Laboratory Guides
Practical notes on handling research materials. They are provided for reference only; your laboratory's protocols always take precedence.
How to read a certificate of analysis
First, confirm that the batch number on the certificate matches the number on the vial label. A certificate issued for a different batch provides no information about your vial.
Purity by HPLC is read from the chromatogram: a tall, narrow main peak with small secondary peaks. The reported percentage is the area of the main peak relative to the total.
Mass spectrometry confirms identity: the observed mass should match the theoretical mass of the peptide within a narrow tolerance.
Storage of lyophilized materials
Lyophilized powder is stable but not indestructible. It should be kept refrigerated, dry and protected from light, in its sealed vial.
Moisture is the principal risk. Allow the vial to reach room temperature before opening it, so that condensation does not form inside.
Once in solution, stability decreases considerably. Record the preparation date and follow your laboratory's protocols for storage.
Traceability: what to record for each batch
Batch number, date of receipt, certificate of analysis and storage conditions. With these four records, any result can be traced back to its source.
When an experiment produces an unexpected result, the batch should be the first variable that can be ruled out. For this reason, batches should not be mixed within the same series.