How to Read a Certificate of Analysis (COA)

A Certificate of Analysis (COA) is a document issued by a testing laboratory that reports the results of quality-control tests performed on a specific batch of product. For research peptides, a COA confirms the compound's identity, purity, and safety profile before it reaches your bench.

Every reputable peptide supplier provides COAs for their products. The document ties analytical results to a specific manufacturing batch, creating a traceable chain of quality assurance from synthesis through delivery. Without a COA, there is no independent verification that the material in the vial matches what the label claims.

A well-structured COA contains four core sections that together paint a complete picture of product quality.

High-Performance Liquid Chromatography (HPLC) is the gold-standard method for measuring peptide purity. The technique separates a peptide sample into its components by pushing it through a column packed with fine particles. Each component exits the column at a different time, producing a chromatogram — a graph of signal intensity versus retention time.

The main peak on the chromatogram represents the target peptide. Purity is calculated as the area of the main peak divided by the total area of all peaks, expressed as a percentage. A result of 98% or higher means that at least 98% of the material in the sample is the intended peptide, with 2% or less consisting of synthesis-related impurities such as truncated sequences, deletion peptides, or residual protecting groups.

For research peptides, 95% purity is generally acceptable for in-vitro studies, while 98%+ is preferred for sensitive assays. The COA should state the column type (typically C18 reverse-phase), mobile phase composition, and detection wavelength (usually 220 nm for peptide bonds) so the test is reproducible.

While HPLC tells you how pure a sample is, mass spectrometry (MS) confirms what the sample actually is. The technique measures the mass-to-charge ratio of the peptide molecule, producing a molecular weight reading that can be compared against the expected theoretical mass.

For a peptide like BPC-157 with a theoretical molecular weight of 1,419.53 g/mol, the MS result should fall within a narrow tolerance — typically plus or minus 1 Da (Dalton) of the expected value. Common techniques include electrospray ionization (ESI-MS) and matrix-assisted laser desorption ionization (MALDI-TOF). The COA should report both the observed mass and the expected mass so you can verify the match.

If the observed mass deviates significantly from the expected value, it may indicate the wrong peptide sequence was synthesized, or that a chemical modification occurred during manufacturing. MS is a non-negotiable test for peptide identity — a COA that includes HPLC purity without MS confirmation is incomplete.

Endotoxins are fragments of bacterial cell walls (lipopolysaccharides) that can contaminate peptide products during manufacturing. Even at trace levels, endotoxins trigger potent immune responses, making this test especially important for injectable research materials.

The standard method is the Limulus Amebocyte Lysate (LAL) assay, which uses a reagent derived from horseshoe crab blood cells that clots in the presence of endotoxins. Results are reported in Endotoxin Units per milliliter (EU/mL). The USP limit for injectable products is less than 5 EU/kg of body weight. For research peptides, a common acceptance criterion is less than 0.25 EU/mL or less than 5 EU/mg of peptide.

A properly run LAL test includes positive and negative controls. The COA should report the method (gel-clot, turbidimetric, or chromogenic LAL), the sensitivity of the assay, and the observed result against the specification.

Sterility testing determines whether a product contains viable microorganisms. The reference method for pharmaceutical sterility is USP Chapter 71 (<71>), which involves transferring the product into two growth media — fluid thioglycollate medium (for anaerobic bacteria) and soybean-casein digest medium (for aerobic bacteria and fungi) — then incubating for 14 days.

If no microbial growth is observed after the incubation period, the sample passes. The COA should state the method reference (USP <71>), the media used, incubation conditions, and the pass/fail result.

Not all peptide COAs include sterility testing. Lyophilized research peptides are often tested for bioburden (microbial count) rather than full sterility, since they are reconstituted before use. However, products marketed as sterile — such as pre-filled vials — should always include USP <71> sterility data.

Not all COAs are created equal. Here are warning signs that a document may be unreliable or fabricated.

PharmaOrder makes Certificates of Analysis available for all research peptide products. To view the COA for a product you have purchased, log in to your account, navigate to your order history, and select the relevant order. COA documents are accessible from the order detail view when available for your product batch.

If you need a COA for a product before purchasing, visit the product page in our catalog — COA availability is noted in the quality information section. You can also contact our support team to request a specific batch COA.

All COAs provided through PharmaOrder are generated by independent third-party testing laboratories. We do not issue COAs internally — the analytical work is performed by qualified labs to ensure objectivity and accuracy.