Patent ID: 8052929

Claim:
A method of mixing substances within a receptacle having a plurality of interconnected chambers, the method comprising the steps of: (a) orienting the receptacle in an analyzer so that gravity can draw the contents of a first chamber of the receptacle into a second chamber of the receptacle when fluid communication is established between the first and second chambers; (b) establishing fluid communication between the first and second chambers; (c) applying a compressive force to the contents of the second chamber so that the contents of the second chamber are moved into the first chamber; (d) removing the compressive force of step (c) so that gravity draws the contents of the first chamber into the second chamber without applying a compressive force to the first chamber, (e) repeating steps (c) and (d) one or more times; and (f) detecting with an optical detector positioned adjacent to the first camber an optical signal emitted by the contents of the first chamber.