Sulfur hexafluoride and perfluoropropane do not escape from a plastic syringe closed with a stopcock.

Abstract

To evaluate during various intervals of time the escape of long-acting gases contained in a plastic syringe closed with a stopcock or a plastic cap. A 60-ml plastic syringe was filled or partially filled with a long-acting gas, either sulfur hexafluoride or perfluoropropane. The tip of the syringe was closed with either a stopcock or the syringe's plastic cap. After various intervals of time, the concentration of the long-acting gas in the syringe was measured by gas chromatography. The concentration of both long-acting gases was higher than 98% at 24 hours after filling when the syringe was closed with a stopcock; however, it was less than 41% when the syringe was filled and capped tightly with its plastic cap. The proportion of long-acting gases escaping in 24 hours from a filled syringe capped with a stopcock is clinically insignificant.