Start with the identity and lot
Match the compound name, presentation and lot identifier on the vial to the report. A certificate for the same compound from another batch does not identify the material in front of you.
Open the laboratory document rather than stopping at a headline percentage. Check the laboratory, report identifier, sample identifier and dates. If the sample name is abbreviated, ask how it maps to the supplied material.
Read the measurement with its method
Purity is a proportion expressed on a particular basis. Read the measurement method and reporting basis alongside the number. Do not silently substitute mass fraction for a different type of fraction.
A chromatographic peak area is a detector measurement. Interpreting a normalized area as the amount of material requires the method and its response assumptions. Ask what was measured if the report only says “purity.”
Source 1 ↓Source 2 ↓Look for separate answers
Identity, purity, quantity and microbiological testing are separate questions. Check which tests are actually present; a result for one does not by itself answer the others.
For a blend, check whether each named constituent is identified and whether the report gives component amounts or ratios. A single percentage is not a complete composition statement.
Keep the record and ask a specific question
Save the original report with the order record. If something does not match, send support the compound, lot identifier and the field in question. That makes it possible to investigate the exact material rather than discuss a generic product.
A research publication and a batch certificate serve different purposes. A paper describes an experiment; the certificate records testing of a submitted sample.