What a Certificate of Analysis Actually Shows

A Certificate of Analysis is the lab document that says 'this batch matches what's on the label.' At minimum it identifies the compound, confirms the molecular weight, reports purity from a quantitative method (typically HPLC), and notes anything that should not be in the vial — heavy metals, residual solvents, microbial load, endotoxins.

It's a batch-specific document. The same COA cannot legitimately apply to multiple manufacturing batches. If a supplier shows you a COA from 2023 against a batch made in 2026, that's not a COA — that's a marketing artefact.

Compound identity (chemical name, sequence where peptide). Lab name and accreditation status (NATA in Australia, ISO 17025 internationally). Method of test (HPLC method specifics, mass spec parameters). Date of test. Batch number. Quantitative results with method-specific limits of detection. Raw chromatograms or spectra, not just summary numbers.

Bonus signals of quality: residual solvent testing, heavy metal testing, microbial load and endotoxin assays — particularly important for any compound intended for any sterile-context research use.

HPLC separates compounds by how they interact with a stationary phase. The output is a trace with peaks. Each peak is a compound or impurity; peak area is proportional to amount.

A clean main peak with no significant secondary peaks is a quality signal. Watch for: very narrow integration windows that hide impurities, a single peak with no axis labels, or a 'purity' figure quoted without showing the trace.

Mass spectrometry reports the molecular weight of what's in the vial. The reported mass should match the theoretical mass for the labelled compound within instrument tolerance — typically a few daltons.

If the mass spec shows a different molecular weight than the labelled compound, something is wrong: contamination, mis-identification, or degradation. This is the most common way fraudulent COAs are spotted on close inspection.