New ideas in high-integrity septa & cap liner technology

Home » Applications » Gas Chromatography

Gas Chromatography

Gas chromatography is a method for separating substances in a mixture and measuring their relative quantities. In preparation for analysis, the sample is dissolved in a solvent, vaporized, and carried by an inert gas through a column packed with a sorbent to any of several types of detector. Each substance is separated from the others by passage through the column, which produces a separate peak in the detector output. The higher a substance’s affinity for the sorbent, the more slowly it comes off of the column. The sorbent may be an inert porous solid or a nonvolatile liquid (or polymer) coated on a solid support.

GC Septa Characteristics

A wide array of gas chromatography septa designs are readily available. Depending on the analysis, standard organic-based septa, such as Butyl or Natural Rubber, may be used; or Silicone septa may be required if the vial needs to be re-sealed or temperatures above 100°C are realized. GC septa consist of a rubber layer and either one or two fluoropolymer (PTFE, FEP, ETFE) layers which act as the main barrier. Because samples used in GC work can be volatile at room temperatures, it is important to choose the right GC septa for your application. Choosing the wrong septa could lead to compromised test results.

Links:

• Natural PTFE-Red PTFE Application Note