Uric acid
Uric acid was a component of urine.
In 3189, an atomic scan on Philippa Georgiou's synovial fluid revealed it had 81 milligrams per deciliter (mg/dl) of uric acid. (DIS: "The Sanctuary")
In a deleted scene from the Star Trek: The Next Generation seventh season episode "Genesis", Data describes the smell in a USS Enterprise-D shuttlebay as a mixture of methane, uric acid and ammonia. [1]