The present invention relates to an automated apparatus for retrieving liquid samples such as pretreated blood serum from a multiplicity of sample tubes or vials so that the withdrawn samples can subsequently be tested and analyzed.
There are presently a large number of routine clinical tests, such as blood tests in which fluid samples, e.g. blood samples are placed in a test tube or vial. The samples are appropriately treated, for example to separate the serum from the red blood cells, additives for the tests are added to sample, and thereafter the actual tests are performed, either in the vial or by withdrawing the sample from the vial and testing it outside thereof.
One such test which has recently been developed forms the subject matter of the commonly owned, co-pending U.S. patent application bearing Ser. No. 875,475, filed Feb. 6, 1978 for SOLID PHASE IMMUNAL FLUORESCENT ASSAY METHOD, now U.S. Pat. No. 4,201,763. In that patent application, there is described a fluorescence immunoassay (FIA) for antigens (or haptens) and their antibodies through the use of an immune reactant related to the antibody or antigen to be determined which is covalently bonded or coupled to polymeric particles whose size permits direct measurement of a labeled immunological reagent's fluorescence in an aqueous suspension thereof by direct optical spectroscopy.
Typically, the particles, unknown immune reactant, and appropriate fluorescently labeled immune reactant are mixed under conditions so that a quantity of the labeled immune reactant proportional to the concentration of the unknown immune reactant is immunologically bound, directly or indirectly, to the particles. The particles are then physically separated, usually by centrifuging them, typically at 1500 g to pack the particles at the bottom of the test tube into a pellet. The supernatant is decanted, to the extent necessary the tube or vial is blotted dry and a barbital buffer is added to the pellet in the test tube to reconstitute it and resuspend the particles to form a suspension which includes the fluorescent particles.
The suspension is then analyzed on a fluorometer to determine the concentration of fluorescent particles in the sample to obtain information from which unknown antigen or antibody can be determined.
As has been customery in the past, these tests have heretofore been performed manually one after the other. This required, inter alia, a vigorous manual shaking of the test tube to reconstitute each pellet and resuspend the fluorescent particles. To obtain an accurate test it is, of course, necessary that the suspension be uniform which prolonged the time during which the tube had to be shaken. Thereafter, the sample was fluorometrically analyzed, either in the test tube or by pouring it from the tube into a suitable container of a fluorometer.
This procedure is time-consuming and requires the constant close supervision by a highly skilled technician. More importantly, it gives no assurance that an adequate mixing of the sample has taken place. Without such mixing, however, the ultimate readout is inaccurate and can render the entire test of questionable value. Further, the test is relatively expensive because of the close and constant supervision it requires.