Utilizing the strengths of bioanalysis, LC/MS/MS, and NMR for metabolite identification studies are routinely performed.The goal is to define metabolic pathways for new drug candidates. The studies are often performed in conjunction with mass balance excretion studies, using plasma, urine, or bile samples from mice, rats, dogs, monkeys, or humans. Metabolite identification studies can also be performed in vitro using liver microsomes, hepatocytes, or other preparations from humans or animal species.