A method of processing a sample in a receptacle comprising a plurality of chambers. Each of the chambers is connected to at least one other chamber by a portal and at least a first one of the chambers is formed of a flexible material. The method includes the steps of causing gas bubbles contained in the first chamber to accumulate in a portion of the first chamber, applying a compressive external force to the first chamber to cause some or all of the liquid contents of the first chamber to flow into an interconnected second chamber through a portal connecting the first and second chambers; and preventing the gas bubbles accumulated in a portion of the first chamber from flowing through the portal into the second chamber.