8 mm Screw Cap

• Open top caps are designed to be used with any of our 8 mm septa
• Phenolic caps are suitable for autoclaving and low temperature applications
• Polypropylene caps are chemically inert and suitable for most chromatography applications
• Flanged caps are preferred for Shimadzu, Hitachi and Tosoh autosamplers
• Kim-Lok cap/septum assemblies feature a molded centering ring to eliminate septum movement during injection
• Pre-assembled caps and septa are convenient and minimize contamination from handling
• Closures are shipped in sealed polybags to prevent contamination during transport

PTFE/Natural Red Rubber Septa

PTFE/Natural Red Rubber are moderately priced seals for GC and HPLC with good chemical properties. They are ideal for multiple injections due to high resealability, but not as easy to penetrate as PTFE/Synthetic Red Rubber.

PTFE/Synthetic Red Rubber Septa

PTFE/Synthetic Red Rubber septa are an economical choice for general GC and HPLC applications. Used primarily for routine analysis in gas chromatography with FID, TCD and FPD detectors or HPLC with UV/Vis or RI detectors, PTFE/Synthetic Red Rubber septa offer good resealability and excellent chemical inertness before puncture. The low durometer of red rubber allows for easy needle penetration even with thin bore GC needles. PTFE/Red Rubber septa are not recommended for multiple injections with long run times or retention of samples for further analysis after initial puncture.

PTFE/Silicone Septa

PTFE/Silicone is the most versatile septum material offered in various formulations to address specific applications requirements. Extractables from PTFE/Silicone septa are generally at lower levels compared to other resealable materials. PTFE/Silicone septa are formulated for different hardness (durometer) meeting requirements of various needle types. Formulations offering highly consistent performance, lowest background/blank value, and good chemical compatibility, effective sealing/resealing and low penetration force make PTFE/Silicone septa suitable for all types of chromatographic applications. A thin film of PTFE is laminated to the side of the septum that faces the sample to limit exposure of the elastomer to the solvent. PTFE/Silicone septa are ideal for use in most HPLC and GC applications where resealability and purity are critical.

Pre-slit PTFE/Silicone Septa

Pre-slit septa are offered in many of the same formulations as for non-slit PTFE/silicone septa and shares most of the physical and chemical characteristics. The septum is provided with a thin 0.005” PTFE layer laminated to highly pure silicone, and slit through the center for easier needle penetration and to release the vacuum that forms when a large volume of sample is withdrawn from a vial. This septum provides chromatographic characteristics similar to that of a septum without a slit, except that the ability to withstand exposure to aggressive solvents is slightly lessened. Pre-slit septa are highly recommended for Shimadzu, Hitachi, and other autosamplers with thin gauge needles.

PTFE/Silicone/PTFE Septa

A layer of inert PTFE film is laminated to each side of high-purity, medium durometer silicone to form a septum that is resistant to coring, but still maintains good resealing characteristics. PTFE/Silicone/PTFE septa are recommended for the most critical applications such as ultratrace analysis, where there is a longer time between injections. PTFE/Silicone/PTFE septa provide superior performance with any autosampler employing a large diameter, blunt-tip needle. PTFE/Silicone/PTFE septa can have benefits when working with solvents that tend to attack silicone by protecting both sides of the elastomer.

Polypropylene Septa

Chemically resistant polypropylene septa are available as thick disks inserted into closures.  The surface for needle penetration is 0.01" thick allowing for use with most HPLC autosamplers.  Polypropylene septa are not resealable and are intended for single injection use with aqueous based sample mixtures.  Polypropylene septa offer better solvent compatibility compared to polyethylene, but piercing force is slightly higher.

• Thermo Scientific Sample Handling Catalogue

  Contains details on Thermo Scientific's sample handling products

• SAMPLE HANDLING TECHNICAL BROCHURE

  Contains full technical information on Thermo Scientific's sample handling products