Method for evacuating and then collecting medium samples in containers sealed by a resilient stopper at substantially atmospheric pressure

A method for the evacuation of containers having a resilient stopper sealing the interior of the container at substantially atmospheric pressure well prior to the collection of the sample, and the collection of medium samples therein, which comprises, at or shortly before the time of collection of the sample, piercing the stopper by a first cannula connected at one end to a pressure-reducing device, thereby forming an opening through the stopper occupied by the cannula, and connecting the interior of the container with the pressure-reducing device via the first cannula;

• evacuating the container to a desired subatmospheric pressure;
• withdrawing the first cannula from the interior of the test tube sufficiently to permit the stopper opening to close after such withdrawal;
• penetrating the stopper by a second cannula connected at one end to a medium source, thereby connecting the source with the interior of the container via the second cannula;
• and then sucking medium into the container under the influence of the subatmospheric pressure effected by means of the pressure reduction.