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c/coa·submitted 3 months ago by u/cesar_ivaturi

do related substances actually matter or is it forum lore at this point

Labbranch of 12 comments

The title is the whole question — do related substances actually matter or is it forum lore at this point — but here is why I am asking. The PDF creation date being later than the analysis date is usually a re-issue or a re-export. It is worth one question and it is not evidence of anything on its own. Ask what the…

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12 comments, started 3 months ago
u/soren_nkemelu202 points·3 months ago

I would not read a rounded figure as evasive. Plenty of documents round to one decimal as house style.

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u/india_generic_g136 points·3 months ago

What does the method line actually say? Not the technique — the column and the gradient.

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u/fatima_wojcik196 points·3 months ago

Asked for the storage condition behind the stability statement. Got it in a sentence. It is a two-line email and almost nobody sends it.

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u/cato_achebe0 points·3 months ago

Asked for the storage condition behind the stability statement.

Agreed, and the practical version is: ask for the itemised table. If it exists, you get it.

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u/santiago_szabo110 points·3 months ago

HPLC-UV and LC-MS answer different questions

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u/cesar_ivaturiOP45 points·3 months ago

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

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u/priya_palacios0 points·3 months ago

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

This is the sentence to take away. The rest of the thread is footnotes to it.

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u/stablecoin_steve10 points·3 months ago

Water content 3.8%, acetate 6.2%, purity 99%, net peptide about 90% of label weight. All four numbers honest, and I had to read it twice.

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u/bastian_moreau67 points·3 months ago

Spent four months confusing area% and mass% in every post I made here. One explainer thread and it clicked permanently.

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u/tove_ogunleye53 points·3 months ago

the related substances line is where the story is

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u/tomas_lehtinen16 points·3 months ago

chromatogram or it did not happen

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u/cato_achebe-29 points·3 months ago

ask for the storage condition the stability statement was written against

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How to read a certificate of analysis and what it does and does not tell you. Area% versus mass%, identity versus quantity, water content, related substances, acetate counterions, and the difference between a vendor-supplied COA and an independent test on the vial you actually received.

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