Method and apparatus for aspirating and dispensing small liquid samples in an automated clinical analyzer

1. A method for providing a desired volume of a first liquid within a biochemical analyzer, the method comprising the steps of:

aspirating a slug of the first liquid from a first container into a probe, the slug comprising an excess portion and a desired portion of the first liquid,

ejecting a portion of the excess portion of the first liquid from the probe into a drain;

and then:

dispensing the desired volume of first liquid into a second container, wherein the second container has a second liquid therein: and

wherein dispensing the desired volume of first liquid into a second container comprises:

positioning the probe near the bottom of the second container:

dispensing the desired volume of first liquid:

raising the probe towards the top of the second container still within the mixture of first and second liquids; and,

aspirating a small volume of the mixture of first and second liquids into the probe.

2. The method of claim 1 wherein a portion of the first liquid remains in the probe after dispensing.

3. The method of claim 1 further comprising mixing the mixture of first and second liquids within the second container by lowering the probe into the second container and rapidly moving the probe in a mixing pattern.

4. The method of claim 1 wherein the first liquid is a liquid sample taken from a patient's infections, bodily fluids or abscesses and wherein the second liquid is a chemical reagent.

5. The method of claim 1 wherein the desired volume of the first liquid is in the range of 1-3 microliters.

6. The method of claim 3 wherein rapidly moving the probe in a mixing pattern comprises rapidly and repeatedly moving the probe in a generally parabolic or generally “boomerang-shaped” ellipsoidal mixing pattern within the liquid mixture.