Reconstitution fundamentals: diluent choice and handling technique

Starter thread on reconstitution. This post covers general lab handling only. Concentrations and amounts depend on the compound and the protocol you’re following, so check the primary source for those.

Choosing a diluent

• Sterile water has no preservative. It’s appropriate for single-use preparations.
• Bacteriostatic water (water with 0.9% benzyl alcohol) inhibits microbial growth. That’s why it’s commonly used when a vial will be accessed more than once.
• Some hydrophobic or aggregation-prone sequences don’t dissolve well in water alone. Published methods sometimes use dilute acetic acid or other solvents. Check the sequence and the literature before improvising.

Technique

• Let the vial reach room temperature first.
• Run the diluent slowly down the inside wall of the vial instead of jetting it straight onto the powder.
• Swirl or roll gently. Don’t shake. Vigorous agitation can cause foaming and aggregation.
• Use aseptic technique: swab the stopper, use sterile supplies, and don’t reuse them.
• Label the vial with the date and concentration once it’s made up.

If it won’t dissolve

Persistent cloudiness or particles can mean an incompatible diluent, aggregation, or a product problem. Don’t assume it’s fine just because some of it went into solution.

Questions about specific compounds or problem cases are welcome below.