In instrumental analysis, sample bottles, which are also known as vials, threaded sample bottles, fine-thread bottles, flared rim bottles, rolled rim bottles, snap cap bottles, snap ring neck bottles or injection bottles, are fitted with closures, which usually consist of a perforated cap with an inserted septum seal. Usually, septum seals consist of an elastomer such as natural rubber, butyl rubber, silicone rubber or fluororubber.
For better chemical resistance, seals are laminated with thin films of fluoropolymers, generally on product side. Depending on the application, elastomers can also be laminated with thin films made of metal or another polymer such as homopolymers, copolymers, polymer blends.
For sampling, the septum is punctured with the cannula of a microlitre syringe, an aliquot of the gaseous or liquid samples is taken and injected automatically or manually into the analyzer.