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c/coa·posted 1 year ago by u/ignacio_silva

anyone else notice area percent kicking in around week 25

Question Long Haul ×9 Cold Box ×1 Clean Column ×1

Trying to settle this properly because the thread from last year went in circles.

The claim: COA matters. The counter-claim: it is measurement error. Both sides have been asserting it confidently for about 18 months without either producing anything.

What would actually settle it is 19 people measuring the same thing the same way. I have started; my numbers are below. They lean one way but not strongly enough for me to declare victory.

If you have data, post the data. If you have an opinion, flair it as an opinion.

3,956 up / 99 down98% upvoted65 commentsid 1y1sm619 Sep 2024

65 comments

30 in this archive, depth 6

best — the order this archive was captured in

u/kavya_verhoeven513 points·1 year ago

post the whole document, not the headline number

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u/anya_moreau255 points·1 year ago

post the whole document, not the headline number

Adding to this: purity is doing more work than the comment implies.

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u/teodor_lokken573 points·1 year ago·edited

Sent one vial to PeptideMeter and VendorInvestigate. 96.8% and 94.2%. Cost me more than the vial did and I would do it again.

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u/soren_zamora359 points·1 year ago

purity and net content are two different numbers, same vial

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u/honest_syringe24-16 points·1 year ago

What is the method line say? Not the technique, the actual method.

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u/tidy_vialdrawer_watch313 points·1 year ago

axis labels included, always

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u/amylin_amyamylin242 points·1 year ago

axis labels included, always

Counter-anecdote: opposite result, same dose. Which mostly tells us the variance is huge.

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u/halima_boateng66 points·1 year ago

the related substances line is where the story is

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u/aleksi_eriksen51 points·1 year ago

purity and net content are two different numbers, same vial

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[deleted]23 points·1 year ago

[deleted]

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u/chidi_demir193 points·1 year ago

Three years on this site and the questions have not changed at all. Which is depressing or reassuring depending on the day.

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u/laila_wojcik53 points·1 year ago

the batch number or it did not happen

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u/mikkel_correia152 points·1 year ago

Yeah, 96.8% area is not the problem, the missing impurity breakdown is the problem.

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u/valeria_karlsen116 points·1 year ago

Strongly agree. Mass% and area% are answering different questions on the same document.

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u/reflux_report39 points·1 year ago·edited

the related substances line is where the story is

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u/tidy_vialdrawer_pls24 points·1 year ago

Disagree. What you are describing is consistent with related substances, not with what you concluded.

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u/foam_head_fred6 points·1 year ago

no "is this good?" without saying what the compound and claimed purity are

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u/amylin_amyamylin5 points·1 year ago·edited

Batch number and date of analysis? Both are load-bearing.

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u/coa_collectorMOD116 points·1 year ago

Tracking number removed. It identifies both ends of a shipment.

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u/freya_baptista118 points·1 year ago
that is the funniest sentence i have read on this site
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u/sofia_danquah80 points·1 year ago

Cosigning. The batch number is load-bearing information.

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u/ignacio_silva21 points·1 year ago

That is net peptide content, not purity. Different number, different meaning.

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u/ignacio_silvaOP30 points·1 year ago

PDF metadata is checkable in fifteen seconds

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u/joaquin_ivaturi23 points·1 year ago

Cosigning. The batch number is load-bearing information.

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u/laila_yilmaz0 points·1 year ago

the related substances line is where the story is

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u/aleksi_eriksen0 points·1 year ago

the method line is doing real work, not just window dressing

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u/anya_correia85 points·1 year ago

What is the method line say? Not the technique, the actual method.

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u/ignacio_silvaOP39 points·1 year ago

The confident tone is doing a lot of work that the evidence is not.

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u/tomas_lehtinen22 points·1 year ago

no "is this good?" without saying what the compound and claimed purity are

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u/ignacio_silva35 points·1 year ago

I am going to push back on this slightly.

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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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