Pen Cartridges (3ml)

3 ml glass — sterile, individually pouched, made for the pen

The glass cartridge that holds the solution in a refillable pen. Three millilitres, with a rubber septum crimped at the needle end and a sliding rubber plunger at the other, which the pen mechanism drives forward. Supplied sterile in an individual pouch. These come from the pen manufacturer and are made for the Pioneer pen kit rather than adapted from something else.

Specification at a glance#

• 3 ml capacity
• Borosilicate-type glass barrel
• Crimped rubber septum, sliding plunger
• Sterile, individually pouched
• Made by the pen manufacturer for this pen

Identity and specification#

What the cartridge does#

In a refillable pen the cartridge is the container and the measuring chamber at once. The pen screws shut around it, a lead screw advances against the rubber plunger, and the distance that screw travels is what the dial on the end is actually setting. Everything the pen claims about repeatability depends on the cartridge being the right internal diameter — which is why a cartridge made for the pen and a cartridge that happens to fit are not the same thing.

Why glass#

Glass is used for the same reason vials are glass: it is close to inert, it does not leach into the contents, and peptide adsorbs to it less readily than to most plastics. It is also transparent, so the contents can be inspected without opening anything — cloudiness, particulates or a stray fibre are visible through the barrel, and in a system where the solution is otherwise out of sight that matters.

The cost of glass is that it breaks. A cartridge that has been dropped goes in the bin even if it looks intact, because a hairline crack in the barrel is not reliably visible and will fail under the pressure the pen applies.

How many you need#

One, to use the pen at all — and the kit ships with one already. The case has a slot for a second, and the usual reason to keep spares is that one cartridge holds one solution at a time. Two cartridges means two preparations ready without emptying and cleaning between them, which is the practical argument for the pack of five.

The other reason is breakage. Glass in a case that travels is glass that will eventually meet a hard floor, and a spare in the lid turns that from a lost week into an inconvenience.

Filling and handling#

• Keep the pouch sealed until the moment of use — the pouch is the sterile barrier
• A pouch that has been opened, torn or has got damp is no longer one
• Inspect the glass against the light before loading: cloudiness, chips or particulates mean discard
• Swab the septum with a 70% isopropyl pad and let it dry before each entry
• Store loaded cartridges as you would any reconstituted material — cold, dark and upright
• Do not autoclave or attempt to re-sterilise a used cartridge

Our reconstitution calculator will work out the concentration and the volume of solvent to add, which is the number you need before the cartridge is filled rather than after.

What it fits#

The Pioneer pen kit, which is what these are made for. Three-millilitre cartridges are a common format and the dimensions are broadly standardised, but pens vary in how they clamp and drive the plunger. If you are fitting one to a pen bought elsewhere, check it against that pen’s own specification first.

Sizes and pricing#

Working with lyophilised peptides? See our pens, syringes and needles guide, reconstitution guide, storage guide and how to read a COA.