From the other side of the consultation, briefly.
Vendor quality matters when discussing certificates of analysis. I've tested my last 3 batches through Janoshik and purity has ranged from 98.8% to 99.0%. Consistency is key.
For anyone new: always request the COA, and consider independent verification. The $300 for a Janoshik test is worth the peace of mind.
Dr.Martinez said:Vendor quality matters when discussing certificates of analysis.
This is my experience too, for whatever a second data point is worth.
Dr.Martinez said:Vendor quality matters when discussing certificates of analysis.
Third-party testing services for certificates of analysis besides Janoshik:
- Janoshik: Gold standard for peptide community, ~$133, 10-14 day turnaround
- Valitech: US-based, ISO 17025 accredited, ~$243
- Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
- ChemTox: Basic identity and purity testing, ~$103
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.
Sigma-Aldrich — Research-Grade Standards
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference StandardsDr.Martinez said:Vendor quality matters when discussing certificates of analysis.
I tested my certificates of analysis batch through Janoshik — 98.4% purity. That's within acceptable range for compounded peptides. Turnaround was 8 business days.
The test costs ~$133 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 Dr.Martinez — and this may be the naive question:
Whether a purity figure and a content figure can disagree without one of them being wrong?