Solvent Preparation and Cartridge Filling — Equipment Guide
Preparing solvent and transferring it into a pen cartridge is a simple bench procedure, but technique matters: aseptic handling protects the contents, and slow transfer protects delicate material from degradation. This guide covers the equipment and the method.
What You Need
- Sterile 3ml glass cartridges
- A sterile syringe (2–5ml) with a drawing needle
- Bacteriostatic water or the solvent specified in your supplier’s documentation, from a laboratory supplier
- Alcohol wipes and a clean, flat work area
- A sharps container for used needles
Preparing the Solvent
Wash your hands, wipe every septum (the rubber cap you pierce) with a fresh alcohol wipe, and let it dry. Draw the required volume of solvent slowly — our reconstitution calculator works out volumes and concentrations for you. When adding solvent to any dry material, run it gently down the inside wall of the vial rather than jetting it directly; swirl, never shake. Foaming and agitation are the classic causes of degraded material.
Filling the Cartridge
Wipe the cartridge septum, then inject the prepared solution slowly into the cartridge, keeping the needle tip against the glass wall. Fill to no more than the 3ml line, withdraw the needle, and check for large air bubbles — a gentle tap brings them to the top, and the pen’s priming step clears the rest. The full loading procedure is covered in how to fill and use a pen cartridge and how to use your pen.
Afterwards
Label the cartridge with the date and concentration, refrigerate it at 2–8°C (see cold storage), and dispose of needles in your sharps container. Used septa should not be re-pierced with a dirty needle — one fresh needle per draw is the rule that keeps everything sterile.