How to tell if your peptides have degraded

Since storage and handling errors happen, here's how to spot degradation.

Visual signs (lyophilized powder):

• Color change — should be white/off-white. Yellow or brown is bad.
• Collapsed cake — the freeze-dried cake should hold its shape. If it's melted or pooled at the bottom, it likely got warm.
• Moisture — any visible liquid or wet-looking powder means the seal was compromised.

Visual signs (reconstituted):

• Cloudiness or particles — should be clear. Cloudy = aggregation or contamination.
• Color change — clear to yellow means oxidation.
• Gel-like consistency — the peptide has aggregated. Don't use it.

Functional signs:

• Reduced or no effect compared to a known good batch
• Different injection site reaction than usual (could indicate contaminants from degradation)

What causes degradation:

• Heat exposure (even brief periods above 40°C)
• Light exposure (especially UV)
• Repeated freeze-thaw cycles
• Bacterial contamination (using sterile water without preservative for multi-dose)
• Age — even properly stored peptides degrade over time

When in doubt, toss it. The cost of a new vial is always less than the cost of injecting degraded product.