FRAMINGHAM (10/23/2003) - TTP LabTech's comPOUND Double-Density (D2) sample store can hold up to twice the number of samples, 200,000 tubes, as the original same footprint. The new system stores two shorter microtubes (0.35ml) instead of one standard 1.0ml microtube in each carousel hole. When a tube is requested, the system actually retrieves both tubes from the one carousel hole using compressed air rather than robotic arms. While the unwanted tube is clamped in the airlock valve, the requested tube is free to be delivered. The tube that is not required is then moved back to its storage location. This process happens within the unit's self-contained environment (as cold as -20°C, under nitrogen), so the nonselected tube is never exposed to the outside environment, the company says. It takes an average of five seconds for the 1ml tubes and eight seconds for the 0.35ml tubes to be delivered.