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c/coa·submitted 2 years ago by u/tomas_lehtinen

[Discussion] related substances are doing more work than we give it credit for

Discussionbranch of 7 comments

related substances are doing more work than we give it credit for, and I am aware this is a minority view on this board. Sent one vial to VendorInvestigate and Janoshik. 98.9% and a claimed 98.0%. Cost me more than the vial and I would do it again. The PDF creation date being later than the analysis date is usually a…

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7 comments, started 2 years ago
u/stablecoin_steve231 points·2 years ago

UV at 214nm sees the peptide bond and picks up almost everything; at 280nm you are looking at aromatics only. Which wavelength the number came from is part of the number.

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u/katrin_girard271 points·2 years ago

HPLC-UV and LC-MS answer different questions

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u/tidy_vialdrawer_watch222 points·2 years ago

Not quite. Two labs with different gradients can resolve a close-eluting impurity differently and both be reporting honestly.

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u/chidi_demir212 points·2 years ago

That is not what the method line says. It names the technique; it does not certify the operator.

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u/andres_restrepo62 points·2 years ago

axis labels included, always

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u/valeria_girard47 points·2 years ago

Did you ask for the batch-specific document, or is this the catalogue one?

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u/tomas_lehtinenOP41 points·2 years ago

Correcting myself upthread: I said the date was missing and it is on the second page, which I had not scrolled to.

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