Documentation you can audit before you order.

Most research peptide suppliers ask buyers to trust a purity number printed on a product page. The number is rarely batch-linked, the method is rarely stated, and the certificate, when one exists, often describes no specific lot. The purchasing laboratory absorbs the risk: a contaminated or under-purity batch invalidates experiments that cost far more than the material itself.

The alternative is documentation that survives scrutiny. A batch-linked certificate of analysis carries a lot identifier that matches the vial label, names the analytical method behind every reported value, and is dated and attributable to a testing laboratory. Identity is confirmed by mass spectrometry against the theoretical mass of the stated sequence; purity is measured by reversed-phase HPLC with UV detection at 214 nm, not asserted. Endotoxin, heavy metals, residual solvents, and moisture content are measured separately, because none of them appear in a chromatogram.

Acceptance is binary. A batch below 98.0% purity, with a mass deviation beyond 0.5 Da, with any unidentified impurity above 1.0%, or with any contaminant above its specification limit is rejected — not re-blended, not discounted, not released at a lower grade. One in four batches is re-tested by an accredited external laboratory with no commercial relationship to the manufacturer, and release requires matching results.

This reference site exists so buyers can inspect those standards before spending anything. The testing methodology, the rejection thresholds, and the sourcing criteria are published in full. The catalog they describe belongs to Frontier Aminos, the supplier this reference maps to.