Keith I have no problem with the OPCW methodology of taking samples and sending them to independent labs for verification. I have carried out the same procedure myself in the past for base metal content in soil samples. It is a pretty standard procedure if you want to crosscheck results. The primary function of the OPCW is identification of chemicals. The problem arises when determining who manufactured the chemicals and who was in charge of the delivery system? Two very different things. You also need to consider were the attacks targeting
terrorists or civilians? You also need to consider the impartiality of the inspectors on the ground and their qualifications for accurate analysis of a hole in the ground and attributing it to specific munitions. I am sure Assad probably has used chemicals in the past, but were they deliberately targeting non combatants? The Syrian Iraqi
border is porous and munitions can come in from everywhichwhere, including liberated government stockpiles. If the crazies line people up to chop off heads, they obviously have little compunction in gassing civilians wholesale, in order to deceive.
Having read a number of the reports some are emphatic in assigning blame, some are shall we say Dubious. As a battlefield scenario gassing your own people in the winning stages is the hallmark of stupidity and fits no sort of rationale.

I wonder why coalition use of white phosphoros in in densely populated areas of Mosul and in the Islamic State's de facto capital of Raqqa, does not raise the same levels of opprobrium on the (western)World Stage? The mainstream media can suffer very selective amnesia at times!

Many times I largely agree with you, but this time around the propagandists have hijacked the narrative and you are falling for it.