How to read a Certificate of Analysis

Start with the document identity

Begin with the compound name, sample description, lot or batch identifier, laboratory, report identifier and dates. These fields connect the analytical results to a particular record. A similar product name or a matching nominal amount is a useful starting point, but it does not replace the lot details.

ICH Q7, a pharmaceutical manufacturing guidance, illustrates a structured COA format that includes batch information, tests, acceptance limits and results. Use those distinctions when reading a report rather than treating its heading or logo as the analytical conclusion.

Sources: ICH / U.S. Food and Drug Administration

Read each test as a separate question

Follow one row across the page: what was tested, which method was used, what result was obtained, and which specification was applied? Keep those fields together in your notes. A numerical result and the limit used to assess it have different roles; neither should disappear when a result is summarized.

Read qualitative labels in their stated context. A report marked “tested” records a testing status; it should not be silently rewritten as “passed.” If a method, unit or acceptance criterion is unclear, ask a question about that exact row and retain the original wording while it is clarified.

Sources: ICH / U.S. Food and Drug Administration · EliteGen Research

Keep the units attached

The amount printed in a sample name is a nominal label amount. An assay is a measured result under the reported procedure. A value in mg per vial describes a quantity associated with a vial, while mg/g describes a mass relationship. A percentage requires its stated basis: peak area, mass fraction or another defined quantity.

Do not convert between these expressions using the product name alone. Conversions can require additional information about the sample and calculation basis. When two fields appear inconsistent, preserve both values and their units instead of choosing the interpretation that looks most convenient.

Sources: International Union of Pure and Applied Chemistry · EliteGen Research

Keep the conclusion with its sample

The report date, sample identifier and lot remain part of the result when the PDF is downloaded or shared. A report for one amount or lot should not be silently applied to another. If several reports are available, compare their identifiers before interpreting differences between their numbers.

Formal reference-material reports also define their intended use and the status of their assigned values. That practice is a useful reminder to read a document’s scope, rather than assuming that every number on every certificate carries the same meaning.

Sources: National Institute of Standards and Technology · EliteGen Research

Make a short review record

Save the complete original PDF with the corresponding product documentation. A short index makes later review easier without replacing the source document. The National Cancer Institute emphasizes method documentation and standard operating procedures when measurements must be reproduced or transferred between laboratories.

• Record the report identifier, sample name, amount, lot and date.
• List the test, result, units and specification together.
• Note any question using the exact field or page it concerns.
• Keep conclusions limited to the tests and sample actually described.

Sources: National Cancer Institute · EliteGen Research