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Evidence-based GLP-1 & peptide discussion since 2023
ForumsCOA & Analytical TestingBatch-to-batch purity variation — acceptable ranges Page 2

Batch-to-batch purity variation — acceptable ranges

kate.chem Wed, Mar 11, 2026 at 4:15 AM 15 replies 505 viewsPage 2 of 3
hank_denver
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278
1,234
Sep 2024
Denver, CO
Mar 11, 2026 at 7:05 AM#6

Don't panic. Low purity primarily means you're getting less active ingredient than you think, so your dose is effectively lower. The degradation products in peptides are usually not toxic — they're typically inactive fragments. But "usually" isn't "always," and without characterization of those impurities, we can't say for certain.

The bigger concern is what it says about the pharmacy's quality systems. If they're releasing product at 82% but labeling 98%, either their testing is inaccurate or they're falsifying COAs. Neither is acceptable.

7 1ingrid_STO, pete_nash, hank_denver and 4 others
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Dr.LeslieOBGYN
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567
2,567
May 2024
Dallas, TX
Mar 11, 2026 at 7:22 AM#7

UPDATE: I called the pharmacy. They were initially defensive but eventually agreed to test the retained sample. They said results would take "5-7 business days." I also filed a complaint with my state board of pharmacy.

I'm switching to a 503B facility. Already got a new script from my doctor. This experience has been eye-opening. I'll post the retained sample results when I get them.

For anyone reading this — TEST YOUR STUFF. Janoshik was $120 well spent. 💯

Last edited: Mar 11, 2026 at 1:22 PM
25 12FranDenver, Dr.BariatricHTX, LindaRN_retired and 22 others
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nick_SD_fit
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Sep 2024
San Diego, CA
Mar 11, 2026 at 7:39 AM#8

Thanks for sharing this Dave. This is exactly the kind of data-driven community reporting that helps everyone. Tagged this thread as [QUALITY ALERT]. Please do update us with the retained sample results.

48 16EndoResFellow, PharmacoVig_BOS, SurmountFan_IN and 45 others
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oliver_london
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312
1,345
Aug 2024
London, UK
Mar 11, 2026 at 7:56 AM#9

FINAL UPDATE: Pharmacy came back and said their retained sample tested at 96.8%. They're claiming the discrepancy is due to "shipping conditions." I'm not buying it — I shipped with cold packs and Janoshik confirmed the sample arrived cold. I've moved on to a different pharmacy and sent THAT vial to Janoshik too. Will report back. At this point I'm basically funding Janoshik's retirement. 😂

47 23jason_paloalto, Dr.LeslieOBGYN, MikeNYC_runner and 44 others
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