Has anyone dealt with moisture content analysis for lyophilized peptides?

TrialNerd_Beth said:

My HPLC chromatogram analysis for certificates of analysis — I sent my batch to Janoshik and here's what the results showed: Main peak retention time:…

I tested my certificates of analysis batch through Janoshik — 97.6% purity. That's within acceptable range for compounded peptides. Turnaround was 10 business days.

The test costs ~$120 but gives you actual HPLC chromatography data plus mass spec confirmation. For the peace of mind alone, it's worth every penny. I test every new batch from a new vendor.

Following on from TrialNerd_Beth — and this may be the naive question:

Did your prescriber agree with that reading, and if not what was their objection?

PeptideChemSF said:

I tested my certificates of analysis batch through Janoshik — 97.6% purity.

Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members. Across 47 submitted tests:

• 75% tested at ≥98% purity
• 18% tested at 95-98% purity
• 7% tested at <95% purity (concerning)

The vendors with consistently high purity results are listed in the Vendor Directory. We update monthly based on new community submissions.

PeptideChemSF said:

I tested my certificates of analysis batch through Janoshik — 97.6% purity.

Right, and the exception is worth naming rather than left implied, because the exception is where people get into trouble.

PeptideChemSF said:

I tested my certificates of analysis batch through Janoshik — 97.6% purity.

This is exactly what I could not find anywhere else.