Methods and apparatus to agitate a liquid

1. A cartridge comprising:

a carrier having a base and a collar extending from the base; and

a container having a top and a bottom, the bottom of the container selectively rotatable relative to the base, the container movable away from the base from a first position in which the bottom of the container is non-rotatably coupled to the base to a second position in which the bottom of the container is rotatable relative to the base, the bottom of the container including a post extending into the collar, the post rotatable in the collar when the container is in the second position.

2. The cartridge of claim 1 , wherein the carrier includes a ridge extending from the base.

3. The cartridge of claim 2 , wherein the ridge forms a ring, and the collar is within the ring.

4. The cartridge of claim 2 , wherein, in the first position, the ridge is engaged with the bottom of the container to non-rotatably couple the bottom of the container to the base, and in the second position, the ridge is disengaged from the bottom of the container and the bottom of the container is rotatable about the collar.

5. The cartridge of claim 4 , wherein the ridge extends from the base a first distance and the collar extends from the base a second distance greater than the first distance.

6. The cartridge of claim 5 , wherein, in the second position, the container is moved away from the base a third distance that is between the first distance and the second distance.

7. The cartridge of claim 1 , wherein the top of the container includes a throat having a first opening to receive a pipette to access a liquid in the container.

8. The cartridge of claim 7 , wherein the carrier includes a cover that has a second opening, the throat extending at least partially into the second opening.

9. The cartridge of claim 8 , wherein the throat is slidable in the second opening when the container is moved between the first position and the second position.

10. The cartridge of claim 8 , wherein the throat is rotatable in the second opening when the container is in the second position.

11. The cartridge of claim 1 , wherein the container holds a liquid reagent with paramagnetic particles, the liquid reagent to be used in a diagnostic analysis.

12. A cartridge comprising:

a carrier including:

a base;

a ridge extending from the base; and

a collar extending from the base; and

a container in the carrier, the container selectively slidable in the carrier from a first position in which the container is non-rotatably coupled to the carrier to a second position in which the container is rotatably coupled to the carrier.

13. The cartridge of claim 12 , wherein, in the first position, the ridge engages the container to non-rotatably couple the container to the base, and in the second position, the container is disengaged from the ridge and the container is rotatable about the collar.

14. The cartridge of claim 13 , wherein the container includes:

a bottom; and

a rim extending from the bottom of the container, the ridge to engage the rim when the container is in the first position to prevent rotation of the container relative to the base.

15. A cartridge comprising:

a carrier having a base and a collar extending from the base; and

a container supported by the base, the container movable away from the base from a first position in which the container is non-rotatably coupled to the base to a second position in which the container is rotatably coupled to the base, the base having an opening extending between a first side and a second side of the base, the opening extending through the collar, the opening to enable a shaft to be inserted through the opening to engage the container to move the container between the first position and the second position.

16. The cartridge of claim 15 , wherein the container includes a post extending from the container, the post extending at least partially into the collar.

17. The cartridge of claim 16 , wherein the post includes a notch to receive a protrusion on the shaft.

18. The cartridge of claim 12 , wherein the container has a top wall and a cylindrical throat extending from the top wall, and wherein the container has a first opening extending through the cylindrical throat and the top wall.

19. The cartridge of claim 18 , wherein the carrier includes a cover over the container, the cover having a second opening, the cylindrical throat extending at least partially into the second opening in the cover.

20. The cartridge of claim 19 , further including a cap at least partially disposed in the second opening and coupled to the throat.