Behind the scenes of the OPCW chemical testing lab
18 September 2013 Last updated at 20:43 BST
The Organization for the Prohibition of Chemical Weapons (OPCW) is the body responsible for investigating the alleged chemical weapons attack in Syria.
Samples of contaminated material have been shipped by the UN investigators to the OPCW laboratories for analysis.
BBC reporter Anna Holligan visited the OPCW laboratory in The Hague, in The Netherlands.