Chemical laboratories appear on the mission Remove Council lab from Operative Vargas (levels 20 - 24). There are two of them in the mission and each will have some Council guards around. Oddly enough, it has Skulls faction. It has slightly less hit points than a Lieutenant of the same level. It is destructable, and any Villain or NPC caught in its blast will suffer some damage:
The dangerous chemicals in this lab are highly volatile.