| abstract |
Method and apparatus for picking up liquid sample material, such as blood serum, in a sample pick-up probe and for ejecting the sample from the probe into a reagent chemically reactive with the sample for analysis. Before ejecting the sample from the probe, the probe is inserted into the reagent for a period of time sufficient for the reagent to consume any residue of sample adherent to the exterior of the probe. Thereafter, the sample to be analyzed is ejected from the probe into the reagent and the resulting sample-reagent reaction is measured. Isolation between the sample within the probe and the reagent may be maintained while the probe is in the reagent by a bubble of air drawn into a tip end of the probe before inserting the probe into the reagent. Since the sample residue adherent to the probe is removed before ejecting the sample material for analysis, the residue is eliminated as a source of analysis error and, in addition, is eliminated as a source of carryover contamination of the next sample to be picked up by the probe. |