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How research peptides are made: synthesis, purification and drying

By BioGenisys Research Team · 5 min read · Updated 2026-10-27

Nearly every research peptide is made the same way: built one amino acid at a time on tiny plastic beads, cut free, cleaned up, and freeze-dried into a powder. Each step affects what ends up in the vial, and what a lab report needs to check.

The short version

• Peptides are built link by link, one amino acid at a time, like beads on a string.
• Small slip-ups along the way create slightly flawed copies, which the clean-up step removes.
• The finished peptide is freeze-dried into the powder you receive.

1. Building the chain

Amino acids are the building blocks of every peptide. The method used today, called solid-phase peptide synthesis, was invented by Bruce Merrifield in the 1960s and earned him the 1984 Nobel Prize in Chemistry. The first amino acid is attached to tiny plastic beads, and the chain is built from there, one amino acid per round, like adding beads to a necklace.

Each new amino acid arrives with a temporary chemical cap that stops it from joining in the wrong place. Every round has two steps: take the cap off the end of the chain, then attach the next capped amino acid. Everything is washed between steps, which is easy because the growing chain stays stuck to the beads.

2. Cutting it free

When the chain is finished, a strong acid (usually trifluoroacetic acid, or TFA) cuts the peptide off the beads and removes the remaining caps at the same time. What comes off is the raw, or crude, peptide: the right chain mixed with by-products.

3. Where impurities come from

• Missing links: a round that didn't fully work leaves some chains one amino acid short.
• Short chains: chains that stopped growing early.
• Leftover caps: a protective cap that didn't come off.
• Small chemical changes: for example, a reaction with oxygen in the air.

Most of these differ from the right peptide by only one building block or a few atoms, which is why they show up as small peaks right next to the main one on a purity chart.

4. Cleaning it up

The raw peptide is purified on a large version of the same HPLC equipment used for testing. The portion containing the right peptide is collected. The purity figure on a report shows how well this step separated the right peptide from its near-copies.

5. Freeze-drying

The purified liquid is frozen and then dried under a vacuum, which turns the ice straight into vapor. This is called lyophilization, and it leaves a light powder or small cake. The peptide comes out with a little salt attached from the process, usually TFA unless it was swapped. See Peptide salt forms.

6. Testing

Each batch is then checked for identity by mass spectrometry and for purity by HPLC, and often for net content. HPLC and mass spectrometry, explained shows how those tests work.

For research use only. Not for human or veterinary use.