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

Clinical perspective, offered as context rather than as advice.

HPLC results interpretation for certificates of analysis: when you get your Janoshik report back, here's what the numbers mean:

• Purity %: Should be >97%. Below 95% is concerning.
• Retention time: Should match reference standard for the peptide
• Related substances: Degradation products should be <2% total
• Single impurity: No individual impurity should exceed 1%

My last batch: 99.2% purity, 0.2% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.

HPLC_Greg said:

I tested my certificates of analysis batch through Janoshik — 98.1% purity.

Community-verified vendors for certificates of analysis: I maintain a spreadsheet of Janoshik-verified test results submitted by community members. Across 54 submitted tests:

• 82% tested at ≥98% purity
• 12% tested at 95-98% purity
• 6% 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.

HPLC_Greg said:

I tested my certificates of analysis batch through Janoshik — 98.1% purity.

Bookmarking. The distinction being drawn above is the one nobody else makes. Sending this to two other people who asked me the same thing last week.

Adding the clinical framing, because it changes how the question reads.

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

• Janoshik: Gold standard for peptide community, ~$141, 10-14 day turnaround
• Valitech: US-based, ISO 17025 accredited, ~$211
• Eurofins: Full pharmaceutical testing suite, more expensive but comprehensive
• ChemTox: Basic identity and purity testing, ~$101

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.

Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful. No action needed from anybody.