Answer: The BYK-9076 standard's IR was last measured on 16 May 2015 at 15:15:00 (GMT05:30) per the only IR record for the standard in this data drop. That is the measurement timestamp embedded in the spectrum report. (The document also carries a later rendering timestamp, 22-07-2026 14:27:32, but that is the view/export date of the spectrum file, not a measurement date.)

Caveats: The structured record exp-9076-000BYK9076STD is marked STUB — it is an unlinked sample entry whose only content is the link to this IR file. The date above comes from the PDF's text layer, not from a field in the record itself, and there is no separate analytical/ELN entry confirming additional IR runs of the standard. If "last" implies there were earlier runs, the records don't contain them.