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Quality & testing

We publish the proof, not the promise.

A purity claim is a sentence; a chromatogram is evidence. Every Peptide Labs production lot passes six independent testing layers at an accredited third-party US laboratory before a single vial ships — and the full results travel in the box with your order.

The release panel

Six layers between synthesis and shipment

Each layer answers a different question — how pure, which molecule, how clean, how much. A lot must clear all six to leave quarantine.

01

HPLC Purity — ≥99%

Each lot is run on reversed-phase HPLC (C18, water/acetonitrile gradient with 0.1% TFA) with UV detection at 214 nm, where the peptide bond absorbs. Purity is reported as main-peak area percent against total integrated area. Anything below 99.0% — or any single related-substance peak above 0.5% — fails the lot.

02

Mass-Spec Identity

Identity is confirmed by ESI-MS on the same analytical run series. The observed mass is deconvoluted from the charge-state envelope and compared against the theoretical monoisotopic mass of the target sequence. We require agreement within ±0.5 Da — close enough to catch a single-residue deletion or an oxidized methionine.

03

Endotoxin — ≤0.05 EU/mg

Bacterial endotoxin is quantified by kinetic chromogenic LAL per USP <85>, with inhibition/enhancement controls run on each matrix. Our release limit of 0.05 EU/mg sits well below typical cell-culture thresholds, so a vial won't be the variable that confounds a sensitive in-vitro assay.

04

USP <71> Sterility

Finished vials — not just bulk material — are tested by membrane filtration and incubated 14 days in both fluid thioglycollate (anaerobes) and soybean-casein digest media (aerobes and fungi). Growth promotion and method-suitability controls accompany every run. No turbidity, no release.

05

ICP-MS Heavy Metals

Elemental impurities are screened by inductively coupled plasma mass spectrometry following USP <232>/<233>, with lead, arsenic, cadmium and mercury quantified to parts-per-billion sensitivity. Results are reported against the most conservative parenteral-class permitted daily exposure limits.

06

Net-Content Assay

Label claim is verified per lot by quantitative HPLC against a certified external reference standard, corrected for peptide content rather than gross lyophilizate weight — counterions and residual water don't count. A vial labeled 10 mg must assay between 95% and 105% of claim to ship.

Chain of custody

From reactor to your bench

Six checkpoints, one unbroken record. The lot number assigned at synthesis follows the material through every gate below.

  1. Synthesized in the USA

    Solid-phase synthesis, cleavage and preparative purification are completed at our audited, GMP-compliant US synthesis partner. Every lot receives a unique identifier at this point — the same lot number that ends up printed on your vial label.

  2. Internal QC gate

    Our in-house analytical bench runs first-pass HPLC and mass-spec on the purified bulk. Material that doesn't clear internal specifications never reaches fill-finish, let alone a third-party lab.

  3. Independent third-party analysis

    Samples from the finished, vialed lot are sent to an accredited, independent US analytical laboratory for the full six-layer panel. The lab has no stake in whether a lot passes — that's the point.

  4. Quarantined until pass

    The entire lot sits in quarantine, physically segregated from releasable inventory, until every result is back and within specification. A single out-of-spec value fails the whole lot. No partial releases, no exceptions.

  5. Lot-matched COA printed

    Passing results are compiled into a Certificate of Analysis tied to that specific lot number. It's printed and packed with every order from the lot — the certificate in your box describes the vial in your hand.

  6. Cold storage & same-day dispatch

    Released lots move to temperature-controlled storage at −20°C. Orders placed before 2 PM EST ship the same business day in insulated, discreet packaging built to protect lyophilized stability in transit.

Reading the document

How to read your COA

Every Peptide Labs Certificate of Analysis is organized into the same five blocks, top to bottom. Here's what each one tells you — and what to look for.

The header ties the document to a single production run: compound name and sequence, catalog number, lot number, fill mass, manufacture date and retest date. Check the lot number here against the one printed on your vial label first — if they match, everything below describes your exact vial.
The full chromatogram is reproduced, not just a summary number. The main peak is the target peptide; purity is its area percent at 214 nm. Look at the baseline around the main peak — a clean trace with no shoulder peaks or late-eluting impurities is what ≥99% actually looks like. Retention time, column, gradient and run parameters are listed so the analysis can be reproduced.
Two numbers side by side: the theoretical mass calculated from the peptide sequence, and the observed mass deconvoluted from the ESI-MS spectrum. They should agree within ±0.5 Da. This is the identity check — purity tells you how much of one thing is in the vial; mass-spec tells you that the one thing is the right thing.
The biological safety block: LAL endotoxin result in EU/mg against our ≤0.05 EU/mg limit, and the USP <71> sterility outcome (no growth at 14 days in both media). Both are run on finished vials from the lot, so the result reflects the sealed product — fill, stopper and all — not just the bulk powder.
The certificate closes with the reviewing analyst's signature, the date of review, and the independent laboratory's identity and accreditation. This block is what separates a real COA from a marketing document: a named, accredited third party stands behind every value above it.

Verify any lot

Your vial, your certificate

COA lookup

Every order ships with its paper COA — and every lot is on file.

Enter the lot number printed on your vial label to see the independent laboratory results for that exact production lot — purity, identity, endotoxin and net content — with the full PDF linked where published. Older lots not yet online can be requested from support@peptidelabs.supply.

Look up a certificate

Lot format: PL-#### · printed on every vial label

All Peptide Labs compounds are supplied strictly for in-vitro laboratory research by qualified professionals. They are not for human or veterinary use of any kind, and nothing on this page is a claim of therapeutic effect.

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