Start with the measurement, not the largest percentage
A COA is useful when it describes the sample being evaluated and states which measurements were performed. A purity number should not replace a check of identity, specification and batch. Keep the complete original record.
Chromatographic purity
HPLC purity commonly reports the main peak relative to peaks detected under the stated method. The method and detector influence what is measured. This is different from weighing the sample or establishing the mass of target peptide in a vial.
Peptide content and vial amount
Peptide content concerns the peptide fraction of supplied material; water, counterions and other constituents affect its relationship to gross powder mass. A labeled vial amount is another claim requiring an appropriate quantitative measurement. Multiplying a purity percentage by a label amount does not prove the amount supplied.
Identity and additional tests
Mass-spectrometric identity information and HPLC purity answer different questions. Neither should be presented as a sterility or endotoxin result unless that separate test is included. The laboratory's recorded test scope matters more than an assumed complete panel.
A before-payment checklist
- Match the full material name, molecular form and specification.
- Match the sample or lot reference to the proposed batch.
- Read the method and units for each measurement.
- Ask which quantitative tests are available if your specification requires them.
- Record what has not been tested instead of inferring a pass.
Sulan product pages label historical documents as historical records. Ask which documents can be supplied for the specification and batch offered in your quotation. Not every catalog entry has a complete analytical panel.