How to choose a suitable septa

**Author: Original from Internet

Many customers place great importance on sample vials, yet overlook the choice of caps and seals; in fact, this is also of considerable importance. Choosing the right seal can lead to better experimental results.

We have now put together a detailed guide. Let's take a look at how to choose the right seal for different requirements.

Combines the corrosion resistance of PTFE with the sealing properties of silicone, and has a wide temperature range: -40°C to 200°C.

For highly permeable normal-phase solvents, such as n-hexane and dichloromethane, swelling may occur if the liquid level is too high. (Note: PTFE = polytetrafluoroethylene, Teflon)

For use with blunt or fine-tipped injection needles

Eliminates blockages at the base of the needle following injection

Prevents a vacuum from forming inside the sample vial

Operating temperature range: –40° to 200°

Recommended for repeated injections

Suitable for high-pressure and high-temperature sterilisation

For internal standards, trace analysis or experiments with long intervals between injections

Operating temperature range: –40° to 200°

PTFE/silicone rubber/PTFE septa offer the same chemical compatibility as PTFE septa until punctured. For highly sensitive samples, we recommend using PTFE/silicone rubber/PTFE septa, as the PTFE layer acts as a chemically resistant barrier.

The gasket is bonded to the cap using an adhesive-free process. The PTFE layer of the composite gasket comes into contact with the reagents; it possesses excellent chemical inertness and is resistant to acids, alkalis, high temperatures and sticking. It remains chemically inert even when exposed to concentrated acids, concentrated alkalis or strong oxidising agents at high temperatures, whilst the elasticity of the silicone rubber ensures a secure seal; It also ensures that the gasket remains securely attached to the cap during transport and, during piercing, prevents the gasket from being pushed into the sample vial, even when using a very thick or blunt sampling needle.

Made from nitrile silicone, offering excellent puncture resistance

Suitable for sealing sample vials at temperatures up to 210°C. Recommended for storage and repeated injection use

The star-shaped design features a pressure-relief function, capable of withstanding pressures up to 60 psi, ensuring safe operation under the high pressures generated during temperature-controlled processes. Standard bottle caps lacking these safety features may rupture

Temperature range: –50 °C to 150 °C

Suitable for organic solvents and acetic acid; excellent sealing performance effectively prevents gas leakage

Economical, suitable for storing non-corrosive samples; not recommended for long-term storage of liquids; may only be stored at room temperature