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

unpopular opinion: most of what gets said here about water content is guesswork

Discussionbranch of 8 comments

unpopular opinion: most of what gets said here about water content is guesswork, and I am aware this is a minority view on this board. 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. LC-MS gives…

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8 comments, started 2 years ago
u/dario_vermeulen71 points·2 years ago

Pushing back a little: a missing field is usually presentation, not concealment. Ask for the full document before drawing conclusions.

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u/step_therapy_s22 points·2 years ago

Cosigning. The batch identifier is load-bearing, and a certificate that cannot be tied to the vial in your hand is not about your vial.

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u/camila_lindqvist14 points·2 years ago·edited

Cosigning.

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

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u/clara_restrepoOP6 points·2 years ago

Does the lot on the vial match the lot on the page?

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u/janek_ferrari10 points·2 years ago

HPLC-UV and LC-MS answer different questions

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u/zeynep_zielinski6 points·2 years ago

axis labels included, always

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u/gallbladder_gary3 points·2 years ago

Agreed — the itemised related substances table is the difference between a document and a receipt.

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u/nabila_espinoza1 point·2 years 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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