How to Read a Certificate of Analysis

What a COA is

A Certificate of Analysis (COA) is a document issued by a laboratory that reports the results of specific tests performed on a specific batch of material. A COA describes that batch only — it does not describe other lots of the same compound.

Identify the batch first

Before reading any result, confirm that the batch or lot number on the document matches the number printed on your vial or packaging. A COA that cannot be matched to your lot provides no information about the material you hold.

• Product / compound name
• Batch and/or lot number
• Date of analysis and issuing laboratory
• Methods used and the results reported

Common analytical methods

High-performance liquid chromatography (HPLC) separates the components of a sample. Results are typically shown as a chromatogram, where the area of the main peak relative to total peak area is reported as chromatographic purity under the stated method conditions.

Mass spectrometry (MS, or LC-MS when coupled to chromatography) measures the mass-to-charge ratio of ions. It is commonly used to confirm that the observed molecular mass is consistent with the expected identity of the compound.

Other tests — such as net peptide content, water content, endotoxin or sterility — are separate methods. A COA only supports the specific tests it actually reports.

What to look for

Look for the method name, the instrument conditions or a reference to the method, the actual chromatogram or spectrum where available, and a signature or identifier for the issuing laboratory. Results should be reported as measured values, not marketing language.

How Steel Peptides publishes documentation

Steel Peptides publishes analytical documentation in the Lab Documentation section when it is available, organized by compound, batch and lot number. Where no document has been published, the product page states so plainly.