Frequently Asked Questions

Research peptide supply, quality assurance, ordering and shipping information

Peptides are short chains of amino acids, typically between 2 and 50 residues, joined by peptide bonds. They are widely used in pharmaceutical research, immunology, cell biology and drug discovery.

Our peptides are produced via solid-phase peptide synthesis (SPPS), which is the industry standard for research-grade peptides. Amino acids are added one at a time to a growing chain on a resin support. Once the full sequence is assembled, the peptide is cleaved from the resin, purified by reverse-phase HPLC, and freeze-dried into a stable powder.

This gives us precise control over sequence, purity and consistency. In-house testing confirms purity and identity, and CoAs are available to download on each product page.

Some of our peptides contain mannitol as an excipient. Mannitol is a sugar alcohol used as a bulking agent during freeze-drying. It helps keep the peptide stable during lyophilisation and produces a more visible, uniform cake in the vial.

Mannitol is inert and does not affect peptide purity or interfere with research assays. Each product listing states whether mannitol is present. If you need a mannitol-free version for a specific application, get in touch and we can check availability.

Minor cosmetic differences between vials are normal and do not indicate a quality issue. You may see slight variations in the appearance of the freeze-dried cake (from a compact disc to a looser powder) or different cap colours between batches.

Not all vials are sealed under vacuum. Whether a vial is vacuum-sealed depends on the manufacturer and the peptide itself. Some are nitrogen-flushed instead. The presence or absence of a vacuum seal does not affect quality or purity, as long as the vial has been stored correctly (sealed, refrigerated, away from light).

If you have any concerns about a vial (for example a broken seal or visible contamination), send us some photos and we will look into it.

Vial sizes and peptide quantities vary by product and are listed on each product page. Common sizes are 2mg, 5mg, 10mg and 15mg, with some products available in larger quantities.

All vials are standard laboratory-grade borosilicate glass with crimped aluminium seals and rubber stoppers. Product pages list the exact peptide content per vial. If you need a quantity not listed on the website, let us know.

Freeze-dried peptides are stable when stored correctly. As a rough guide:

• Lyophilised, refrigerated (2-8°C): Typically stable for 24 months or longer, depending on the sequence. Peptides prone to oxidation (e.g. those containing methionine or cysteine) may have a shorter shelf life.
• Lyophilised, frozen (-20°C): Extended stability, often over 36 months.
• Reconstituted: Stability varies by peptide and solvent. Most reconstituted peptides should be aliquoted and stored frozen. Avoid repeated freeze-thaw cycles.

We recommend storing all freeze-dried products in a fridge or freezer, in the original sealed vial, away from light and moisture. If you need stability data for a specific peptide, get in touch.

Proper handling and storage are important for keeping peptides in good condition. Here is what we recommend:

• Temperature: Store freeze-dried peptides at 2-8°C (fridge) for short-term use or -20°C (freezer) for long-term storage.
• Light: Keep away from direct light. UV can degrade certain residues, particularly tryptophan and tyrosine.
• Moisture: Keep vials sealed until ready for use. Freeze-dried peptides absorb moisture from the air, which speeds up degradation.
• Handling: Let refrigerated or frozen vials reach room temperature before opening, to prevent condensation forming inside the vial.
• After reconstitution: Aliquot into single-use volumes if possible and store frozen. Avoid repeated freeze-thaw cycles.

Handle peptides using standard laboratory practices for research chemicals. MSDS sheets are available on request for any product in our catalogue.