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c/coa·posted 2 years ago by u/ismael_eriksen

[Discussion] we are measuring water content at the wrong time and calling it noise

Discussion Receipts ×9 Slow Clap ×1

I have had 13 orders now and I keep a table, so here is the honest summary rather than a vibe.

Material has been consistent. Communication has not. Shipping has varied by about 28 days on nominally the same lane, which matters more in summer than in February.

The independent number came back 98.4% against a claimed 98.6%, which I read as agreement rather than a discrepancy — inter-lab variance on this assay is a point or two either way and treating one lab as ground truth is how people end up in pointless arguments with vendors.

Batch number is in the comments. Ask if you want the method.

2,424 up / 814 down75% upvoted43 commentsid 4kab2y18 Dec 2023

43 comments

22 in this archive, depth 4

best — the order this archive was captured in

u/zaid_balogun95 points·2 years ago

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

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u/receptor_bias_rick73 points·2 years ago

Did they give you the chromatogram or just the summary line?

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u/nadia_fonseca86 points·2 years ago

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

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u/coa_collectorarchivist0 points·2 years ago

PDF metadata is checkable in fifteen seconds

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u/freya_baptista1 point·2 years ago

PDF metadata is checkable in fifteen seconds

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

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u/sig_figs_sammod · analytical1 point·2 years ago

the batch number or it did not happen

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[removed]35 points·2 years ago

[removed by moderator]

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u/ismael_eriksenOP16 points·2 years ago

Sent one vial to Janoshik and VendorInvestigate. 97.4% and 97.2%. Cost me more than the vial did and I would do it again.

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u/cesar_ivaturi49 points·2 years ago·edited

Titration speed is a side-effect dial far more than an efficacy dial.

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u/anecdata_annie-37 points·2 years ago

redact your own name, not the vendor's batch details

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u/ismael_eriksenOP1 point·2 years ago

Asked BCH for the batch-specific COA and they sent it within six hours, full document, batch number, date, everything. That is the baseline.

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u/vito_chowdhury0 points·2 years ago

Asked BCH for the batch-specific COA and they sent it within six hours, full document, batch number, date, everything.

Disagree on that part. 98.7% and 96.2% on the same vial is normal.

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u/cormac_pereira1 point·2 years ago

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

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u/clara_restrepo34 points·2 years ago

the batch number or it did not happen

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u/cormac_pereira17 points·2 years ago

Respectfully this is a sample of one presented as a finding.

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u/freya_baptista5 points·2 years ago·edited

axis labels included, always

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u/mikkel_correia6 points·2 years ago·edited

Respectfully this is a sample of one presented as a finding.

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

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u/wrong_network_w2 points·2 years ago

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

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u/dario_vermeulen33 points·2 years ago

This is the correct framing. The COA structure matters as much as the number.

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u/soren_nkemelu17 points·2 years ago

PDF metadata is checkable in fifteen seconds

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u/wanjiru_varga5 points·2 years ago·edited

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

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u/purity_pedantanalytical12 points·2 years ago

PDF metadata is checkable in fifteen seconds

Disagree on that part. 97.9% and 97.6% on the same vial is normal.

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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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  1. Post the full document. Cropped COAs that hide the batch number or date get removed.
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