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c/coa·submitted 1 months ago by u/teodor_lokken

does water content actually matter or is it forum lore at this point

Labbranch of 6 comments

Trying to get a straight answer on this: does water content actually matter or is it forum lore at this point. LC-MS gives you identity; UV purity gives you a relative quantity. A document with the first and not the second, or the reverse, is answering half the question. UV at 214nm sees the peptide bond and picks up…

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6 comments, started 1 months ago
u/amylin_amyamylin0 points·1 months ago

Net peptide content is the fraction of the powder that is actually peptide once counterion, water and residual solvent are accounted for. A 99% pure acetate salt can still be about 85% peptide by mass.

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u/purity_pedantMOD1 point·1 months ago

Left up and flaired Explainer. This is the answer we keep linking, written properly.

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[removed]1 point·1 months ago

[removed by moderator]

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u/teodor_lokkenOP1 point·1 months ago

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

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u/purity_pedantanalytical1 point·1 months 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/ahmed_rasmussen1 point·1 months ago

axis labels included, always

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About c/coa

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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