Choosing the right vial is crucial when collecting samples. Equally as important is making sure you have the right septa caps. Septa caps protect the collected sample from spills, contamination, and evaporation, and should form an airtight seal and be inert. Needles can easily pierce the septum because the elasticity of the material allows for reclosure.
Chemical resistance with the sample and solvent ability are generally the main factors when choosing a cap. The individual physical and chemical properties of the various septa materials are another important component in considering the right kind of closure. The best choice usually will depend on the needle type as well as the temperature, sensitivity of the sample, and if single or multiple injections will be needed.
Ensuring you have the right septa caps will ensure the sample’s integrity will not be impacted or contaminated. In this blog we will outline the difference between pre-slit and non-slit caps.
Pre-Slit Septa Caps
Pre-slit septa caps work best for automatic sampling because the pre-slit processing makes it easy to puncture the sample feeder’s injection for sampling. Despite the slit, these caps can also maintain the sample seal without creating a vacuum in the air pressure inside the vial.
Pre-slit septa caps also reduce the risk of needle bending, are easier to pierce with thin gauge needles, release vacuum from high-volume injections, and improve injection reproducibility.
Pre-slit caps should be used when a very low sample volume is being injected.
Non-Slit Septa Caps
Non-slit septa caps can help reduce carryovers because the re-sealing properties of the septum act as a barrier from the outside of the needle. Non-slit septum caps resealing properties only allow for a limited number of needle punctures. These caps are recommended when the vials are being stored for long periods of time.
Non-slit caps also can offer protection from evaporation until the septum is pierced.
Whether using pre-slit or non-slit septa caps, be careful with how you store your caps before use. Do not store septum where chemical vapors are present for long periods of time.
Integrated Liner Technologies offers a range of pre-slit or non-slit septa caps.
Our silicone/PTFE caps provide excellent resistance to solvents and are easy to penetrate. Our silicone red rubber caps are a popular and affordable option for standard gas chromatography uses.
All of our products are made in the USA and are tested on our on-site laboratory to ensure quality and customer satisfaction. Learn more about our products.
September 29, 2022
Integrated Liner Technologies Inc.