GLPHubglpresearchhub.com
Read-only archive. GLP Research Hub is a static community record — nothing here is for sale, no account is needed, and no vote you cast is counted. Why?
Single comment threadYou are looking at one branch of how much of what we believe about COA actually comes from area percent threads — 58 comments in the full submission. View in context.
1.8k
c/coa·submitted 2 years ago by u/emil_agyeman

how much of what we believe about COA actually comes from area percent threads

Suspiciousbranch of 10 comments

Genuine question, and the title is the question: how much of what we believe about COA actually comes from area percent threads. 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. Asked for the storage condition behind the stability…

Read the full submission and all 58 comments →

This branch

10 comments, started 2 years ago
u/zeynep_zielinski49 points·2 years ago

What does the method line actually say? Not the technique — the column and the gradient.

replysharereportpermalink
u/emil_agyemanOP35 points·2 years ago

Did you get the chromatogram or only the summary line?

replysharereportpermalink
u/aurel_boateng30 points·2 years ago

Sent one vial to Janoshik and Medutest. 97.9% and a claimed 97.0%. Cost me more than the vial and I would do it again.

replysharereportpermalink
u/emil_agyeman37 points·2 years ago·edited

Sent one vial to Janoshik and Medutest.

aurel_boateng has the distinction right — one is a fraction of the detector signal, the other is a fraction of the mass.

replysharereportpermalink
u/fatima_wojcik24 points·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.

replysharereportpermalink
u/aurel_boateng18 points·2 years ago·edited

Agreed on asking for the storage condition. It is one line and it changes how you read the entire stability claim.

replysharereportpermalink
u/zeynep_zielinski8 points·2 years ago

the counterion is part of the mass you paid for

replysharereportpermalink
u/rohan_steiner4 points·2 years ago

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

replysharereportpermalink
u/bastian_moreau5 points·2 years ago

Yes. The structure of the document matters at least as much as the number printed on it.

replysharereportpermalink
u/nadia_kjaer20 points·2 years 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.

replysharereportpermalink

← back to the whole thread

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.

71kmembers
130submissions
Aug 2023created
submissions / month, last year
Sponsored

Janoshik Analytical

Independent HPLC and mass spec. The number you get is the number they found.

janoshik.com
Sponsored

GL Biochem (Shanghai)

Custom peptides and amino acids direct from the manufacturer since 1998. ISO 9001 / cGMP. Batch COA every order.

glbiochem.net
c/coa rules
  1. Post the full document. Cropped COAs that hide the batch number or date get removed.
  2. Redact your own name and order id, not the vendor's batch details.
  3. No "is this good?" without saying what the compound and claimed purity are.
  4. Independent community. Nobody here sells anything, and anyone who tries is banned.
  5. Not medical advice. Describe what you did; never prescribe to a stranger.
  6. Claims need evidence. Batch numbers, dated screenshots, independent test reports, or a citation.
  7. No referral links, discount codes or affiliate URLs. Permanent ban, no appeal.
  8. No contact handles, wallet addresses or tracking numbers — they identify people.
  9. Be recognisably decent. Disagree hard, insult nobody.
Moderators
Volunteers. Unpaid, unaffiliated, and reachable through modmail only.
Before you read on

Several compounds discussed on GLP Research Hub are sold for research use only and are not approved for human use anywhere. Nothing here is medical advice and none of it is written by your clinician. If a post reads like an instruction, treat it as a description of what one stranger did.