Methodology

How we pick sources

We don't rank suppliers by price alone. A cheap vial of the wrong compound is worthless. Every source on PeptideSmart is scored against a transparent 9-point standard built around certificate-of-analysis (COA) coverage and third-party testing. Here's exactly how it works.

In-stock and verifiable first

A source only appears as a recommendation if the product is in stock and the supplier publishes — or provides on request — a certificate of analysis. No COA, no recommendation. Price is the last tiebreaker, never the first filter.

Core tests carry the most weight

Four tests are non-negotiable for any legitimate research supplier. They're inexpensive, fast, and directly tied to whether the compound is what the label claims and safe to handle. A supplier missing these drops sharply in our ranking regardless of price.

Identity (Mass Spec)Core

Confirms the peptide is what the label says. Mass spectrometry verifies molecular weight matches the target compound. Industry standard for any legit COA.

~$50-100/batch

HPLC PurityCore

Tells you the actual % of correct peptide vs impurities. Look for ≥98%. The single most important test.

~$100-200/batch

Net Peptide ContentCore

Actual mg of active peptide per vial vs. label claim. A 5mg vial might only contain 3.5mg of actual peptide. This catches mislabeled products.

~$150-250/batch

SterilityCore

Tests for bacteria, yeast, and mold contamination. Important for injectable research applications.

~$200-400/batch

3rd-Party LabCore

Testing performed by an ISO-accredited independent lab (Janoshik, Eurofins, etc.) — not in-house. Removes conflict of interest.

Lab choice

Bonus tests separate good from excellent

These tests are more expensive and not realistic on every single batch, so we treat them as signals of a supplier going above the baseline — not as disqualifiers. Suppliers that run them consistently earn our highest tier.

Endotoxins (LPS)Bonus

Detects bacterial cell-wall fragments that survive sterilization. Lower is better.

~$300-500/batch

Heavy MetalsBonus

Tests for lead, mercury, arsenic, cadmium contamination. Most suppliers test quarterly, NOT per batch — costs $400-600 alone. Quarterly testing is acceptable industry practice.

~$400-600/batch

Residual SolventsBonus

Detects leftover synthesis chemicals like TFA and acetonitrile. Important for highly pure preparations.

~$200-400/batch

Lot TraceabilityBonus

COA, vial label, and packaging all reference the same lot/batch number. Confirms you got the actual tested product.

Process discipline

What we don't do

We don't accept payment for higher rankings. We don't write fake reviews. We don't inflate every supplier to a perfect score — if that were true, the score would be meaningless. When we can't verify a supplier's testing from public information, we mark it unknown rather than guessing in their favor.

Affiliate disclosure

Some outbound links are affiliate links, meaning we may earn a commission if you purchase. This never changes a supplier's score or ranking — the methodology above is applied identically to partners and non-partners. See our full affiliate disclosure.

For research use only

Everything on PeptideSmart is informational and intended for licensed researchers and laboratory professionals. Nothing here is medical advice or a recommendation for human consumption.