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

why does nobody talk about related substances

COA Well Actually ×3

Right, the certificate of analysis question again, but with numbers this time.

I have 9 data points over 14 weeks. The pattern is consistent enough that I do not think it is chance, and boring enough that nobody is going to screenshot it, which is usually a good sign.

The thing I would flag for anyone new: the effect I am describing showed up at week 49, not week 3. People give up long before the interesting part.

Interested in whether this matches other people's logs or whether I am an outlier.

890 up / 261 down77% upvoted27 commentsid 10fiw114 Dec 2024

27 comments

22 in this archive, depth 5

best — the order this archive was captured in

u/soren_nkemelu54 points·1 year ago
appreciate you saying you do not know
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u/sig_figs_samOPmod · analytical22 points·1 year ago

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

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u/dario_vermeulen0 points·1 year ago

area% is not mass%, and here is exactly why it matters

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u/cormac_pereira28 points·1 year ago

Cosigning. The batch number is load-bearing information.

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u/sig_figs_samOPmod · analytical14 points·1 year ago

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

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u/amira_dumitru20 points·1 year ago

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

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[deleted]8 points·1 year ago

[deleted]

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u/alcohol_aversion9 points·1 year ago

Slight fix: the number was 96.2, not 96.8. Decimal point, but a fairly consequential one.

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u/purity_pedantMOD15 points·1 year ago

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

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u/marisol_frisk4 points·1 year ago

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

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u/liv_nkemelu1 point·1 year ago

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

Disagree on that part. 93.7% and 99.3% on the same vial is normal.

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u/cato_achebe5 points·1 year ago

Metadata check caught a COA that was created in a browser four months after the analysis date. Not evidence of fraud, but worth flagging to QYB.

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u/purity_pedantanalytical11 points·1 year ago

The evidence standard in c/vendorvetting gets called too strict about once a month, and every time, the thread ends with the complainant agreeing.

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u/bastian_aalto5 points·1 year ago

area% is not mass%, and here is exactly why it matters

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u/sofia_ferreira1 point·1 year ago

area% is not mass%, and here is exactly why it matters

Yes, exactly this, and it is the bit that took me 88 weeks to accept.

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u/milos_trevino-29 points·1 year ago

Cosigning. The batch number is load-bearing information.

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u/janek_ferrari7 points·1 year ago

What were the related substances listed individually?

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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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