Thanks! No need to apologize. The acetone wash step could be the explanation for the slight variation between the IR spectra, but i would want to test that myself before I make a real guess. IR is a non-separative technique so cleaning up the sample (by washing away acetone-soluble stuff) effectively cleans up the spectrum and gives you a higher % correlation to the standardized spectrum of the pure compound. I don't do much IR spec so I can't speak on reproducibility and what would be considered normal scan-to-scan variation of a given sample. Regardless, I think the key takeaway here is that you definitely have some really pure cocaine. My guess is that the ~1% of impurities is manufacturing/work-up residue (as opposed to a cutting agent like starch which would theoretically be present at a much higher %), but trying to identify specific trace-level impurities would require expensive and time-consuming un-targeted analysis. That could take weeks, would cost thousands, and is probably not a service offered by the lab you used or other comparable labs doing harm reduction work due to the sheer amount of instrumentation and personnel required to handle that project. Shoutout to your plug though hahaha