How do researchers verify the purity and stability of a pharma grade peptide?

Hello everyone, I’m currently working on a research project that involves using several peptide compounds, and I wanted to ask about best practices for verifying the purity and stability of a pharma grade peptide before using it in laboratory experiments. When sourcing peptides for research, what quality indicators do you usually check first? For example, do you rely mainly on HPLC reports, mass spectrometry data, or certificates of analysis to confirm the purity of a pharma grade peptide? I’m also curious about storage and handling practices once the peptide arrives in the lab. Do most researchers keep lyophilized peptides at -20°C or -80°C, and are there specific steps you take to prevent degradation after reconstitution? Any advice on selecting reliable peptide suppliers and ensuring consistent research quality would be greatly appreciated. I’d love to hear what protocols other labs follow when working with pharma grade peptides. Thanks in advance for your insights! ??