A Certificate of Analysis (COA) is the primary quality documentation for a research peptide batch. Reading it correctly allows researchers to verify compound purity, confirm identity, assess testing methodology, and identify documentation gaps before procurement. This guide covers each section of a standard peptide COA.

Section 1: Batch and Product Identification

Every research-grade COA should include: compound name (full IUPAC name or common research name), amino acid sequence where applicable, lot or batch number (unique to this specific production run), CAS number if assigned, molecular formula, and theoretical molecular weight. The lot number is the critical link between the COA and the specific vial received.

Section 2: HPLC Purity Data

The HPLC section reports purity as a percentage — the ratio of the main peak area to the total detected peak area. Research-grade peptides should show ≥98% purity. More important than the number is the supporting chromatogram: a graphical plot showing each peak’s retention time, area, and height. Evaluate the chromatogram for:

• A dominant primary peak with minimal secondary peaks
• Baseline separation between peaks (not merged or overlapping)
• Consistent retention time within expected range for the compound

Section 3: Mass Spectrometry Data

The MS section should show both the theoretical molecular weight (calculated from the amino acid sequence) and the observed molecular weight from instrument measurement. These values should agree within ±0.5 Da (or the instrument’s stated mass accuracy). Significant discrepancy indicates either the wrong compound or a modified sequence.

Section 4: Appearance and Storage

The COA should confirm appearance (white to off-white lyophilized powder) and storage conditions (typically -20°C long-term, 2–8°C short-term). These entries confirm that the compound was evaluated in its supplied physical form.

Red Flags

Missing lot number, no lab identification, purity percentage without chromatogram, no MS data, test date more than 12 months old, or identical COA documents applied to multiple different products.

OligoPoly Labs provides batch-specific COA documentation accessible through our COA verification center at /coa/.

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