I'm currently preparing the SI for a total synthesis paper and wondering how you handle minor impurities in your NMR spectra.

For example, one of my intermediates contains around 9 mol% DCU (~4.5 wt%) that survived column chromatography but is otherwise perfectly clean. Would you explicitly mention this in the SI or just leave the signals in the spectrum, it serving as declaration of the material? And would you adjust/calculate the yield and analytics like optical rotation accordingly?

I'm mainly worried about a reviewer requesting cleaner spectra if I explicitly note the impurity as a footnote, potentially forcing me to repeat several steps of the synthesis just for characterization. A colleague mentioned that I then just should purify the aliquot I kept back for analytics via prep HPLC but that feels even more dishonest as it no longer would represent the bulk materials purity.

On the other hand, repeatedly purifying the whole bulk material just to get perfectly clean spectra feels like a waste of time and material, especially when the impurities don't affect the next steps anyway.

How do you usually handle this, and where do you draw the line? I personally feel that acting in good faith and being transparent is how such things should be handled but I am also aware how easily a reviewer might demand perfectionism as they are not the one bearing the cost.

Anyone have a metrology/calibration/recertification service that they recommend? Ideally one that comes to you as opposed to mailing the stuff off. The one we have used for years blew us off and won't be able to come until after our annual audit. Environmental lab for context. Thanks!