LC-MS/MS vs HPLC for peptide analysis — November 2025

Dr.SportsMedIN said:

Third-party testing services for certificates of analysis besides Janoshik: Janoshik: Gold standard for peptide community, ~$141, 10-14 day turnaround…

Vendor quality matters when discussing certificates of analysis. I've tested my last 4 batches through Janoshik and purity has ranged from 98.7% to 100.5%. 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.

One concrete data point for the thread. Practical: whatever you change, write down the date and the reason. In three months the reason is what you will have forgotten, and the reason is what makes the record worth having.

One thing that is still open after Dr.SportsMedIN’s answer:

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

DoseLogDan said:

Practical: whatever you change, write down the date and the reason.

This is where I part company with the consensus forming above. Pushing back on the consensus forming here. Consistency is not the same as correctness, and a board that agrees with itself quickly is usually agreeing with the first person who sounded certain.

DoseLogDan said:

Practical: whatever you change, write down the date and the reason.

Agreed, and the size of the effect matters as much as its existence. Something real and small gets treated here as though it were real and decisive.