Serum samples were prepared by the addition of 0.5 mL acetonitrile (J.T. Baker) to 0.2 mL serum. The tube was mix-vortexed, centrifuged at 16,000 g for 10 min
Serum samples were prepared by the addition of 0.5 mL acetonitrile (J.T. Baker)to 0.2 mL serum. The tube was mix-vortexed, centrifuged at 16,000 g for 10 min