Trying to search for such information usually gets me onto Anti-Semitic websites. I can't even find information about the supposedly Polish government examination of the chamber without finding myself on StormFront or another websites.
I've never heard of this claim but it sounds very much like the classical Leuchter Report as used by Holocaust deniers. Emory University's Holocaust Denial on Trial is an excellent resource to find simple counter-arguments to most of the rubbish that Holocaust deniers spout. Check out this page regarding your own question.
Another question - if the holocaust deniers deny that Zylkon B was used for death-camp murders, then why do they think the Nazi authorities were ordering it to be manufactured in such large quantities and specifying that it should be odourless?
Why would anyone need odourless Zyklon B for delousing or even Chemical warfare? It'd be really useful to have if you want to murder someone in such a way that they are severely incapacitated before they start panicking and tearing at the camp uniforms you want to re-use, but no other practical use comes to mind.
Zyklon B was a brand name for cyanide gas, stored in canisters. Chemically seen, there is no thing as Zyklon B, so there is no way that a chemist could detect Zyklon B. I have seen used canisters at the permanent exposition in Auswitsch. The cyanide gas itself dissolves in air.