How does Sigma Aldrich check for 99% purity of compounds?

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Juan Hugo Mecchia Ortiz

Dear Sreeja S Putran,

I'm not sure which test use Sigma Aldrich, I suppose that depends on the sample. But I think that is very probable that they perform NMR analysis, mass spectrometry, and or HPLC or GC analysis. NMR is really useful to check the structure and purity of compounds. I hope this information would be useful for you. Regards.

Juan