Every batch TITRACE ships includes a Certificate of Analysis. Most researchers glance at the purity percentage and move on but a COA carries more information than that one number, and knowing how to read it helps you catch a problem before it affects your data.
What's Actually on a COA
A proper COA identifies the specific batch (lot number), the compound and its CAS number, and two independent measurements: purity by HPLC and identity confirmation by mass spectrometry. Appearance and solubility notes are usually included too. If a COA is missing the lot number or shows no MS data, treat that as a gap, not a formality.
Purity by HPLC
High-performance liquid chromatography separates a sample into its components and reports each as a peak. The chromatogram summary lists retention time and peak area percentage for the main compound, plus any impurity peaks above the reporting threshold. The purity percentage quoted on a COA is the area of the main peak relative to total peak area, not an absolute measure of mass. A report showing 99.1% purity with one minor impurity peak at 0.6% is a cleaner result than 98.5% with several small peaks scattered across the trace, even though the headline number looks similar.
Identity Confirmation by Mass Spec
HPLC tells you how pure a sample is, not what it is. Mass spectrometry confirms identity by matching the observed mass to the expected molecular weight of the compound. A COA should state the expected mass and the observed mass, ideally with the deviation in a few parts per million. If a supplier only provides an HPLC trace with no MS confirmation, there's no independent check that the compound is what the label says it is.
Reading the Numbers in Context
Purity thresholds get treated as a pass/fail line, but the more useful question is what's making up the remainder. A small residual solvent or counter-ion peak behaves differently in solution than a related synthesis byproduct. When a COA breaks out individual impurity peaks instead of reporting a single lumped number, that's usually a sign of a more rigorous QC process, not a worse result.
What to Check Before You Trust a COA
- Lot number on the COA matches the lot number on the vial label
- CAS number and molecular formula match the compound ordered
- Both HPLC and MS data are present, not just one
- Test date and any expiration or retest date are listed
- The issuing lab or internal QC reference is identifiable
TITRACE publishes COA and HPLC reports for every batch listed on the product page, searchable by lot number. This article is provided for laboratory research and informational purposes only. TITRACE products are Research Use Only (RUO) and not intended for human or veterinary use.