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HPLC — Purity Analysis

High-Performance Liquid Chromatography separates the components of a sample by passing it through a column under high pressure. The detector measures absorbance at 220 nm (peptide bond detection), producing a chromatogram with peaks for each compound present.

HPLC is the gold standard for peptide purity determination. It directly measures the percentage of your target compound vs. impurities, truncated sequences, and degradation products. A clean, single dominant peak at ≥98% area confirms what you ordered is what you got.

ESI-MS — Mass Spectrometry

Electrospray Ionization Mass Spectrometry measures the mass-to-charge ratio (m/z) of ionized molecules. For peptides, this confirms the exact molecular weight of the compound to within ±0.5 Da, and can detect intact sequences vs. truncated fragments.

Purity alone is insufficient — a compound could be 99% pure but the wrong molecule. Mass spec confirms that the dominant peak on HPLC is actually the peptide you ordered. It catches synthesis errors, sequence truncations, and incorrect compounds at the identity level.

LAL Endotoxin Testing

The Limulus Amebocyte Lysate (LAL) assay uses a clotting extract from horseshoe crab blood to detect lipopolysaccharide (LPS) endotoxins from gram-negative bacterial contamination. Results are expressed in EU/mg (Endotoxin Units per milligram).

Bacterial endotoxins are invisible to HPLC and MS but can cause severe biological effects in in vitro and in vivo research — confounding results and destroying cell culture experiments. We test select batches for endotoxins and report results on the Certificate of Analysis.

Visual & Physical Inspection

Each vial is visually inspected for color, appearance, and particulate matter. Lyophilized (freeze-dried) peptides should be a white to off-white powder or cake with no discoloration, clumping from moisture, or foreign particles.

Visual inspection catches gross contamination, moisture exposure, and packaging failures before any analytical testing. A vial that fails visual inspection is quarantined and sent back — it never reaches our shelves regardless of accompanying documentation.