A microplate cover assembly which is compatible with manual workstations or robotic handling systems used for high throughput screening. The cover assembly includes a cover, a pressure plate and a layer of sealing material. The cover is shaped such that when it is engaged with a microplate, the cover exerts a compressive force on the pressure plate, which in turn disperses the force in a substantially uniform manner across the layer of sealing material. The cover and pressure plate also include laterally-extending tabs which allow it to be engaged with or disengaged from a microplate in a fully automated fashion.

An apparatus for random access storage and retrieval of a plurality of microplates is provided. The apparatus includes a plurality of microplate racks arranged in a stack. Each of the racks is mechanically engaged with a plurality of support columns and each of the columns has a plurality of locking devices corresponding to the plurality of racks. The apparatus also includes a lift, coupled to the support columns, for moving the stack or a portion thereof, and a controller, coupled to the lift and the locking devices. The controller is responsive to a signal to access a desired rack or microplate to cause actuation of one or more of the locking devices corresponding to the rack adjacent to the desired rack or microplate, followed by actuation of the lift, thereby moving a portion of the stack a sufficient distance to allow access to the desired rack or microplate.