What to Look for on a COA Like a Real Researcher

HPLC is the primary tool used to determine how pure a peptide is. It separates a sample into its individual components so you can see how much of it is actually your target peptide.

Here’s the simple version:

1. The sample is dissolved.
2. It’s pumped at high pressure through a specialized column.
3. Different molecules interact with the column’s “stationary phase” at different rates.
4. Because they move at different speeds, they separate over time.

Think of it like a molecular race. Each compound takes a slightly different path and finishes at a different moment.

The result is a graph called a chromatogram. It shows several peaks. Each peak represents a different component in the sample. The largest peak is usually your target peptide.

Purity is based on the Area Under the Curve (AUC). You compare the area of the main peak to the total area of all detected peaks:

Purity % = (main peak area ÷ total peak area) × 100

So if your main peak makes up 99% of the total area, your peptide is 99% pure by HPLC.

HPLC helps ensure that the concentration of your compound in in-vitro models is accurate and free from synthesis byproducts.

And yes — the “remaining 1%” matters. Manufacturing impurities such as residual solvents, counterions, or truncated chains can interfere with cellular signaling. That can lead to noisy, inconsistent, or non-reproducible data.