Diagnostic analyzers with pretreatment carousels and related methods

An apparatus comprising:

• a first carousel comprising:
• a first annular array of slots to receive a first reaction vessel;
• a first track of rotation about the first carousel having a first diameter;
• and
• a second track of rotation about the first carousel having a second diameter smaller than the first diameter;
• a first diverter to move the first reaction vessel from the first track to the second track;
• a second carousel coaxial with the first carousel, the second carousel comprising a second annular array of slots to receive a second reaction vessel;
• a vessel loader to load the first reaction vessel into one of the first annular array of slots and to load the second reaction vessel into one of the second annular array of slots;
• a sample container having a liquid sample;
• a first pipetting mechanism;
• and
• a computer processor including software programmed to control the first pipetting mechanism to aspirate an amount of the liquid sample from the sample container and dispense the amount of the liquid sample into the second reaction vessel on the second carousel.