Sometimes you may have a 50:50 mixture of compounds and be able to unambiguously assign the signals. Usually 5% of an imputiry will not affect your structural analysis

Thank You Teodoro Kaufman

95% to 100%

Yes, 5% impurity will not interfare in NMR analysis. I think you should go for NMR and LC-MS both.

it depend some:

1-Your experience in NMR field

2- Your actual requierements

most peoples prefers a purity better than 95%. Always NMR has the capability for differencing between main product and impurities through the DOSY-based experiments.

May be if the compound is only 90% purity can I proceed to H1 and C13 NMR?