Peptide Handling Guide

A laboratory handling reference for researchers receiving lyophilized peptides from Rewerk. This guide covers shipment storage, reconstitution with bacteriostatic water, solution stability, and freeze-thaw best practices.

On arrival

Lyophilized peptides are stable at room temperature for short periods. We ship under insulation when stability requires it. On receipt:

  • Inspect each vial — confirm intact seal, no visible moisture, label legible and matching the COA lot number.
  • Move the vial to your storage destination as soon as practical. Lyophilized stability windows assume cold storage.

Long-term storage (lyophilized)

For most peptides:

  • Short term (under 30 days): Refrigerator, 2–8°C, sealed.
  • Long term (over 30 days): Freezer, −20°C or below.

Avoid temperature cycling — repeated thaw-and-refreeze cycles introduce moisture and degrade peptide integrity over time.

Reconstitution

Lyophilized peptides are typically reconstituted with bacteriostatic water (BAC water) — sterile water containing 0.9% benzyl alcohol as a preservative. Some peptides require alternative solvents; check compound-specific guidance.

General procedure

  1. Bring the vial to room temperature before opening. Cold vials can pull moisture from ambient air.
  2. Wipe the rubber septum with an alcohol pad.
  3. Draw the required volume of BAC water into a sterile syringe.
  4. Tilt the vial slightly and inject the BAC water against the side of the vial wall — never directly onto the powder.
  5. Allow the powder to dissolve passively. Do not shake aggressively — gentle swirling is sufficient. Vigorous shaking can denature certain peptides.
  6. Once dissolved, the solution should be clear with no visible particulates. Discard any solution showing cloudiness or precipitate.

Concentration math

To achieve a target mg/mL concentration: BAC water volume (mL) = peptide mass (mg) ÷ desired concentration (mg/mL).

Example: a 5 mg vial reconstituted with 2 mL of BAC water yields 2.5 mg/mL.

Solution stability

Reconstituted peptide solutions are less stable than the lyophilized powder. As a general guideline:

  • Refrigerated (2–8°C): Most reconstituted peptides remain stable for 2–4 weeks. Some shorter.
  • Frozen (−20°C): Suitable for longer storage of reconstituted solutions when bacteriostatic preservative permits. Avoid repeated freeze-thaw.

Refer to compound-specific stability data on the product page or COA. When in doubt, prepare smaller working aliquots and store the bulk solution undisturbed.

Freeze-thaw best practices

  • Aliquot reconstituted solution into multiple small vials immediately after reconstitution. Each aliquot is a single-use stock.
  • Label each aliquot with compound, concentration, lot number, reconstitution date, and aliquot number.
  • Use one aliquot per experiment. Do not refreeze a thawed aliquot.

Working solutions

Working solutions for in vitro experiments are typically prepared by diluting the stock solution into the experimental buffer immediately before use. Working dilutions should be used the same day and not stored.

Disposal

Dispose of expired solutions and unused peptide in accordance with your laboratory's biohazard and chemical waste protocols.

Research use only

All Rewerk products are sold for in vitro laboratory research by qualified researchers. The handling procedures above are intended for laboratory use and are not instructions for human administration of any kind.