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c/coa·submitted 10 months ago by u/valeria_karlsen

[Question] related substances — what am I missing here

Questionbranch of 8 comments

related substances — what am I missing here — that is what I am asking, and I have already read the wiki twice. Ask what the stability statement was written against — temperature, light, and whether it was the lyophilised powder or the reconstituted solution. Those are three different claims. The PDF creation date…

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8 comments, started 10 months ago
u/bastian_moreau769 points·10 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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[deleted]318 points·10 months ago

[deleted]

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u/emeka_beaulieu248 points·10 months ago

post the whole document, not the headline number

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u/valeria_girard122 points·10 months ago·edited

My first certificate had a compound name, a percentage and a logo. I thought that was normal. It is not, and now I know what to ask for.

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u/cormac_pereira94 points·10 months ago

ask for the storage condition the stability statement was written against

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u/nikhil_lindqvist75 points·10 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/bastian_moreau184 points·10 months ago

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.

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u/gallbladder_gary-38 points·10 months ago

axis labels included, always

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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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