Lab Testing & Purity

Every batch of research-grade peptide Pepreta supplies is analytically characterised before it is listed for sale. A Certificate of Analysis (COA) summarising the test results is available to download on each product page for tested batches, and the full set is linked below.

What we test and why

Reproducible peptide research depends on knowing exactly what is in the vial. A compound that is impure, misidentified or contaminated with endotoxin will produce unreliable results and waste research time. Our standard testing protocol covers three independent analytical methods:

Purity — RP-HPLC (220 nm): Reversed-phase High-Performance Liquid Chromatography separates the sample components and quantifies the main-peak area as a percentage. Our specification is ≥99.0% purity by HPLC area. A peptide at this purity level is overwhelmingly the intended compound with minimal related impurities — the threshold used in pharmacopoeial research standards.
Identity — Mass Spectrometry (ESI-MS): Electrospray ionisation mass spectrometry confirms the molecular mass of the peptide matches its theoretical value. This independently verifies that what the HPLC is measuring is actually the correct compound — not an isobaric impurity or a truncated sequence with similar retention time.
Endotoxin — LAL Gel-Clot: The Limulus Amebocyte Lysate assay screens for bacterial endotoxin (lipopolysaccharide). Our specification is <0.5 EU/mg. Endotoxin contamination is a common confound in cell-based and in-vivo assays — it activates immune pathways that can mask or mimic the effects of the peptide being studied. Passing the LAL screen means the material is suitable for sensitive biological assays.

What a Certificate of Analysis contains

Each COA references a specific lot number, test date, and the results of the three assays above. This lot-specific documentation means you can verify the actual batch you received — not a generic or recycled certificate. The COA also states the compound name, form (lyophilised powder), appearance, and storage conditions.

Why three tests and not one

Each analytical method answers a different question. HPLC measures how much of the sample is the target compound. Mass spectrometry confirms what that compound actually is. The LAL assay checks for a class of contaminant that HPLC cannot detect. Together they provide orthogonal verification — a compound that passes all three is characterised from multiple independent angles, which is the standard expected in rigorous peptide research.

Compounds with Certificates of Analysis

COAs are provided for informational purposes and apply to the referenced lot only. Results may vary between lots. Download the current COA from each product page, or from the list below. For a compound not yet listed here, contact us and we will provide the current batch analysis where available.

Interpreting your COA

When you receive a COA, check three things: that the lot number matches the vial you received (printed on the vial label), that the HPLC purity is ≥99.0%, and that the endotoxin result passes the <0.5 EU/mg specification. The mass spectrometry result will show the observed m/z (mass-to-charge) values alongside the theoretical values — these should match within instrument tolerance (typically ±0.5 Da for small peptides, ±2 Da for larger sequences).

Note on provenance. Pepreta provides these batch-analysis certificates for informational purposes. They do not constitute a medical, safety or fitness-for-purpose certification, and are not a substitute for a researcher's own verification. All products are supplied for laboratory research use only — not for human or animal consumption.