Record Smashed: Antimatter Trapped for 16 Minutes

and we were able to contain it for a few short minutes before we had to open it.

http://www.trekplace.com/article07.html

(Abridged - pun noted)

In "The Naked Time" (Star Trek episode #7), Riley locks himself in the engine room. While trying to regain access to the engine room from just outside that room's entrance.

SCOTT (to an engineer): Get up to my office and pull the plans for this bulkhead.

SCOTT: Engineering to bridge.

SCOTT (to Kirk): Captain, you can't mix matter and antimatter cold! We'd go up in the biggest explosion since --

KIRK: We can balance our engines into a controlled implosion.

SCOTT: That's only a theory. It's never been done.

(I'm not a Trekkie who continued to follow the series after the original, but I DID remember this line from the original series. Surfing for it brought up the above link.)