Return-Path: Received: from [2607:fb90:e204:5c1f:60b8:5c09:100:0] ([2607:fb90:e204:5c1f:1145:fbcb:a4b8:72b]) by smtp.gmail.com with ESMTPSA id 00721157ae682-79b1e41e735sm14487417b3.45.2026.03.26.08.39.55 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Mar 2026 08:39:56 -0700 (PDT) Date: Thu, 26 Mar 2026 11:39:40 -0400 From: tjphuhs@gmail.com To: "=?utf-8?Q?oc.tjphuhs=40gmail.com?=" Message-ID: <46224b40-c8bb-4d34-8c91-81d0e70c3980@Spark> In-Reply-To: <20260326124921.3.cef546f1d4953f68@mg-d0.substack.com> References: <20260326124921.3.cef546f1d4953f68@mg-d0.substack.com> Subject: Fwd: The Test That's Actually Failing - 3 of 6 Failed Sterility at 99.8% X-Readdle-Message-ID: 46224b40-c8bb-4d34-8c91-81d0e70c3980@Spark MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="69c5534b_77fc9051_733a" --69c5534b_77fc9051_733a Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline ---------- =46orwarded message ---------- =46rom: Derek from Peptide Price Date: Mar 26, 2026 at 8:49=E2=80=AFAM -0400 To: tjphuhs=40gmail.com Subject: The Test That's Actually =46ailing - 3 of 6 =46ailed Sterility a= t 99.8% > Yesterday I ran a poll asking which test you=E2=80=99d add on top of id= entification, purity, and net content. > =CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0= =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2= =AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2= =A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87= =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F= =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80= =87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD= =8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2= =80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD= =CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0= =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2= =AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2= =A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87= =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F= =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80= =87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD= =8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2= =80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD= =CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0= =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2= =AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2= =A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87= =C2=AD=CD=8F 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=C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD= =CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0= =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2= =AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2= =A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87= =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F= =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80= =87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD= =8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2= =80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD= =CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0= =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2= =AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2= =A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87= =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F= =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80= =87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD= =8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2= =80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD= =CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0= =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2= =AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2= =A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87= =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F= =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80= =87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD= =8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2= =80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD= =CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0= =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2= =AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2= =A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87= =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F= =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80= =87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD= =8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2= =80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD= =CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0= =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2= =AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2= =A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87= =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F= =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80= =87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD= =8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2= =80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD= =CD=8F =C2=A0 =E2=80=87 =C2=AD=CD=8F =C2=A0 =E2=80=87 =C2=AD > =46orwarded this email=3F Subscribe here for more > The Test That's Actually =46ailing - 3 of 6 =46ailed Sterility at 99.8%= > Derek > Mar 26 > > READ IN APP > > Yesterday I ran a poll asking which test you=E2=80=99d add on top of id= entification, purity, and net content. > 127 votes came in: > > =E2=80=A2 > Endotoxins =E2=80=94 55 votes (43%) > =E2=80=A2 > Sterility =E2=80=94 50 votes (39%) > =E2=80=A2 > Heavy Metals =E2=80=94 22 votes (17%) > > Endotoxins won. And honestly, that=E2=80=99s a reasonable choice =E2=80= =94 endotoxins are well understood, they have clear pass/fail thresholds,= and they=E2=80=99re directly relevant to safety. > But here=E2=80=99s what the real-world data is actually showing: steril= ity is the test that=E2=80=99s failing more than anything else across ven= dors right now. > Not at alarming rates. But it=E2=80=99s happening =E2=80=94 and it=E2=80= =99s happening on batches where everything else looks perfect. > Peptidology just shared their MOTS-C COA with me (Lot 1670), and it=E2=80= =99s a textbook example of exactly this. Let=E2=80=99s walk through it. > Everything else on this batch passed cleanly. > Vanguard Laboratory ran a comprehensive panel on 2/26/2026: > > =E2=80=A2 > Chromatographic purity (HPLC-UV/VIS): >99.80% across all th= ree vials tested > =E2=80=A2 > Assay/net content: 10.36 mg, 10.32 mg, 10.36 mg =E2=80=94 l= abeled at 10 mg, so slight overfill, which is normal and good > =E2=80=A2 > Heavy metals (ICP-MS): chromium, arsenic, cadmium, lead, an= d mercury all non-detect > =E2=80=A2 > Endotoxins (LAL): both samples passed at <5.00 EU/mg, well = under the USP/=46DA threshold > =E2=80=A2 > Residual solvents (GC-MS): all 16 solvents tested =E2=80=94= benzene, chloroform, dichloromethane, acetone, ethanol, and more =E2=80=94= all non-detect > =E2=80=A2 > T=46A: non-detect, below 0.10% > =E2=80=A2 > Solubility: fully soluble in 2 mL water on both samples tes= ted > =E2=80=A2 > Container closure integrity (dye ingress): both passed > > On paper, this is as clean as a COA gets. > Then you get to sterility. > Vanguard ran USP <71> sterility testing on five samples from this lot. = Three failed =E2=80=94 growth detected. Two passed =E2=80=94 no growth. > Eagle Analytical Services ran an independent ScanRDI sterility test on = a separate sample from the same lot. That one passed. > Six total sterility tests across two independent labs. Three fail, thre= e pass. Same lot. Same batch. > This is not a vendor failure. This is sterility testing doing exactly w= hat it=E2=80=99s supposed to do =E2=80=94 and showing you how complicated= this actually is. > Why can samples from the same lot give different sterility results=3F > Sterility isn=E2=80=99t a property of the compound itself. MOTS-C doesn= =E2=80=99t inherently have bacteria in it. What sterility testing is dete= cting is contamination =E2=80=94 and contamination is not uniform. > Think of it like this: if you dropped a single grain of dirt into a swi= mming pool, some water samples would test positive and some would test ne= gative depending on where you pulled from. The contamination exists somew= here, but it=E2=80=99s not evenly distributed. > A few mechanisms that explain variable results on the same lot: > 1. Environmental contamination during fill/finish The peptide compound = itself may be clean. But the process of filling vials and lyophilizing (f= reeze-drying) happens in a controlled environment =E2=80=94 and that envi= ronment isn=E2=80=99t always perfect. A brief lapse in cleanroom conditio= ns, a failure of laminar flow, an unsterilized surface =E2=80=94 any of t= hese can introduce contamination into some vials but not others. > 2. Low-level contamination below detection threshold The contamination = load may be very low =E2=80=94 a small number of organisms. If only a han= dful of bacteria are present, the test may detect it in some samples and = miss it in others depending on exact volume tested and starting organism = count. > 3. Two different methods were used here The Vanguard results used USP <= 71> =E2=80=94 a culture-based method that incubates samples for 14 days t= o see if anything grows. Eagle used ScanRDI, which stains and filters the= sample and counts organisms directly under fluorescent light in roughly = 24 hours. These two methods can give different results on borderline samp= les. Neither is wrong =E2=80=94 they=E2=80=99re measuring slightly differ= ent things with different sensitivities. > 4. Sampling variability =46or a 10 mg vial, the tested portion is a fra= ction of total content. If contamination is localized to a specific area = of the vial, some draws will capture it and others won=E2=80=99t. > What does this mean for researchers=3F > A few takeaways: > A single sterility pass doesn=E2=80=99t guarantee the entire lot is ste= rile. This is why testing multiple samples and using independent labs mat= ters. Peptidology sent samples to two different labs =E2=80=94 that=E2=80= =99s the right approach. > Purity >99% tells you nothing about sterility. These are completely sep= arate things. A peptide can be analytically perfect and still have microb= ial contamination introduced during manufacturing. The argument =E2=80=9C= if purity is high, everything else is fine=E2=80=9D doesn=E2=80=99t hold.= > Sterility failures don=E2=80=99t automatically mean a vendor has bad pr= actices. It means contamination is hard to eliminate entirely and even ha= rder to detect consistently. What matters is whether the vendor is testin= g at all, how many samples they=E2=80=99re running, and what they do when= failures show up. > Endotoxins and sterility are not the same test. Endotoxins (LAL) detect= fragments from gram-negative bacterial cell walls =E2=80=94 they can be = present even if all live organisms are dead or removed. Both tests matter= independently, and both passed on this COA. > The bottom line > You voted endotoxins as the most important additional test. That=E2=80=99= s not wrong =E2=80=94 endotoxins are important and worth testing for. > But if you=E2=80=99re looking at what=E2=80=99s actually coming back wi= th failures on otherwise clean product right now, sterility is making the= strongest case for itself. > Peptidology sharing this data publicly =E2=80=94 including the failures= =E2=80=94 is exactly the kind of transparency the research community sho= uld be pushing vendors for. The uncomfortable results matter more than th= e clean ones. > All compounds referenced are for research purposes only, not for human = consumption. > Upgrade to paid > You're currently a free subscriber to Peptide Price. =46or the full exp= erience, upgrade your subscription. > Upgrade to paid > > Share > > > Like > Comment > Restack > > =C2=A9 2026 Derek Pruski > 548 Market Street PMB 72296, San =46rancisco, CA 94104 > Unsubscribe --69c5534b_77fc9051_733a Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
---------- =46orwarded message ----= ------
=46rom: Derek from Peptide Price <derekpruski=40substack.com>= ;
Date: Mar 26, 2026 at 8:49=E2=80=AFAM -0400
To: tjphuhs=40gmail.com
Subject: The Test That's Actually =46ailing - 3 of 6 =46ailed Ster= ility at 99.8%

3D=22=22
Yesterday I ran a poll asking which test you=E2=80=99d add on to= p of identification, purity, and net content.
=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23= 160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80= =87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD= =CD=8F &=23160; =E2=80=87 =C2=AD=CD=8F &=23160; =E2=80=87 =C2=AD
=46orwarded this email=3F Subscribe here for more=

The Test That's Actually =46ailing - 3 of 6 =46ailed Sterility at 99.8%<= /a>

Derek
&=23160;=
3D=22=22
3D=22=22
3D=22=22
3D=22=22
READ IN APP3D=
&=23160;=

Yesterday I ran a poll asking wh= ich test you=E2=80=99d add on top of identification, purity, and net cont= ent.

127 votes came in:

  • Endot= oxins =E2=80=94 55 votes (43%)

  • Steri= lity =E2=80=94 50 votes (39%)

  • Heavy= Metals =E2=80=94 22 votes (17%)

Endotoxins won. And honestly, that=E2=80=99s a reasona= ble choice =E2=80=94 endotoxins are well understood, they have clear pass= /fail thresholds, and they=E2=80=99re directly relevant to safety.

But here=E2=80=99s what the real-world data is a= ctually showing: sterility is the test that=E2=80=99s fail= ing more than anything else across vendors right now.

Not at alarming rates. But it=E2=80=99s happening =E2=80= =94 and it=E2=80=99s happening on batches where everything else looks per= fect.

Peptidology just shared their MOTS-C COA with me (Lot = 1670), and it=E2=80=99s a textbook example of exactly this. Let=E2=80=99s= walk through it.

Everything else on this batch passed cleanly.<= /strong>

Vanguard Laboratory ran a comprehensive panel on 2/26/= 2026:

  • Chrom= atographic purity (HPLC-UV/VIS): >99.80% across all three vials tested=

  • Assay= /net content: 10.36 mg, 10.32 mg, 10.36 mg =E2=80=94 labeled at 10 mg, so= slight overfill, which is normal and good

  • Heavy= metals (ICP-MS): chromium, arsenic, cadmium, lead, and mercury all non-d= etect

  • Endot= oxins (LAL): both samples passed at <5.00 EU/mg, well under the USP/=46= DA threshold

  • Resid= ual solvents (GC-MS): all 16 solvents tested =E2=80=94 benzene, chlorofor= m, dichloromethane, acetone, ethanol, and more =E2=80=94 all non-detect

  • T=46A= : non-detect, below 0.10%

  • Solub= ility: fully soluble in 2 mL water on both samples tested

  • Conta= iner closure integrity (dye ingress): both passed

On paper, this is as clean as a COA gets.

3D=22image.png=22
3D=22image.png=22
3D=22image.png=22

Then you get to sterility.

Vanguard ran USP <71> sterility testing on five = samples from this lot. Three failed =E2=80=94 growth detected. Two passed= =E2=80=94 no growth.

Eagle Analytical Services ran an independent ScanRDI s= terility test on a separate sample from the same lot. That one passed.

Six total sterility tests across two independent= labs. Three fail, three pass. Same lot. Same batch.

This is not a vendor failure. This is sterility testin= g doing exactly what it=E2=80=99s supposed to do =E2=80=94 and showing yo= u how complicated this actually is.

Why can samples from the same lot give differe= nt sterility results=3F

Sterility isn=E2=80=99t a property of the compound its= elf. MOTS-C doesn=E2=80=99t inherently have bacteria in it. What sterilit= y testing is detecting is contamination =E2=80=94 and contamination is no= t uniform.

Think of it like this: if you dropped a single grain o= f dirt into a swimming pool, some water samples would test positive and s= ome would test negative depending on where you pulled from. The contamina= tion exists somewhere, but it=E2=80=99s not evenly distributed.

A few mechanisms that explain variable results on the = same lot:

1. Environmental contamination during fill/fin= ish The peptide compound itself may be clean. But the proc= ess of filling vials and lyophilizing (freeze-drying) happens in a contro= lled environment =E2=80=94 and that environment isn=E2=80=99t always perf= ect. A brief lapse in cleanroom conditions, a failure of laminar flow, an= unsterilized surface =E2=80=94 any of these can introduce contamination = into some vials but not others.

2. Low-level contamination below detection thr= eshold The contamination load may be very low =E2=80=94 a = small number of organisms. If only a handful of bacteria are present, the= test may detect it in some samples and miss it in others depending on ex= act volume tested and starting organism count.

3. Two different methods were used here The Vanguard results used USP <71> =E2=80=94 a culture-bas= ed method that incubates samples for 14 days to see if anything grows. Ea= gle used ScanRDI, which stains and filters the sample and counts organism= s directly under fluorescent light in roughly 24 hours. These two methods= can give different results on borderline samples. Neither is wrong =E2=80= =94 they=E2=80=99re measuring slightly different things with different se= nsitivities.

4. Sampling variability =46or a= 10 mg vial, the tested portion is a fraction of total content. If contam= ination is localized to a specific area of the vial, some draws will capt= ure it and others won=E2=80=99t.

What does this mean for researchers=3F

A few takeaways:

A single sterility pass doesn=E2=80=99t guarantee the = entire lot is sterile. This is why testing multiple samples and using ind= ependent labs matters. Peptidology sent samples to two different labs =E2= =80=94 that=E2=80=99s the right approach.

Purity >99% tells you nothing about sterility. Thes= e are completely separate things. A peptide can be analytically perfect a= nd still have microbial contamination introduced during manufacturing. Th= e argument =E2=80=9Cif purity is high, everything else is fine=E2=80=9D d= oesn=E2=80=99t hold.

Sterility failures don=E2=80=99t automatically mean a = vendor has bad practices. It means contamination is hard to eliminate ent= irely and even harder to detect consistently. What matters is whether the= vendor is testing at all, how many samples they=E2=80=99re running, and = what they do when failures show up.

Endotoxins and sterility are not the same test. Endoto= xins (LAL) detect fragments from gram-negative bacterial cell walls =E2=80= =94 they can be present even if all live organisms are dead or removed. B= oth tests matter independently, and both passed on this COA.

The bottom line

You voted endotoxins as the most important additional = test. That=E2=80=99s not wrong =E2=80=94 endotoxins are important and wor= th testing for.

But if you=E2=80=99re looking at what=E2=80=99s actual= ly coming back with failures on otherwise clean product right now, steril= ity is making the strongest case for itself.

Peptidology sharing this data publicly =E2=80=94 inclu= ding the failures =E2=80=94 is exactly the kind of transparency the resea= rch community should be pushing vendors for. The uncomfortable results ma= tter more than the clean ones.

All compounds referenced are for research purposes= only, not for human consumption.

Upgrade to paid=

You're= currently a free subscriber to Peptide Price. =46or the full experience, upgrade your subscription.

Upgra= de to paid

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=C2=A9 2026 Derek Pruski
548 Market Street PMB 72296, San =46rancisco, CA 94104
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