amsterdam_pete said:They are not contradictory, they measure different things, and this is the single most common misreading of a certificate.
My vendor review relevant to certificates of analysis: ordered 6 times from my current compounder. Consistency has been excellent.
Shipping: 3-day with temperature monitor
Packaging: Professional, discreet, proper labeling with lot/batch numbers
Purity: 98.3% average across orders (Janoshik verified)
Customer service: Responsive within 1 hours
Price: $155/month for tirzepatide 10mg equivalent
Following on from jim_asheville — and this may be the naive question:
Whether a purity figure and a content figure can disagree without one of them being wrong?
PeptideSynthNJ said:My vendor review relevant to certificates of analysis: ordered 6 times from my current compounder.
Third-party testing services for certificates of analysis besides Janoshik:
- Janoshik: Gold standard for peptide community, ~$138, 10-14 day turnaround
- Valitech: US-based, ISO 17025 accredited, ~$228
- Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
- ChemTox: Basic identity and purity testing, ~$108
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.
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Purity and content being different measurements was the piece I was missing. The vial was overfilled and pure, which is a very different problem from the one I thought I had.
newstart_MO said:Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$138, 10-14 day turnaround…
That is correct as far as it goes, and here is where it stops going. One addition: an unstated method makes a report close to uninterpretable. "99% pure" without the technique, the standard and the conditions is a claim, not a measurement.