Endotoxin testing methods — what worked for you?

pat_auckland said:

The provenance questions are more useful than the numbers.

That reframing is the part I needed.

From the other side of the consultation, briefly.

Third-party testing services for certificates of analysis besides Janoshik:

• Janoshik: Gold standard for peptide community, ~$132, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$212
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$112

Janoshik is the community standard but any ISO-accredited analytical lab can verify peptide identity and purity. The key is independence — don't rely solely on the vendor's own testing.

BariatricNurseD 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:…

Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members. Across 61 submitted tests:

• 78% tested at ≥98% purity
• 15% 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.

Dr.KarenChen said:

Inter-laboratory variation comes from real methodological differences, not sloppiness: which reference standard was used and how it was itself…

My vendor review relevant to certificates of analysis: ordered 5 times from my current compounder. Consistency has been excellent.

Shipping: Same-day local pickup
Packaging: Professional, discreet, proper labeling with lot/batch numbers
Purity: 97.2% average across orders (Janoshik verified)
Customer service: Responsive within 6 hours
Price: $130/month for semaglutide 2.4mg equivalent

Moderator note: the sourcing question belongs in the vendor section and has been split out.