Automated assay machine and assay tray

A method of performing an automated immunoassay using a machine having a moveable table and a tray having a plurality of assay wells therein where each well contains an immunosorbent bead having an antibody or antigen bound thereto and maintains the immunoabsorbent bead out of alignment with an optical analysis path, the machine further having a plurality of rows of dispensing tubes mounted on a platform which may be moved so as to move said dispensing tubes into and out of said wells, each row of said dispensing tubes being coupled through a peristaltic dispensing pump to a separate reservoir for storing various liquids, and having a row of aspirating tubes mounted adjacent to one row of said dispensing tubes close enough that said dispensing tubes and said aspirating tubes may both be lowered into the same row of wells, said row of aspirating tubes being coupled to an aspiration pump and waste receptacle and mounted on a separately moving platform which enables the aspirating tubes to be lowered into and raised out of said wells, and having a heating element under said table and a shroud over said table above said heating element comprising the steps of:

• (1) filling the reservoirs for four rows of dispensing tubes with, respectively, buffer, enzyme-labelled antibody reagent, substrate and enzyme deactivator appropriate for the automated assay being performed where the buffer is loaded into the reservoir coupled to the row of dispensing tubes mounted adjacent to said row of aspirating tubes;
• (2) loading each of the assay wells with sample liquid from a donor and with control reagent;
• (3) moving the table to register one row of wells below the row of dispensing tubes coupled to the buffer solution reservoir and pumping buffer into the wells so registered;
• (4) repeating step (3) for all the other sample containing rows of wells;
• (5) moving the table over the heating element and under said shroud and controlling the heating element so as to control the temperature of the liquid in said wells for an appropriate incubation time;
• (6) moving the table so that each row of sample containing wells is, in turn, registered under said row of aspirating tubes and lowering said aspirating tubes and the adjacent row of dispensing tubes into each row of wells so registered and activating the aspiration pump to pump out liquid from each said well and activating said dispensing pump to pump said buffer into said row of wells and repeating this aspirating and dispensing of buffer cycle a sufficient number of times to wash each said bead and each said well in each said row of wells;
• (7) registering each row of wells below the row of dispensing tubes coupled to said reservoir containing enzyme labelled antibody and pumping same into each well;
• (8) moving said table to place said tray over said heating element and under said shroud and controlling said heating element to incubate the contents of the wells;
• (9) registering each row of wells under said row of aspirating tubes and lowering said aspirating tubes into each row of wells in turn and aspirating out the liquid in each said well;
• (10) washing each said well using the procedure of step (6) above;
• (11) registering each row of wells in turn beneath the row of dispensing tubes coupled to the reservoir containing substrate and pumping substrate into each well;
• (12) moving the table to place the tray under said shroud and over said heating element and controlling said heating element to incubate the contents of said wells;
• (13) registering each row of wells under the row of dispensing tubes coupled to the reservoir containing enzyme deactivator and pumping same into each well;
• and
• (14) maintaining said bead out of alignment with said optical path and passing a beam of light through the liquid in each well along said optical path and reading the amount of light transmission through said liquid.

An apparatus for automatically performing immunoassays using a spectrophotometer comprising:

• a spectrophotometer means for projecting a beam of light and for measuring the light intensity in said beam of light at a position removed from the position of the source of said beam of light;
• a tray having a plurality of assay wells arranged in rows, each well for containing liquids needed in said assay and a solid phase having immobilized thereon a specific immunoglobulin for the antigen/hapten of interest or an antigen for which the antibody of interest is specific;
• means in each assay well for preventing said solid phase from ever residing in a place in said well which would block the path of said light beam used to measure the results of said assay;
• a head assembly translatable along a vertical axis;
• at least one liquid aspirating manifold mounted on said head assembly having an outlet and a plurality of spaced inlets each fitted with a plurality of vertically depending liquid aspirating tubes arranged in a row with spacing to match the spacing of the rows of said assay wells;
• means mounting said liquid aspirating manifold to said head assembly for moving said liquid aspirating manifold vertically even when said head assembly is not moving;
• sump means in each said well for providing a location from which all the liquid in each said well may be removed by an aspirating tube at any time without interference between said solid phase and said aspirating tube;
• a plurality of liquid dispensing manifolds mounted on said head assembly and having a plurality of inlets, each adapted to be connected to a source of a different liquid to be used in said assay, each said liquid dispensing manifold having a plurality of spaced outlets each fitted with a vertically depending liquid dispensing tube, the spacing between said dispensing tubes being in correspondence with the spacing between said wells of said assay tray;
• a plurality of dispensing pump means each coupling one of said liquid sources to one of said liquid dispensing manifolds for pumping liquids from said source out the corresponding ones of said dispensing tubes;
• an aspirating pump means coupling said aspirating manifold to waste for pumping liquids from the sump regions of any assay wells that said aspirating tubes are in;
• means for moving said head assembly along its vertical axis;
• a table mounted beneath said head assembly and adapted to carry said tray, said table being movable horizontally relative to said head assembly;
• means for moving said table horizontally so as to position any said row of said wells in registry with any said row of dispensing tubes or with said row of aspirating tubes;
• incubation means located adjacent to said table for controlling the temperature of fluid in said wells;
• means for controlling each of said moving means for said head assembly and said table, said dispensing pump means, said aspirating pump means, said spectrophotometer means and said incubation means such that predetermined volumes of predetermined liquids are added to and removed from said wells in a predetermined sequence and such that the liquids in said wells are subjected to incubation times at controlled temperatures for intervals at predetermined times in said sequence and for causing said table to move said table such that each well is moved into the path of a light beam from said spectrophotometer at a predetermined time in said sequence such that said light beam passes through the liquid in said well without being blocked by said solid phase and the light absorption by said liquid is measured.