This Task Order involves work described in Task A, B, Task F, and Task G of the Statement of Work. The Contractor shall develop and validate assay(s) for the determination of cocaine and its metabolite, benzoylecgonine (BE) in human plasma. The Contractor shall conduct assays using a validated method(s) to determine plasma concentrations of cocaine and BE in plasma samples collected from a Phase 1, one-sequence clinical pharmacokinetic drug-drug interaction study of cocaine and a compound TBD. This task order does not include the analysis of the TBD compound. The clinical study will be carried out at an inpatient facility. A parallel group study design involving approximately 30 healthy volunteers will be used. Each subject will receive intravenous infusions of cocaine at two dose levels in the presence and absence of steady state plasma levels of the TBD compound. In conjunction with the administration of the high dose of cocaine, each subject will have 13 plasma samples drawn for subsequent cocaine and BE analysis, for a total of 26 plasma samples per subject (up to 780 plasma samples for the study).