Abstract: Rotaxanes and pseudorotaxanes, methods of making them, intermediates in their formation and methods of using them in sensors are provided based upon changes in color absorption upon cation contact.

Abstract: A carrier tube system and method for using the same includes a carrier tube that is configured to receive a capillary blood tube, and a cap which seals the carrier tube to isolate the blood in the capillary tube from the surrounding atmosphere. The carrier tube system can be placed in a centrifuge which separates the blood with its component parts and optically reads the resulting layer thicknesses. The cap of the carrier tube can include a gear portion which is adapted for engagement with an indexing mechanism of the centrifuge, so that the indexing mechanism can rotate the carrier tube system about its longitudinal axis during centrifugation, thus allowing the optical reader of the centrifuge to take layer thickness readings at various positions about the circumference of the capillary tube.