Subject: Peptidology Just Upgraded Their Testing Standard and Their Discount
From: Derek from Peptide Price <[email-masked]>
To: [email-masked]
Date: Wed, 8 Apr 2026 16:15:30 +0000
List-Id: <derekpruski.substack.com>

View this post on the web at https://derekpruski.substack.com/p/peptidology-just-upgraded-their-testing

Peptidology Just Upgraded Their Testing Standard + 25% Off Sale
Got a message with some details worth sharing. Peptidology has a large inventory, and it’s worth being transparent about where things stand — some products in their catalog currently only have 2x sterility testing. But 19 compounds have already been brought up to a standard, and all new products going forward will be tested to an even higher one.
Research use only, not for human consumption.
Before I get into it — they’re running 25% off sitewide right now with code DEREK25.
Shop here: https://peptidology.co/?ref=mxxyvdne [ https://substack.com/redirect/c452e81e-4b97-4e07-ad6e-d2ba8c6a8fce?j=eyJ1IjoiNGl3b2U2In0.sVDxRtmZ85v8kfdamY0krRXGMy3p768BWtuZifRB-Zs ]
Here’s what that looks like, and what each test actually means.
Current Standard — 19 Compounds Already Tested
3x Purity/Quantity
2x USP <85> Endotoxins
1x ICP-MS Heavy Metals
2x Container Closure Integrity
1x Residual Solvents + TFA
2x Particulate Analysis/Solubility
5x USP <71> Sterility (Vanguard)
4x USP <71> Sterility (Eagle)
New Standard — All New Products Going Forward
3x Purity/Quantity
3x USP <85> Endotoxins
2x ICP-MS Heavy Metals
3x Container Closure Integrity
1x Residual Solvents + TFA
3x Particulate Analysis/Solubility
5x USP <71> Sterility (Vanguard)
15x USP <71> Sterility (Eagle)
What Each Test Actually Means
Purity/Quantity (HPLC) This is the most fundamental test. It uses a method called HPLC (High Performance Liquid Chromatography) to confirm two things: that the compound in the vial is actually what it’s labeled as, and that the amount matches what’s on the label. If a vendor only runs one test, this is usually it. Testing 3 vials per batch instead of 1 gives a more accurate picture across the production run.
USP <85> Endotoxins (LAL Test) Endotoxins are toxic fragments from the outer wall of certain bacteria. The tricky part is that the bacteria don’t need to be alive to cause a problem — the toxin itself remains even after the bacteria are dead, and a standard sterility test won’t catch it. USP <85> uses the LAL (Limulus Amebocyte Lysate) method, which is specifically designed to detect endotoxins. Results are measured in EU/mg and compared against USP/FDA thresholds. This is a test a lot of vendors skip entirely.
ICP-MS Heavy Metals ICP-MS (Inductively Coupled Plasma Mass Spectrometry) screens for toxic heavy metals: lead, arsenic, cadmium, mercury, and chromium. These can enter a product through the raw materials used in synthesis or through manufacturing equipment. You won’t taste or see them, and they won’t show up on a purity test — which is why a dedicated heavy metals test matters.
Container Closure Integrity This test confirms the vial is actually sealed properly using a dye ingress method — a dye solution is applied around the sealed vial under pressure, and the vial is then checked to see if any dye got inside. A compromised seal allows bacteria, moisture, or air to enter the vial after it leaves the facility, which can contaminate an otherwise clean product.
Residual Solvents + TFA Solvents like acetone, methanol, benzene, and dichloromethane are used during peptide synthesis and need to be fully removed from the final product. TFA (trifluoroacetic acid) is another common byproduct of the synthesis process that needs to be washed out — residual TFA can affect the stability of the peptide and cause issues if present in meaningful amounts. This test screens for all of them via GC-MS and ion chromatography.
Particulate Analysis / Solubility This test confirms the peptide fully dissolves when reconstituted and that no visible or subvisible particles are present in solution. A peptide that clumps, clouds, or won’t dissolve cleanly is a red flag for degradation or poor manufacturing. This is the practical test for what you’d actually see when you reconstitute a vial.
USP <71> Sterility — Vanguard USP <71> is the gold standard sterility test in pharmaceutical manufacturing. Samples are placed in growth media and incubated for 14 days. If anything grows — bacteria, fungi, mold — it’s a fail. Testing 5 vials at an ISO 17025-accredited lab like Vanguard gives a statistically meaningful result across the batch.
USP <71> Sterility — Eagle Analytical The same sterility test run at a completely separate, independent accredited lab. Eagle uses the ScanRDI method, a rapid microbial detection system that can identify contamination faster than traditional incubation. Running sterility at two independent labs, something no one else in the space is doing right now. The upgrade from 4 to 15 samples at Eagle is the biggest single jump in the new standard — 15 vials across two labs means a much higher level of confidence in the result.
Most vendors in this space run a purity test and maybe a single sterility check. What Peptidology is committing to here — across 19 products already and as the standard for everything new — is well above what I typically see on COAs coming through PeptidePrice.store [ https://substack.com/redirect/2b15f142-f17b-48aa-a6e6-132c7c6638f1?j=eyJ1IjoiNGl3b2U2In0.sVDxRtmZ85v8kfdamY0krRXGMy3p768BWtuZifRB-Zs ].
They’re also running 25% off sitewide right now with code DEREK25.
Shop Peptidology: 
https://peptidology.co/?ref=mxxyvdne [ https://substack.com/redirect/c452e81e-4b97-4e07-ad6e-d2ba8c6a8fce?j=eyJ1IjoiNGl3b2U2In0.sVDxRtmZ85v8kfdamY0krRXGMy3p768BWtuZifRB-Zs ]
Compare prices: peptideprice.store [ https://substack.com/redirect/2b15f142-f17b-48aa-a6e6-132c7c6638f1?j=eyJ1IjoiNGl3b2U2In0.sVDxRtmZ85v8kfdamY0krRXGMy3p768BWtuZifRB-Zs ]
For research use only. Not for human consumption.

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