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

[Discussion] can we stop arguing about batch until somebody posts a number

Discussionbranch of 8 comments

Question in the title, detail here: can we stop arguing about batch until somebody posts a number. Area percent is the peak area of your compound over the total integrated area, at one wavelength, on one gradient. It is a relative measure of what the detector saw, not a mass fraction of the vial. UV at 214nm sees the…

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8 comments, started 2 years ago
u/santiago_szabo72 points·2 years ago

Sent one vial to Medutest and PeptideMeter. 99.6% and a claimed 99.0%. Cost me more than the vial and I would do it again.

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u/laila_yilmaz34 points·2 years ago

Sent one vial to Medutest and PeptideMeter.

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

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u/tidy_vialdrawer_watch2820 points·2 years ago·edited

Agreed, and the practical version is: ask for the itemised table.

laila_yilmaz has the distinction right — one is a fraction of the detector signal, the other is a fraction of the mass.

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u/blunt_coldbox2912 points·2 years ago

Batch number and date of analysis, are both on there?

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u/tidy_vialdrawer_pls56 points·2 years ago

How to ask for a batch record without it turning into a negotiation.

One email, three requests: the batch-specific certificate for lot X, the method line behind it, and the storage condition the stability statement was written against. No preamble, no explanation of why you want it.

What comes back is the signal. A full document with the column and gradient printed on it, inside a day, tells you there is a real quality system behind the operation. That is the test I run before I order from anyone new, and it costs nothing.

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u/tuva_aalto38 points·2 years 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/emil_agyeman25 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/dead_space_doug12 points·2 years ago·edited

Pushing back a little: a missing field is usually presentation, not concealment.

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

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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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