U.S. patent number RE30,627 [Application Number 05/784,648] was granted by the patent office on 1981-05-26 for apparatus for performing chemical and biological analysis.
This patent grant is currently assigned to Picker Corporation. Invention is credited to Kenneth D. Bagshawe, James E. Kemble.
United States Patent |
RE30,627 |
Bagshawe , et al. |
May 26, 1981 |
**Please see images for:
( Certificate of Correction ) ** |
Apparatus for performing chemical and biological analysis
Abstract
A system for the automated analysis of large numbers of liquid
samples, in which a multiplicity of sample tubes are loaded in
racks into a cassette and the loaded cassette is transferred from
station to station, with operations of sample insertion, dilution,
reagent addition and withdrawal for filtering being performed at
successive stations. At each station there is a separate processing
module adapted to receive the cassette, each module including the
apparatus necessary for performing one of the abovementioned
operations on each individual sample tube when it is located at a
particular operational location in the cassette. Each module also
has members for shifting the racks in the cassette in such manner
that all tubes pass through the operational location in turn while
strictly maintaining the same order of sequence throughout the
operations.
Inventors: |
Bagshawe; Kenneth D. (London,
GB2), Kemble; James E. (Burgess Hill,
GB2) |
Assignee: |
Picker Corporation (Cleveland,
OH)
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Family
ID: |
10441575 |
Appl.
No.: |
05/784,648 |
Filed: |
April 4, 1977 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
404720 |
Oct 9, 1973 |
03923463 |
Dec 2, 1975 |
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Foreign Application Priority Data
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Oct 9, 1972 [GB] |
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46521/72 |
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Current U.S.
Class: |
436/48; 210/387;
422/561; 422/63; 422/66; 422/71; 436/44; 436/57; 436/808 |
Current CPC
Class: |
G01N
35/026 (20130101); Y10T 436/110833 (20150115); Y10T
436/114165 (20150115) |
Current International
Class: |
G01N
33/483 (20060101); G01N 35/02 (20060101); G01N
031/00 (); G01N 033/56 () |
Field of
Search: |
;23/253R,259,23R,253TP,23B,230.3,920 ;250/328
;210/238,344,346,486,387 ;422/63,65,66,69,71,81,101 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Turk; Arnold
Attorney, Agent or Firm: Scrivener, Clarke, Scrivener and
Johnson
Claims
We claim:
1. Apparatus for analysing a plurality of liquid samples, each
sample being in a tube, and comprising a cassette having a shell in
which a plurality of such tubes are to be contained in sequence,
said cassette having apertures in its walls through which means,
operated by apparatus external to the cassette, actuate and advance
the tubes sequentially and stepwise past a fixed point, said
cassette being freely removable from the operating apparatus,
without disturbing the contained tubes, to other locations, the
initial sequence of tubes being maintained throughout.
2. Apparatus according to claim 1, wherein the cassette is provided
with a lid which occludes the open ends of all the tubes contained
in the cassette.
3. Apparatus according to claim 1, wherein the cassette carries
racks of moulded plastics in which the tubes are an integral part
of the rack.
4. Apparatus according to claim 1 wherein said tubes are arrayed in
linear series in substantially rigid racks to be received within
the cassette shell, and said actuating means advances the racks
with the tubes therein sequentially past said fixed point.
5. In combination with the apparatus of claim 1, liquid analysis
apparatus comprising at least one module with means to carry out a
physical operation on the liquid samples and with a location to
receive a selected one of said cassettes at a time and means to
actuate operative elements which advance the tubes inside said
cassette sequentially past a fixed point.
6. Liquid analysis apparatus according to claim 5 wherein
operations of dispensing, transferring and diluting liquid samples
are performed by means of pumps actuated by signals received from a
control unit which incorporates an electronic data register,
according to a sequence of instructions supplied to the control
unit by a human operator in at least one prior operation and which
instructions may be varied according to the requirements of
analytical protocol.
7. Apparatus according to claim 5, wherein liquid transfer and
dispensing operations are performed by pumps with fixed stroke
volume, multiples of this fixed volume being transferred by
repetitive action of such pumps depending on signals from a control
unit with a data register operating on prior instructions.
8. Liquid analysis apparatus according to claim 5, comprising means
to transfer radioactive components from a multiplicity of reactions
occurring in said tubes simultaneously to a corresponding
multiplicity of filters on a continuous tape, photomultiplier
devices to convert the radioactivity at a multiplicity of filter
sites into signals which are accumulated and counted directly in
electronic data registers, the accumulated totals associated with
prior instructions being stored at other locations in the register,
and means to perform calculations and to transfer the accumulated
totals and results of the calculations to appropriate output
terminals.
9. In combination with apparatus according to claim 8, a tape of
strong flexible plastics material, bearing at appropriate intervals
a series of locations where the tape is perforated and where the
perforations are surmounted by filter discs adherent to the tape at
the margins of the filter discs, said tape additionally having
holes or indentations to aid in the .[.correction.]. .Iadd.correct
.Iaddend.registration of the tape at operational locations. .Iadd.
10. Analysis apparatus for performing at least two operations on a
liquid sample in a sample container comprising first and second
support means at respective first and second stations, each support
means being adapted to removably receive a cassette having therein
a plurality of sample containers, means at substantially fixed
points on said respective support means for performing respective
first and second operations on the liquid samples in the respective
containers, drive means carried by the respective support means and
arranged to project into a cassette when on said support means and
engage the containers therein for moving the same in a closed path
sequentially from an initial relationship to one another past an
operation performing means at the fixed points on the respective
support means and back to the initial relationship, and means for
operating the respective operation performing means upon arrival of
a container at each of the respective fixed points. .Iaddend.
.Iadd. 11. Apparatus as claimed in claim 10, wherein the first
operation performing means is adapted to dispense samples to be
analysed into the containers and the second operation performing
means is arranged to dispense a reaction medium into each
container. .Iaddend. .Iadd. 12. Apparatus as claimed in claim 10,
wherein the operation performing means each include at least one
pump, and control means are provided for controlling operation of
the said at least one pump independently for each station.
.Iaddend..Iadd. 13. Apparatus as claimed in claim 12, wherein the
pumps have fixed stroke volumes and multiples of the fixed stroke
volume of each pump are dispensed by repetitive action of the pump
in dependence on control signals from the control means. .Iaddend.
.Iadd. 14. Apparatus as claimed in claim 10 including a third
station at which a third operation is performed on said liquid
samples in said sample containers, the apparatus at said third
station including support means and drive means substantially
identical to said support means and said drive means at said first
and second stations. .Iaddend. .Iadd. 15. Apparatus as claimed in
claim 14, wherein the first operation performing means is adapted
to dispense samples to be analysed into the containers, the second
operation performing means is adapted to dispense a reaction medium
into the containers and the third operation performing means is
adapted to remove liquid from each container. .Iaddend..Iadd. 16.
Apparatus as claimed in claim 15, wherein the third station
includes means for filtering the liquid removed from each
container. .Iaddend..Iadd. 17. The apparatus of claim 16 wherein
the filtering means comprises a flexible tape bearing at intervals
a series of locations where at each interval (1) the tape is
perforated and where at each interval (2) a filter defined by
porous membrane filter material surmounts the perforations and is
adherent to the tape at the margins of the filter. .Iaddend..Iadd.
18. A filtration tape for use in radioimmunoassay studies or the
like comprising:
(a) an elongate carrier tape;
(b) the tape having a plurality of longitudinally spaced filtration
locations;
(c) each such location including:
(i) a set of perforations each of which perforations extends
through the tape, and
(ii) a filter disc overlying each set of perforations and secured
to the tape at the margin of the filter disc. .Iaddend..Iadd. 19. A
tape as claimed in claim 18, including registration means on the
carrier tape. .Iaddend..Iadd. 20. A tape as claimed in claim 18,
wherein the carrier tape has holes or indentations to aid in
correct registration of the tape. .Iadd. 21. A tape as claimed in
claim 18, wherein each filter disc is made of glass fibre.
.Iaddend..Iadd. 22. A tape as claimed in claim 18, wherein each
filter disc is made of cellulose acetate. .Iadd. 23. A tape as
claimed in claim 18, wherein the carrier tape is made of polyvinyl
chloride. .Iaddend..Iadd. 24. Portable apparatus for receiving a
plurality of linear arrays of sample containers and for permitting
circulatory movement of the arrays within the apparatus, the
apparatus comprising a rectangular cassette having a base wall and
two pairs of opposed side walls defining a space for receiving the
arrays, the space within the cassette being divided into two
compartments by dividing wall means extending parallel to one pair
of opposed side walls and terminating short of each wall of the
other pair of side walls to leave a gap, each compartment being
adapted to receive a plurality of arrays supported on the base wall
and arranged side-by-side, each array extending perpendicular to
the dividing wall means and being movable in a direction parallel
to the dividing wall means through the respective compartment and
from one compartment through the respective gap between the
dividing wall means and the respective wall of the other pair of
side walls, retaining and guide means for preventing withdrawal of
arrays when in the compartments from the compartments and for
guiding arrays in their movement through each compartment, and
aperture means provided in at least some of the walls for providing
access to arrays when in the cassette for means for moving the
arrays through the compartments and from one compartment to the
other compartment. .Iaddend..Iadd. 25. Apparatus as claimed in
claim 24, including a lid for closing the open end of containers
when in the cassette. .Iaddend..Iadd. 26. Apparatus as claimed in
claim 24, wherein the retaining and guide means are provided along
the one pair of opposed side walls and correspondingly on the
dividing wall means. .Iaddend..Iadd. 27. Apparatus as claimed in
claim 24, wherein the retaining and guide means include a lip
extending inwardly of the respective compartment on each of the
walls of the one pair of side walls and on the dividing wall means.
.Iaddend..Iadd. 28. Apparatus as claimed in claim 24, wherein the
aperture means are provided in the one pair of opposed side walls.
.Iaddend..Iadd. 29. In combination with the apparatus as claimed in
claim 24, other apparatus for performing at least one operation of
dispensing, transferring and diluting a liquid sample, the other
apparatus comprising means for performing the operation, means
defining a location for receiving the cassette, and means for
moving the arrays when in the cassette along a predetermined path
past the operation performing means. .Iaddend..Iadd. 30. Apparatus
as claimed in claim 24, including a plurality of arrays received in
the compartments of the cassette, each array being provided with a
recess at each end for engagement with the retaining and guide
means. .Iaddend..Iadd. 31. Apparatus as claimed in claim 30,
wherein the arrays are formed of plastics material. .Iaddend.
.Iadd. 32. Apparatus as claimed in claim 30, wherein the arrays
define a linear array of receptacles each for receiving a sample
container. .Iaddend..Iadd. 33. Apparatus as claimed in claim 30,
wherein the arrays provide a linear array of sample containers
formed integrally therewith. .Iaddend..Iadd. 34. A cassette for use
in apparatus for analysing a plurality of liquid samples, each
sample being in a container, said cassette comprising wall means
defining a space for receiving a plurality of such containers, said
wall means having aperture means therethrough having through which
means, operated by apparatus external to the cassette, will in use
actuate and advance the containers sequentially and stepwise past a
fixed point, said cassette being adapted to be freely removable
from the operating apparatus, without disturbing the containers
when contained therein, to other locations, the initial sequence of
such containers being maintained throughout. .Iaddend. .Iadd. 35. A
cassette according to claim 34, including a lid for occluding the
open ends of containers when contained in the cassette.
.Iaddend..Iadd. 36. Apparatus comprising a cassette according to
claim 34 and arrays of moulded plastic racks to be received within
the cassette, the containers being an integral part of the racks.
.Iaddend..Iadd. 37. Apparatus comprising a cassette according to
claim 34 and containers for containing liquid samples, said
containers being arranged in linear series in substantially rigid
racks to be received in the cassette. .Iaddend..Iadd. 38. In
combination a cassette according to claim 34 and liquid analysis
apparatus comprising at least one module including: means for
carrying out a physical operation on a liquid sample, a location to
receive said cassette, and means for advancing containers when in
said cassette sequentially past a fixed point. .Iaddend. .Iadd. 39.
A method of dispensing a plurality of samples to be analysed and of
mixing each sample with a reaction medium, the method comprising,
at a first station dispensing a plurality of samples to be analysed
into a plurality of containers as they are moved sequentially past
a sample dispensing head in a closed path, moving the liquid
samples in the containers as a group to a second station, at the
second station moving the samples in the containers in the order in
which they were dispensed past a reaction medium dispensing head in
a closed path, dispensing the reaction medium into the containers,
and removing the liquid samples and reaction medium in the
containers as a group from the second station. .Iaddend..Iadd. 40.
A method as claimed in claim 39, including removing the samples and
reaction medium from the containers, wherein the samples and
reaction medium in the containers are moved as a group from the
second station to a third station and, at the third station the
containers containing the samples and reaction medium are moved
past a removing head in the order in which they were dispensed and
in a closed path. .Iaddend..Iadd. 41. A method as claimed in claim
40, wherein the containers are moved between the stations manually.
.Iaddend..Iadd. 42. A method as claimed in claim 40, wherein,
between the second and the third stations, the containers are
placed as a group in an incubator. .Iaddend..Iadd. 43. A method of
mixing a plurality of samples to be analysed with a reaction medium
and withdrawing the mixture, the method comprising placing
containers containing the samples in a first station, at the first
station moving the samples in the containers sequentially past a
reaction medium dispensing head, dispensing reaction medium into
the containers, moving the containers as a group from the first
station and placing them in a second station, at the second station
moving the sample containers sequentially past a sample withdrawing
head in the same order as that in which the sample containers moved
through the first station, and withdrawing the samples and reaction
medium from the containers. .Iaddend..Iadd. 44. A method as claimed
in claim 43, wherein the sample mixtures withdrawn from the
containers in the second station are filtered and the components
retained by the filter means are analysed. .Iaddend. .Iadd. 45. A
method as claimed in claim 44, wherein the reaction medium is
radioactive and the radioactivity of the filter means is
determined. .Iaddend. .Iadd. 46. Analysis apparatus for performing
at least one operation on a liquid sample in a sample container
said apparatus comprising support means for removably receiving a
cassette having therein a plurality of sample containers, means for
performing the operation disposed at a substantially fixed point on
said support means, drive means carried by said support means and
arranged to project into a cassette on said support means and
engage the containers therein for moving the same in a closed path
sequentially from an initial relationship to one another past the
operation performing means at said fixed point and back to the
initial relationship, and means for operating said operation
performing means upon arrival of a container at said fixed point.
.Iaddend..Iadd. 47. Apparatus as claimed in claim 46 wherein the
support means comprises a base module, said base module being one
of a plurality of substantially similar base modules, each being
adapted to removably receive a cassette transferred thereto from
another of said base modules. .Iaddend. .Iadd. 48. A method of
performing at least two operations on a liquid sample in each of a
plurality of liquid sample containers, the method comprising
arranging the sample containers in a predetermined sequence in a
portable cassette, removably positioning the cassette at a first
station adjacent means for performing a first operation, moving the
liquid sample containers in a closed path in the cassette
sequentially past the first operation performing means, performing
the first operation on the containers, moving the cassette with the
liquid sample containers as a group therein from the first station
and positioning them in a second station adjacent means for
performing a second operation, moving the liquid sample containers
in a closed path in the cassette sequentially past the second
operation performing means, performing the second operation on the
containers, and moving the cassette with the liquid sample
containers as a group therein from the second station. .Iaddend.
.Iadd. 49. Filtration means for use in radioimmunoassay studies or
the like comprising:
(a) a strong flexible tape bearing at intervals a series of
locations where at each interval:
(i) the tape is perforated; and where at each interval
(ii) a filter disc defined by porous membrane filter material
surmounts the perforations and is adherent to the tape at the
margins of the filter disc. .Iaddend. .Iadd. 50. Filtration means
as claimed in claim 49, including registration means on the carrier
tape. .Iaddend..Iadd. 51. Filtration means as claimed in claim 49,
wherein the carrier tape has holes or indentations to aid in
correct registration of the tape. .Iaddend..Iadd. 52. Filtration
means as claimed in claim 49, wherein each filter disc is made of
glass fibre. .Iaddend..Iadd. 53. Filtration means as claimed in
claim 49, wherein each filter disc is made of cellulose acetate.
.Iaddend..Iadd. 54. Filtration means as claimed in claim 49,
wherein the carrier tape is made of polyvinyl chloride. .Iaddend.
Description
This invention relates to a system of analysis and automated
apparatus for the techniques of competitive protein binding
including radioimmuno assay and radiometric assay. These techniques
are widely used to measure the concentration in liquids of
substances hereinafter described as "the ligand" which bind to
specific antibodies or other macromolecules hereinafter described
as "specific antibody".
Ligand of the species to be measured, labelled with a radioisotope,
is added to a reaction tube containing a quantity of the unknown
sample liquid, before or after the addition of specific antibody.
The labelled ligand and the ligand in the unknown sample compete
for binding to the specific antibody. In similar tubes, in each
assay, known concentrations of unlabelled ligand are included to
provide reference standards. The amount of ligand is determined by
separating .[.antibody bound.]. .Iadd.antibody-bound
.Iaddend.ligand from free ligand by centrifugation or filtration
and by counting the amount of labelled ligand in the precipitate or
liquid phase.
To perform such reactions accurately, it is necessary to dispense
the sample and reagents accurately, to ensure complete mixing of
reagents and diluents, to incubate all samples and reference
standards for the same time at the same temperature and to separate
.[.antibody bound.]. .Iadd.antibody-bound .Iaddend.ligand from free
ligand efficiently. It is necessary to present reaction tubes in
orderly sequence at one or more locations for these operations, to
carry these tubes from one location to another, to maintain their
initial sequence and to occlude the open end of the tubes to
prevent spillage and evaporation. Competitive protein binding
assays have been described for several hundred substances and a
laboratory may need to use many different assay protocols and to
assay batches of very variable size.
Existing apparatus provides arrangements for dispensing samples and
reagents into tubes located in carrier racks. Such racks readily
get out of sequence and sample identification by manual methods is
tedious and inconvenient. Means for diluting samples by constant
ratios also exist but existing automatic devices do not allow for
variation of ratio from sample to sample, nor do they readily
perform serial dilutions as required for reference standards. The
rate limiting stage in competitive protein binding assays is
generally that of isotope counting which is performed
conventionally by nucleonic counters with automatic sample
changers. The use of computers has hitherto been limited to
performing calculations on data output by nucleonic counters and
this entails feeding in sample identification data in addition to
the preparation of the initial work sheet.
A hitherto known system provides the means for individually
adjusted dilution ratios and for serial dilutions in dilution
containers and analysis performed in conveyor belts of incubation
pots. This system, however, is an integrated operation which allows
no interruption between sample input and data output so that
variation of assay protocol, incubation time and counting time is
severely restricted and this limits the rate of throughput of
samples and applicability of the system.
According to the present invention, there is provided apparatus for
analysing a plurality of liquid samples, each sample being in a
container or tube, such that a linear series of such tubes forms a
rigid or semi-rigid rack, and comprising a cassette within the
shell of which a plurality of such racks are to be contained said
cassette having apertures in its walls, through which means,
operated by apparatus external to the cassette, actuate and advance
the racks and tubes sequentially and stepwise past a fixed point
and such that a cassette be freely removable from the operating
apparatus without disturbing or removing the contained racks and
tubes so as to be transportable to other locations, the initial
sequence of tubes and racks being maintained throughout.
The present invention facilitates the analysis of samples in small
or large batches, permits wide choice of volume and dilution ratio
for each sample, choice of volume and sequence of addition of
reagents and choice of assay protocol. Further, it minimises the
time required for documentation and provides a high rate of sample
throughput.
The equipment may include two teleprinters and six modules, five of
which are, for convenience, arranged together to form the sample
processing unit whilst the sixth module is described as the control
unit.
As already specified, multiple tubes are located in a multiplicity
of racks which in turn are located within a cassette. The cassettes
can be transferred manually between different modules. These
features permit all the tubes for one assay to be kept together,
the initial sequence of tubes to be rigidly maintained and the
simultaneous processing of different assays employing wide
variation in analytical protocol.
Another novel feature in the preferred embodiment of the invention
is the control unit which is programmed to control the operations
of the modules. This unit also counts simultaneously the
radioactivity from a multiplicity of reactions and is programmed to
compute the results of assays from these counts and to present the
data in any desired form at the appropriate terminal. This feature
greatly increases the throughput of the assay system whilst
reducing the number of controls on the processing units. It further
avoids the use of a plurality of nucleonic radioactivity counters
such as ratemeters or scalers, reduces the opportunity for human
error and minimises documentation.
An apparatus and system according to the invention will now be
described in some detail by way of example and with reference to
the accompanying drawings, in which:
FIG. 1 is a block diagram of the overall system.
FIG. 2 is a pictorial diagram showing detail of a sample processing
unit of the system of FIG. 1,
FIG. 3 is a detail of filter tape employed in the system, and
FIG. 4 is a diagrammatic pictorial view of a cassette holding
reaction tubes.
Referring firstly to FIG. 1, the control unit 1 incorporates a
small on-line computer 2 with electronic data registers 3 and
interface unit 4, radioactivity counting locations 9 defined
between two rows of photomultiplier units 5 arranged in pairs and
connected to corresponding discriminator units 6 that feed signals
to the interface, and means for advancing tape 7 bearing
radioactive locations from a supply spool 8 to the counting
locations 9 and thence to a take up spool 10.
The control unit is programmed by three classes of data. Class I
data pertain to the instruction and operational language of the
computer unit and identification of storage locations in its data
register and these are normally stored permanently within the data
register. Class II data pertain to the analytical procedure and
protocol for a specific assay and are normally input at the
beginning of any assay operation. Class III data pertain to
individual samples within an assay and are input by the operator
during the first stage of each assay.
Data are input via any suitable terminal but a teleprinter 51 with
paper tape punch and reader is the preferred form. Data are stored
in two ways. Data controlling functions, such as dispensing,
transferring and dilution by the sample processing unit 52, are
retained in the electronic data register 3 of the control unit 1.
These data, together with all other data relating to an assay, are
stored as a punched tape which is prepared during the course of the
sample input. The paper tape is retained for use at a later stage
in the analysis. In addition, all Class II and III data are typed
out by the input teleprinter 51 using a simple conversational
language to provide the work record. No further records or data
input are required of the operator. The remaining functions of the
control unit will be described after the cassette and sample
processing modules.
Referring now to .[.FIG..]. .Iadd.FIGS. 3 and .Iaddend.4, showing a
cassette 14 containing reaction tubes for samples to be processed,
part of the technique to be described is based on a principle of
moving .Iadd.linear arrays of sample containers comprising
.Iaddend.racks 11, holding tubes 12 at uniform pitch, stepwise past
a fixed operation point 34. The racks are of uniform length and are
arrayed within the shell or cassette 14 in two .[.bands.].
.Iadd.banks .Iaddend.11A, 11B. Each bank consists of a plurality of
racks 11 placed side by side along their long sides. The racks in
the two banks are more or less end to end but are so staggered that
the front rack of one bank and the rear rack of the other bank are
free to move endwise .Iadd.into spaces 11C and 11D at the opposite
ends of the respective banks 11A and 11B (FIG. 2) .Iaddend.and thus
be moved from one bank to the other. Such a movement is carried out
stepwise by levers and pushrods .Iadd.13 .Iaddend. in .[.the.].
.Iadd.a cassette support means at a first station comprising
.Iaddend.base module 15 (FIG. 2) which .Iadd.removably
.Iaddend.receives the cassette 14 and these .Iadd.levers and
pushrods 13.Iaddend., operating through apertures 16 in the walls
of the cassette, move each rack in turn past the operation location
34. On completion of the endwise displacement of .Iadd.the
.Iaddend.two .Iadd.end .Iaddend.racks, each bank of racks 11A, 11B
is displaced as a whole at right angles to the stepwise movement by
an amount equal to the thickness of a rack so that the original
staggered disposition of the banks is regained and the next racks
in the sequence are aligned for endwise movement.
At the end of a sequence of operations, the racks can be advanced
by the levers and pushrods .Iadd.13 .Iaddend.to the original
starting position, the first reaction tube of the first rack in any
cassette being identified by a suitable marker; in the preferred
form, a magnet location in the rack beneath the first tube provides
a signal to a fixed sensor located in the base module. Outward
displacement of the banks of racks is prevented by side walls 17
and the two banks are separated by a shallow central partition 18
.Iadd.terminating short of the end walls 17a to leave the gaps for
the endwise displacement of the two end racks into the spaces 11C,
11D as above explained.Iaddend.. Lips 19 on the racks engage under
corresponding lips 19A on the side walls and central partition to
prevent upward displacement of the racks. The levers and pushrods
which move the racks are linked mechanically to switches in the
module base which thus sense the position of the racks. In this
way, the precise sequence and location of tubes and racks is
maintained and made known to the control unit during operational
procedures.
In order to transfer the reaction tubes 12 to another base module,
it is simply necessary to lift the cassette 14 from one module
.Iadd.at a second or further stations .Iaddend.and engage it in the
corresponding location of another. Various sizes of reaction tube
can be accommodated within a rack. Disposable moulded plastics
racks with integral containers may be used or racks may consist of
a "permanent" shoe and a "disposable" multitube component. In one
typical cassette arrangement, a total of 420 reaction tubes of 3 ml
volume are accommodated with 15 tubes in each of 28 racks.
When it is necessary to seal the tubes, the cassette 14 is placed
in a closed box or a lid 21 is fitted to occlude the open ends of
all the tubes 12. The lid may consist of a flexible sheet which is
pulled taut over the tubes but in the preferred form, a layer of
foam rubber 22 is sandwiched between a rigid top sheet 23 and a
smooth plastic under lining 24. In this way, effective occlusion of
all the tubes can be obtained at a single action and the manual
sealing and unsealing of many tubes by individual stoppers is
obviated.
The sample processing unit (FIG. 2), consists of (1) sample
insertion module 25, (2) dilution module 26, (3) reagent addition
module 27, (4) transfer module 28 and (5) filtration module 29.
The insertion module 25 has the following features. A location in
the base module 15 for the reaction tube cassette 14, which
location provides the means to move the levers and pushrods and
switches which advance the tubes in the cassette to and from the
operational location. It incorporates a probe unit 30, pump 31 and
wash facilities 32 for the transfer of liquid samples 33 to the
reaction tube 12 at the operational location 34 without carry-over
of solution from one sample to another. The probe 30 carried on a
suitable arm and connected by flexible plastic tubing to the pump
unit 31 descends into a sample tube 33 at the sample location. The
pump withdraws a quantity of the sample in excess of that required
for the reaction. The probe is then elevated and rotated through an
arc to a wash and wipe location 32 where the probe descends. In
this position, two claws faced by a tape 35 of absorbent paper
close on the probe. Drops of liquid left on the outside of the
probe are thus removed by the absorbent paper when the probe is
raised. After elevation of the probe, the claws open and the paper
is advanced. The probe then swings through a further arc to the
operational location 34 where it descends into the reaction tube
12, the pump discharges the required volume and the probe is lifted
and taken back to the wash location where the probe is washed
internally and externally by the action if another pump supplying
wash fluid and again the probe is wiped on the outside before
returning to the sample input location.
The volume of sample dispensed into each reaction tube 12 is
determined by the analytical protocol. The same volume may be
dispensed into all tubes or varied according to the requirements
for dilution. In the preferred form, the pump takes up or
discharges a unit volume at each stroke and the control unit
controls the number of strokes in each take up and dispensing
operation according to assay protocol.
Operation of the sample insertion module 25 is effected by the
operator ensuring the Class I and Class II data have been input to
the control unit and Class III data pertaining to each sample are
typed on the input teleprinter with the sample tube 23 in the
sample location. Typing in the command signal, initiates the
insertion module sequence.
When a complete batch of reference standards and samples have been
dispensed, the racks 11 are returned to their initial sequence and
the cassette 14 is transferred manually to the dilution module 26,
as indicated by the arrows 20.
The dilution module 26 similarly provides a location for the
cassette and means for advancing reaction tubes past the
operational location. In order to perform dilutions, one or more
pumps add precise amounts of diluent to the sample and other pump
or pumps remove similar amounts through a multi-channel probe. Thus
a series of dilution steps may be performed. Between each step, the
sample and diluent are mixed by the operation of an additional pump
with a reciprocating action operating a plunger in one channel of
the probe. The volume dispensed or taken up by each pump action may
be adjustable over a wide range but, in the preferred form, one or
more fixed volumes are dispensed or taken up at each stroke and
repetitive strokes are used to give any multiple of these fixed
volumes. The operation of the dispensing and takeup pumps is
controlled by the control unit 1 according to Class II and III
data. Once the dilution sequence has been initiated, no further
intervention is required by the operator.
On completion of dilution and return of the reaction tubes 12 to
the start position, the cassette 14 is transferred to a
corresponding location on the reagent dispensing module 27. As the
reaction tubes step to the operational location, one or more
reagents are dispensed in the precisely required volume by probe
and pump unit of this module. Pump operations may be controlled by
settings on the module itself or by programming the control unit.
On completion of dispensing and mixing, the occlusive lid 21 is
applied to the batch of tubes and the cassette incubated at the
desired temperature for the period required. The reagent dispensing
module 27 also incorporates a peristaltic pump so that when
required a suspension of charcoal or precipitating agent can be
dispensed from an agitated solution into the reaction tubes.
On completion of incubation, the cassette 14 is placed on the
transfer module 28 from whence the contents of the reaction tubes
12 are transferred to filter locations .[.36.]. on the filtration
module 29, the action of the two modules being closely integrated.
This transfer is effected in the preferred form from five reaction
tubes at a time but any convenient number may be used. Five probes
descend into five adjacent tubes. The probes are connected by
flexible tubes to five corresponding hemispherical domes .Iadd.37
.Iaddend.rigidly mounted on the .[.filtration unit 37.].
.Iadd.module 29.Iaddend.. Each probe contains a second channel
through which wash solution is pumped from a supply bottle.
.[.Filtration is performed at the locations 36 through a cellulose
acetate, or glass fibre membranes, or filters of similar porosity,
mounted at intervals over perforated segments of a flexible plastic
carrier tape 7, and sealed to the tape around the margins of the
filters..]. .Iadd.Filtration is performed through a filter material
which may be cellulose acetate, a glass fibre membrane or filter of
similar porosity mounted at intervals 36 on the tape 7 of strong
flexible material, such as polyvinyl chloride, which bears at said
intervals a series of locations 43 where the tape is perforated and
where the perforations are surmounted by the filter material 44
adherent to the tape at the margins of the filter material.
.Iaddend.The carrier tape is further marked at fixed intervals by
holes 41 (FIG. 3) or indentations so that its .[.position.].
.Iadd.registration at operational locations .Iaddend.may be
precisely controlled by sensors fixed to the filtration module
signalling to the control unit. The plastic tape 7 is supplied from
a spool 38 and fed through a series of locations to a take up
spool, the tape advancing stepwise by five locations at a time. At
the first five locations 39 on the filtration module 29, the
membranes are wetted with a protein solution. At the second five
locations, the five hemispherical domes are sealed against the
upper margin of each filter .[.disc 36.]. .Iadd.location
.Iaddend.by the elevation of a pressure plate 40 which bears on the
lower surface of the filter tape 7. This plate also has five
suction areas the peripheries of which seal on the under surfaces
of the margins of the filter locations 36 and a cavity within the
pressure plate communicates with a vacuum source. Elevation of the
pressure plate and activation of the vacuum source causes a
negative pressure to be transmitted across the filter
.[.membrane.]. and for the contents of the reaction tubes 12 to be
drawn through the flexible tubing to the filters where the
precipitates are retained on the filters. Wash solution is pumped
into the reaction tubes and this is also drawn through the filters.
Wash solution is also pumped to a series of outlets peripherally
disposed at each filter location so as to provide uniform washing
over the whole area of the filter .[.membrane.].. In the preferred
form, the filtrate proceeds to waste but counting of filtrate
radioactivity is an alternative to counting precipitate
radioactivity. On completion of filtration and washing, the
pressure plate 40 is lowered and the probe assembly on the transfer
module 28 elevated. Both tape 7 and reaction tubes 12 then advance
five locations. At the next station 42 the filter tape 7 is dried
by a fan heater and on emerging from this station, transparent
adhesive tape is applied to the filter bearing surface of the
carrier tape. After completion of one or more batches of samples,
the tape is rewound to its initial sequence and is then transferred
to the supply spool position 8 in the radioactivity detector
station.
Thus, in the manner just described, radioactive components from a
multiplicity of reactions occurring in said tubes are
simultaneously transferred to a corresponding multiplicity of
filters on the continuous tape. FIG. 1 shows a radioactivity
detector station at which photo multiplier devices 5 convert the
radioactivity at the multiplicity of filter sites into signals
which are accumulated and counted directly in electronic data
registers 1. The accumulated totals associated with prior
instructions are stored at other locations in the register assembly
1, and computer means 2 performs calculations and transfers the
accumulated totals and results of the calculations to appropriate
output terminal means denoted at 54.
At the radioactivity detector station, the tape 7 is transported by
pinch rollers 53 with drive mechanisms and is thus fed through five
counting locations 9. Movement of the carrier type is controlled as
on the filtration unit and the counting time is determined by the
assay protocol. At each of the five counting locations, there is an
opposed pair of photomultiplier tubes 5, the output from which
passes via a discriminator 6 and distribution unit to the
electronic data register 3 for counting.
Since the counting efficiency of photomultiplier tubes is variable,
a tape bearing radioactive filter locations is first advanced one
step at a time through the five count locations 9. The relative
efficiency of each pair of tubes 5 is thus determined and a
correction factor is then applied automatically to the counts
received from each location.
When the carrier tape 7 for an assay batch is placed in the
detector station of the control unit, the corresponding paper tape
is fed into the tape reader on an output teleprinter 54. As
radioactivity counting proceeds, the totals for each counting
location are associated with the corresponding data on the punch
tape. The reference standard line is then computed according to the
programme and the concentrations of ligand in the samples are
determined and statistical analyses are performed according to
standard analytical procedure. The assay data are output to the
teleprinter or alternative terminal.
* * * * *