KHAN SHEIKHOUN: How Like-Sarin is a Sarin-Like Substance?

The OPCW has analysed samples from Khan Sheikhoun in April containing what they have identified as ‘sarin or a sarin-like substance’. They know that much, even if they are not sure how it got there or who is responsible.
But how much actually is that? Throughout the OPCW report we find the cumbersome expression sarin or a sarin-like substance. Why not just sarin, pure and simple?
All a non-chemist like me can understand from this is that we are dealing with some nasty stuff, but there is no definite confirmation it is sarin pure and simple. Of course, a non-chemist also has no idea how impure a sample or how different a molecule would need to be to count as merely of a substance like sarin; nor would we know how much more impure or different it could be before becoming unlike sarin. So we non-chemists could easily be bamboozled in these matters.
One thing we do know is that the sarin the Syrian government produced and gave up for destruction in 2013 was referred to by all concerned as sarin, pure and simple. To produce sarin with military grade purity is not easy. To produce improvised versions, however, is within the capacity of insurgents in Syria.
Given that there are already open questions about motive, means and opportunity, as I indicated in my previous blog, then if there is doubt about even the weapon as well, the case for blaming Assad looks decidedly uncertain.

This post was published at 21st Century Wire on JULY 8, 2017.