Headspace sampling system

摘要

Methods and apparatus for collecting gasses from the sample headspace of a sealed sample container are disclosed. The gasses in the sample headspace are withdrawn by inserting a probe into the sample headspace and permitting the gasses to flow into an external headspace. The probe is then disconnected from the sample to seal the external headspace and the external headspace is then connected to an analytical instrument such as a gas chromatograph to permit the sample gasses to be transferred out of the external headspace and into the instrument. The step of transferring the gasses is preferably accomplished by connecting a source of carrier gas to an inlet port of the external headspace and sweeping the sample gasses from the external headspace. In certain preferred embodiments of the present invention, vibration is used to promote the formation of sample gasses either by vibrating the sample container itself or by moving the sample container relative to a stop to vibrate a septum which seals the sample container in certain embodiments. In these embodiments, the agitation created by such vibrations increases the rate of outgassing from the sample to the sample headspace. Also, in certain embodiments, the external headspace includes a flexible portion that is vibrated to agitate the external headspace and thereby promote uniform dispersion of sample gasses throughout the headspace.