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

[Lab] 16th independent test on WXT — 99.3% on a claimed 98.5%, and the trend is the interesting part

Labbranch of 7 comments

16th independent test on WXT — 99.3% on a claimed 98.5%, and the trend is the interesting part. I will put the method line and the batch identifier up front because that is what makes this checkable. 99.3% and 98.5% — those are the numbers, and they are the ones I am willing to defend. The PDF creation date being…

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7 comments, started 2 years ago
u/wanjiru_varga41 points·2 years ago

Sent one vial to VendorInvestigate 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/bastian_moreauOP25 points·2 years 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/step_therapy_s15 points·2 years ago

HPLC-UV and LC-MS answer different questions

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u/bastian_moreauOP-17 points·2 years ago

Sent one vial to VendorInvestigate 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_pls1 point·2 years ago

Disagree that a lower number is automatically worse. A conservative claim that survives testing is worth more than an optimistic one that does not.

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u/foam_head_fred-25 points·2 years ago

a total of 0.4% tells you less than four named impurities adding to 0.6%

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u/bastian_moreauOP1 point·2 years 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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