Insulin Syringes 31G × 1 mL

Why insulin syringes are used in peptide reconstitution

Insulin-style syringes combine three properties that make them well suited to peptide laboratory work: a fine, permanently attached needle, a narrow barrel with fine graduations, and very little dead space between the plunger tip and the needle hub. Together these let a researcher measure fractions of a milliliter reproducibly and transfer solution with minimal loss, which matters when the peptide in a vial is measured in milligrams.

Understanding the specifications

• Gauge (31G): higher gauge means a thinner needle. A 31G needle has an outer diameter of roughly 0.26 mm, small enough to pass through a rubber stopper many times without producing a leaking channel.
• Length (5/16 in): long enough to reach the contents of a standard 3 mL or 10 mL vial when the vial is inverted, short enough to stay rigid.
• Volume (1 mL) and graduations (0.01 mL): the whole barrel is used for reconstitution volumes of up to 1 mL per draw, and 1-unit markings make it straightforward to record exactly how much diluent was added.

Use in a reconstitution workflow

Choosing between 31G × 1 mL and 29G × 0.5 mL

The 1 mL barrel is the more versatile choice for reconstitution because it draws larger diluent volumes in a single pass. The 0.5 mL 29G version, offered separately, has a slightly heavier needle and a scale spread over a shorter volume, which some researchers prefer for small transfers. Many benches keep both on hand.

Keep syringes sealed in their individual wrappers, stored dry at room temperature, and discard any unit whose wrapper is torn or whose needle cap is loose. Peel the wrapper immediately before use and avoid touching the needle. Each syringe is single-use: use a fresh syringe for every vial entry to avoid cross-contaminating diluent, stock and working solutions. After use, do not recap the needle by hand; place the entire syringe directly into an approved sharps container and dispose of the container according to local regulations. Wipe every stopper with an alcohol prep pad before insertion.