Endotoxin testing methods — what worked for you?

Dr.SportsMedIN said:

They are not contradictory, they measure different things, and this is the single most common misreading of a certificate.

Bookmarking. The distinction being drawn above is the one nobody else makes. I will report back once I have actually tried it.

Clinical perspective, offered as context rather than as advice.

COA red flags for certificates of analysis — here's what to look for when reviewing a Certificate of Analysis:

• No HPLC data: If there's no chromatography graph, it's not a real COA
• Exact 100% purity: Suspicious — real testing always shows slight variation
• No batch number: Can't trace back to specific production
• No endotoxin testing: For injectables, this is essential
• Template looks like it was made in Word: Professional labs have standardized formats

I have seen fake COAs that are literally photoshopped. Always verify independently if possible.

pat_auckland said:

I tested my certificates of analysis batch through Janoshik — 97.6% purity.

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: 99.5% purity, 0.3% total related substances. Clean chromatogram with single sharp peak at expected retention time. Exactly what you want to see.

kevin_tulsa said:

The provenance questions are more useful than the numbers.

My vendor review relevant to certificates of analysis: ordered 4 times from my current compounder. Consistency has been excellent.

Shipping: 2-day priority with gel ice
Packaging: Professional, discreet, proper labeling with lot/batch numbers
Purity: 98.5% average across orders (Janoshik verified)
Customer service: Responsive within 4 hours
Price: $125/month for tirzepatide 10mg equivalent

Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful. Report rather than reply if it drifts again.