As far as I am aware the whole material was used for the dating here – that is what the weighed components suggest – and we don’t have any remaining sample in our archives with these sample numbers. I think the position taken here was that we only had permission for dating and not other research – and at that time, the measurements needed as much material as possible. It is true that it is normal practice to retain some material for further checks in routine dating and we do normally do this – so I can see that other labs may have made different decisions.
Apparently Oxford needed at least 16mg to produce reliable results (they cut their 50mg sample into three). Strange that Tucson needed only 7mg.