The Pine Bluff Arsenal says it shipped a small amount of mustard agent samples to a laboratory for analysis as it prepares to destroy more chemical weapons.

The shipment Tuesday, by air, was the fourth of several shipments the arsenal will make. More are planned.

The samples will be used to verify the characteristics of the mustard agent stored in the one-ton containers at the arsenal. The containers are the last munitions set for destruction at the arsenal. The mustard, a blister agent, is the only chemical agent stored in ton containers at the arsenal.