A poisonous compound that contaminates the water table of the Federation colony on Beta Agni II, an emergency arranged by the collector Kivas Fajo to lure the Enterprise-D.
Tricyanate appears in the Next Generation episode The Most Toys. The colony on Beta Agni II reports that its underground water has been poisoned with the substance, and the only agent able to neutralise it is hytritium, a compound too unstable to beam.
The Enterprise buys hytritium from the trader Kivas Fajo, and Data ferries it across by shuttlecraft. On the final run the shuttle explodes, and the crew believe the android has been destroyed.
At Beta Agni II the treatment works, but Geordi La Forge and Wesley Crusher notice that tricyanate does not occur naturally there and that the contamination is too tidy. The poisoning was sabotage, staged so that Fajo could kidnap Data for his collection.