Your comment is a good illustration of the point I was making about claims and evidence. If someone makes a claim you need to check what evidence there is to support it.
I wrote that “there is no evidence that rebel groups fighting in Syria have ever possessed or had access to Sarin”, and you dispute this with three reported claims.
Claim №1 is an article which says rebels captured some “barrels” of Sarin when they seized a Syrian army base.
The claim comes from a single rebel fighter and there are reasons to doubt it. For a start, the Syrian government insists that none of its Sarin stocks were lost or captured.
Sarin is complicated stuff that has to be mixed just before use — you can’t just store it in barrels. The Sarin would be useless unless the rebels also had the relevant munitions and knew how to fill and fire them. You can’t just attach a bomb to a bottle of Sarin and hope that it works.
There’s more about Sarin weapons here:
Claim №2: One member of the UN commission, Carla Del Ponte, said there were “strong, concrete suspicions but not yet incontrovertible proof” that rebels had used Sarin.
Del Ponte has never produced the evidence to support her suspicions, and nobody has yet come up with any proof.
Claim №3: “Turkish newspapers reported in May 2013 that twelve people from Syria’s al Qaeda-linked al-Nusra Front, had been detained in Adana. They allegedly had been planning an attack inside Turkey and were in possession of two kilograms of sarin.”
The Turkish authorities denied the media claims that Sarin had been found. Some “unknown chemical materials” were sent off for analysis. Six of the people arrested were quickly released.
Your last point is about mustard gas, not Sarin. There have been reports of rebels using mustard gas, which I am not disputing here.